From bc52ffb6aff200bcac05052adbe6b57be5e7d81c Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Tue, 23 Nov 2021 22:42:11 +0100
Subject: [PATCH 1/2] Reduce code output for reading maps

---
 integration/batching-with-context/batching.ts |  20 +-
 integration/batching/batching.ts              |  20 +-
 integration/simple-long/simple.ts             |  60 +++---
 integration/simple-optionals/simple.ts        |  80 ++++----
 integration/simple-snake/simple.ts            |  80 ++++----
 .../simple-unrecognized-enum/simple.ts        |  80 ++++----
 integration/simple/simple.ts                  | 180 +++++++-----------
 integration/struct/google/protobuf/struct.ts  |  20 +-
 .../use-date-string/use-date-string.ts        |  20 +-
 integration/use-date-true/use-date-true.ts    |  20 +-
 integration/value/google/protobuf/struct.ts   |  20 +-
 src/main.ts                                   |   8 +-
 12 files changed, 242 insertions(+), 366 deletions(-)

diff --git a/integration/batching-with-context/batching.ts b/integration/batching-with-context/batching.ts
index 30968e1ec..d89de0bd7 100644
--- a/integration/batching-with-context/batching.ts
+++ b/integration/batching-with-context/batching.ts
@@ -237,11 +237,9 @@ export const BatchMapQueryResponse = {
   fromJSON(object: any): BatchMapQueryResponse {
     const message = { ...baseBatchMapQueryResponse } as BatchMapQueryResponse;
     message.entities = {};
-    if (object.entities !== undefined && object.entities !== null) {
-      Object.entries(object.entities).forEach(([key, value]) => {
-        message.entities[key] = Entity.fromJSON(value);
-      });
-    }
+    Object.entries(object.entities ?? {}).forEach(([key, value]) => {
+      message.entities[key] = Entity.fromJSON(value);
+    });
     return message;
   },
 
@@ -259,13 +257,11 @@ export const BatchMapQueryResponse = {
   fromPartial(object: DeepPartial<BatchMapQueryResponse>): BatchMapQueryResponse {
     const message = { ...baseBatchMapQueryResponse } as BatchMapQueryResponse;
     message.entities = {};
-    if (object.entities !== undefined && object.entities !== null) {
-      Object.entries(object.entities).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.entities[key] = Entity.fromPartial(value);
-        }
-      });
-    }
+    Object.entries(object.entities ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.entities[key] = Entity.fromPartial(value);
+      }
+    });
     return message;
   },
 };
diff --git a/integration/batching/batching.ts b/integration/batching/batching.ts
index 9eef7d4c8..27297410b 100644
--- a/integration/batching/batching.ts
+++ b/integration/batching/batching.ts
@@ -235,11 +235,9 @@ export const BatchMapQueryResponse = {
   fromJSON(object: any): BatchMapQueryResponse {
     const message = { ...baseBatchMapQueryResponse } as BatchMapQueryResponse;
     message.entities = {};
-    if (object.entities !== undefined && object.entities !== null) {
-      Object.entries(object.entities).forEach(([key, value]) => {
-        message.entities[key] = Entity.fromJSON(value);
-      });
-    }
+    Object.entries(object.entities ?? {}).forEach(([key, value]) => {
+      message.entities[key] = Entity.fromJSON(value);
+    });
     return message;
   },
 
@@ -257,13 +255,11 @@ export const BatchMapQueryResponse = {
   fromPartial(object: DeepPartial<BatchMapQueryResponse>): BatchMapQueryResponse {
     const message = { ...baseBatchMapQueryResponse } as BatchMapQueryResponse;
     message.entities = {};
-    if (object.entities !== undefined && object.entities !== null) {
-      Object.entries(object.entities).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.entities[key] = Entity.fromPartial(value);
-        }
-      });
-    }
+    Object.entries(object.entities ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.entities[key] = Entity.fromPartial(value);
+      }
+    });
     return message;
   },
 };
diff --git a/integration/simple-long/simple.ts b/integration/simple-long/simple.ts
index 55dfae0da..dd511df17 100644
--- a/integration/simple-long/simple.ts
+++ b/integration/simple-long/simple.ts
@@ -212,23 +212,17 @@ export const SimpleWithMap = {
   fromJSON(object: any): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
     message.nameLookup = {};
-    if (object.nameLookup !== undefined && object.nameLookup !== null) {
-      Object.entries(object.nameLookup).forEach(([key, value]) => {
-        message.nameLookup[key] = String(value);
-      });
-    }
+    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
+      message.nameLookup[key] = String(value);
+    });
     message.intLookup = {};
-    if (object.intLookup !== undefined && object.intLookup !== null) {
-      Object.entries(object.intLookup).forEach(([key, value]) => {
-        message.intLookup[Number(key)] = Number(value);
-      });
-    }
+    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
+      message.intLookup[Number(key)] = Number(value);
+    });
     message.longLookup = {};
-    if (object.longLookup !== undefined && object.longLookup !== null) {
-      Object.entries(object.longLookup).forEach(([key, value]) => {
-        message.longLookup[key] = Long.fromString(value as string);
-      });
-    }
+    Object.entries(object.longLookup ?? {}).forEach(([key, value]) => {
+      message.longLookup[key] = Long.fromString(value as string);
+    });
     return message;
   },
 
@@ -258,29 +252,23 @@ export const SimpleWithMap = {
   fromPartial(object: DeepPartial<SimpleWithMap>): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
     message.nameLookup = {};
-    if (object.nameLookup !== undefined && object.nameLookup !== null) {
-      Object.entries(object.nameLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.nameLookup[key] = String(value);
-        }
-      });
-    }
+    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.nameLookup[key] = String(value);
+      }
+    });
     message.intLookup = {};
-    if (object.intLookup !== undefined && object.intLookup !== null) {
-      Object.entries(object.intLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.intLookup[Number(key)] = Number(value);
-        }
-      });
-    }
+    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.intLookup[Number(key)] = Number(value);
+      }
+    });
     message.longLookup = {};
-    if (object.longLookup !== undefined && object.longLookup !== null) {
-      Object.entries(object.longLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.longLookup[key] = Long.fromValue(value);
-        }
-      });
-    }
+    Object.entries(object.longLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.longLookup[key] = Long.fromValue(value);
+      }
+    });
     return message;
   },
 };
diff --git a/integration/simple-optionals/simple.ts b/integration/simple-optionals/simple.ts
index f3b9af737..5b205c05b 100644
--- a/integration/simple-optionals/simple.ts
+++ b/integration/simple-optionals/simple.ts
@@ -893,23 +893,17 @@ export const SimpleWithMap = {
   fromJSON(object: any): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        message.entitiesById[Number(key)] = Entity.fromJSON(value);
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      message.entitiesById[Number(key)] = Entity.fromJSON(value);
+    });
     message.nameLookup = {};
-    if (object.nameLookup !== undefined && object.nameLookup !== null) {
-      Object.entries(object.nameLookup).forEach(([key, value]) => {
-        message.nameLookup[key] = String(value);
-      });
-    }
+    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
+      message.nameLookup[key] = String(value);
+    });
     message.intLookup = {};
-    if (object.intLookup !== undefined && object.intLookup !== null) {
-      Object.entries(object.intLookup).forEach(([key, value]) => {
-        message.intLookup[Number(key)] = Number(value);
-      });
-    }
+    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
+      message.intLookup[Number(key)] = Number(value);
+    });
     return message;
   },
 
@@ -939,29 +933,23 @@ export const SimpleWithMap = {
   fromPartial(object: DeepPartial<SimpleWithMap>): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.entitiesById[Number(key)] = Entity.fromPartial(value);
-        }
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.entitiesById[Number(key)] = Entity.fromPartial(value);
+      }
+    });
     message.nameLookup = {};
-    if (object.nameLookup !== undefined && object.nameLookup !== null) {
-      Object.entries(object.nameLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.nameLookup[key] = String(value);
-        }
-      });
-    }
+    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.nameLookup[key] = String(value);
+      }
+    });
     message.intLookup = {};
-    if (object.intLookup !== undefined && object.intLookup !== null) {
-      Object.entries(object.intLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.intLookup[Number(key)] = Number(value);
-        }
-      });
-    }
+    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.intLookup[Number(key)] = Number(value);
+      }
+    });
     return message;
   },
 };
@@ -1169,11 +1157,9 @@ export const SimpleWithSnakeCaseMap = {
   fromJSON(object: any): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        message.entitiesById[Number(key)] = Entity.fromJSON(value);
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      message.entitiesById[Number(key)] = Entity.fromJSON(value);
+    });
     return message;
   },
 
@@ -1191,13 +1177,11 @@ export const SimpleWithSnakeCaseMap = {
   fromPartial(object: DeepPartial<SimpleWithSnakeCaseMap>): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.entitiesById[Number(key)] = Entity.fromPartial(value);
-        }
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.entitiesById[Number(key)] = Entity.fromPartial(value);
+      }
+    });
     return message;
   },
 };
diff --git a/integration/simple-snake/simple.ts b/integration/simple-snake/simple.ts
index 0dea90a41..c51d4c1f3 100644
--- a/integration/simple-snake/simple.ts
+++ b/integration/simple-snake/simple.ts
@@ -893,23 +893,17 @@ export const SimpleWithMap = {
   fromJSON(object: any): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        message.entitiesById[Number(key)] = Entity.fromJSON(value);
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      message.entitiesById[Number(key)] = Entity.fromJSON(value);
+    });
     message.nameLookup = {};
-    if (object.nameLookup !== undefined && object.nameLookup !== null) {
-      Object.entries(object.nameLookup).forEach(([key, value]) => {
-        message.nameLookup[key] = String(value);
-      });
-    }
+    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
+      message.nameLookup[key] = String(value);
+    });
     message.intLookup = {};
-    if (object.intLookup !== undefined && object.intLookup !== null) {
-      Object.entries(object.intLookup).forEach(([key, value]) => {
-        message.intLookup[Number(key)] = Number(value);
-      });
-    }
+    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
+      message.intLookup[Number(key)] = Number(value);
+    });
     return message;
   },
 
@@ -939,29 +933,23 @@ export const SimpleWithMap = {
   fromPartial(object: DeepPartial<SimpleWithMap>): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.entitiesById[Number(key)] = Entity.fromPartial(value);
-        }
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.entitiesById[Number(key)] = Entity.fromPartial(value);
+      }
+    });
     message.nameLookup = {};
-    if (object.nameLookup !== undefined && object.nameLookup !== null) {
-      Object.entries(object.nameLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.nameLookup[key] = String(value);
-        }
-      });
-    }
+    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.nameLookup[key] = String(value);
+      }
+    });
     message.intLookup = {};
-    if (object.intLookup !== undefined && object.intLookup !== null) {
-      Object.entries(object.intLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.intLookup[Number(key)] = Number(value);
-        }
-      });
-    }
+    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.intLookup[Number(key)] = Number(value);
+      }
+    });
     return message;
   },
 };
@@ -1169,11 +1157,9 @@ export const SimpleWithSnakeCaseMap = {
   fromJSON(object: any): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
     message.entities_by_id = {};
-    if (object.entities_by_id !== undefined && object.entities_by_id !== null) {
-      Object.entries(object.entities_by_id).forEach(([key, value]) => {
-        message.entities_by_id[Number(key)] = Entity.fromJSON(value);
-      });
-    }
+    Object.entries(object.entities_by_id ?? {}).forEach(([key, value]) => {
+      message.entities_by_id[Number(key)] = Entity.fromJSON(value);
+    });
     return message;
   },
 
@@ -1191,13 +1177,11 @@ export const SimpleWithSnakeCaseMap = {
   fromPartial(object: DeepPartial<SimpleWithSnakeCaseMap>): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
     message.entities_by_id = {};
-    if (object.entities_by_id !== undefined && object.entities_by_id !== null) {
-      Object.entries(object.entities_by_id).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.entities_by_id[Number(key)] = Entity.fromPartial(value);
-        }
-      });
-    }
+    Object.entries(object.entities_by_id ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.entities_by_id[Number(key)] = Entity.fromPartial(value);
+      }
+    });
     return message;
   },
 };
diff --git a/integration/simple-unrecognized-enum/simple.ts b/integration/simple-unrecognized-enum/simple.ts
index 2de1a45ef..9634d65e4 100644
--- a/integration/simple-unrecognized-enum/simple.ts
+++ b/integration/simple-unrecognized-enum/simple.ts
@@ -884,23 +884,17 @@ export const SimpleWithMap = {
   fromJSON(object: any): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        message.entitiesById[Number(key)] = Entity.fromJSON(value);
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      message.entitiesById[Number(key)] = Entity.fromJSON(value);
+    });
     message.nameLookup = {};
-    if (object.nameLookup !== undefined && object.nameLookup !== null) {
-      Object.entries(object.nameLookup).forEach(([key, value]) => {
-        message.nameLookup[key] = String(value);
-      });
-    }
+    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
+      message.nameLookup[key] = String(value);
+    });
     message.intLookup = {};
-    if (object.intLookup !== undefined && object.intLookup !== null) {
-      Object.entries(object.intLookup).forEach(([key, value]) => {
-        message.intLookup[Number(key)] = Number(value);
-      });
-    }
+    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
+      message.intLookup[Number(key)] = Number(value);
+    });
     return message;
   },
 
@@ -930,29 +924,23 @@ export const SimpleWithMap = {
   fromPartial(object: DeepPartial<SimpleWithMap>): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.entitiesById[Number(key)] = Entity.fromPartial(value);
-        }
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.entitiesById[Number(key)] = Entity.fromPartial(value);
+      }
+    });
     message.nameLookup = {};
-    if (object.nameLookup !== undefined && object.nameLookup !== null) {
-      Object.entries(object.nameLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.nameLookup[key] = String(value);
-        }
-      });
-    }
+    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.nameLookup[key] = String(value);
+      }
+    });
     message.intLookup = {};
-    if (object.intLookup !== undefined && object.intLookup !== null) {
-      Object.entries(object.intLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.intLookup[Number(key)] = Number(value);
-        }
-      });
-    }
+    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.intLookup[Number(key)] = Number(value);
+      }
+    });
     return message;
   },
 };
@@ -1160,11 +1148,9 @@ export const SimpleWithSnakeCaseMap = {
   fromJSON(object: any): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        message.entitiesById[Number(key)] = Entity.fromJSON(value);
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      message.entitiesById[Number(key)] = Entity.fromJSON(value);
+    });
     return message;
   },
 
@@ -1182,13 +1168,11 @@ export const SimpleWithSnakeCaseMap = {
   fromPartial(object: DeepPartial<SimpleWithSnakeCaseMap>): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.entitiesById[Number(key)] = Entity.fromPartial(value);
-        }
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.entitiesById[Number(key)] = Entity.fromPartial(value);
+      }
+    });
     return message;
   },
 };
diff --git a/integration/simple/simple.ts b/integration/simple/simple.ts
index f2329834f..83eff8844 100644
--- a/integration/simple/simple.ts
+++ b/integration/simple/simple.ts
@@ -1036,47 +1036,33 @@ export const SimpleWithMap = {
   fromJSON(object: any): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        message.entitiesById[Number(key)] = Entity.fromJSON(value);
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      message.entitiesById[Number(key)] = Entity.fromJSON(value);
+    });
     message.nameLookup = {};
-    if (object.nameLookup !== undefined && object.nameLookup !== null) {
-      Object.entries(object.nameLookup).forEach(([key, value]) => {
-        message.nameLookup[key] = String(value);
-      });
-    }
+    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
+      message.nameLookup[key] = String(value);
+    });
     message.intLookup = {};
-    if (object.intLookup !== undefined && object.intLookup !== null) {
-      Object.entries(object.intLookup).forEach(([key, value]) => {
-        message.intLookup[Number(key)] = Number(value);
-      });
-    }
+    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
+      message.intLookup[Number(key)] = Number(value);
+    });
     message.mapOfTimestamps = {};
-    if (object.mapOfTimestamps !== undefined && object.mapOfTimestamps !== null) {
-      Object.entries(object.mapOfTimestamps).forEach(([key, value]) => {
-        message.mapOfTimestamps[key] = fromJsonTimestamp(value);
-      });
-    }
+    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
+      message.mapOfTimestamps[key] = fromJsonTimestamp(value);
+    });
     message.mapOfBytes = {};
-    if (object.mapOfBytes !== undefined && object.mapOfBytes !== null) {
-      Object.entries(object.mapOfBytes).forEach(([key, value]) => {
-        message.mapOfBytes[key] = bytesFromBase64(value as string);
-      });
-    }
+    Object.entries(object.mapOfBytes ?? {}).forEach(([key, value]) => {
+      message.mapOfBytes[key] = bytesFromBase64(value as string);
+    });
     message.mapOfStringValues = {};
-    if (object.mapOfStringValues !== undefined && object.mapOfStringValues !== null) {
-      Object.entries(object.mapOfStringValues).forEach(([key, value]) => {
-        message.mapOfStringValues[key] = value as string | undefined;
-      });
-    }
+    Object.entries(object.mapOfStringValues ?? {}).forEach(([key, value]) => {
+      message.mapOfStringValues[key] = value as string | undefined;
+    });
     message.longLookup = {};
-    if (object.longLookup !== undefined && object.longLookup !== null) {
-      Object.entries(object.longLookup).forEach(([key, value]) => {
-        message.longLookup[Number(key)] = Number(value);
-      });
-    }
+    Object.entries(object.longLookup ?? {}).forEach(([key, value]) => {
+      message.longLookup[Number(key)] = Number(value);
+    });
     return message;
   },
 
@@ -1130,61 +1116,47 @@ export const SimpleWithMap = {
   fromPartial(object: DeepPartial<SimpleWithMap>): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.entitiesById[Number(key)] = Entity.fromPartial(value);
-        }
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.entitiesById[Number(key)] = Entity.fromPartial(value);
+      }
+    });
     message.nameLookup = {};
-    if (object.nameLookup !== undefined && object.nameLookup !== null) {
-      Object.entries(object.nameLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.nameLookup[key] = String(value);
-        }
-      });
-    }
+    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.nameLookup[key] = String(value);
+      }
+    });
     message.intLookup = {};
-    if (object.intLookup !== undefined && object.intLookup !== null) {
-      Object.entries(object.intLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.intLookup[Number(key)] = Number(value);
-        }
-      });
-    }
+    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.intLookup[Number(key)] = Number(value);
+      }
+    });
     message.mapOfTimestamps = {};
-    if (object.mapOfTimestamps !== undefined && object.mapOfTimestamps !== null) {
-      Object.entries(object.mapOfTimestamps).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.mapOfTimestamps[key] = value;
-        }
-      });
-    }
+    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.mapOfTimestamps[key] = value;
+      }
+    });
     message.mapOfBytes = {};
-    if (object.mapOfBytes !== undefined && object.mapOfBytes !== null) {
-      Object.entries(object.mapOfBytes).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.mapOfBytes[key] = value;
-        }
-      });
-    }
+    Object.entries(object.mapOfBytes ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.mapOfBytes[key] = value;
+      }
+    });
     message.mapOfStringValues = {};
-    if (object.mapOfStringValues !== undefined && object.mapOfStringValues !== null) {
-      Object.entries(object.mapOfStringValues).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.mapOfStringValues[key] = value;
-        }
-      });
-    }
+    Object.entries(object.mapOfStringValues ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.mapOfStringValues[key] = value;
+      }
+    });
     message.longLookup = {};
-    if (object.longLookup !== undefined && object.longLookup !== null) {
-      Object.entries(object.longLookup).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.longLookup[Number(key)] = Number(value);
-        }
-      });
-    }
+    Object.entries(object.longLookup ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.longLookup[Number(key)] = Number(value);
+      }
+    });
     return message;
   },
 };
@@ -1619,11 +1591,9 @@ export const SimpleWithSnakeCaseMap = {
   fromJSON(object: any): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        message.entitiesById[Number(key)] = Entity.fromJSON(value);
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      message.entitiesById[Number(key)] = Entity.fromJSON(value);
+    });
     return message;
   },
 
@@ -1641,13 +1611,11 @@ export const SimpleWithSnakeCaseMap = {
   fromPartial(object: DeepPartial<SimpleWithSnakeCaseMap>): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
     message.entitiesById = {};
-    if (object.entitiesById !== undefined && object.entitiesById !== null) {
-      Object.entries(object.entitiesById).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.entitiesById[Number(key)] = Entity.fromPartial(value);
-        }
-      });
-    }
+    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.entitiesById[Number(key)] = Entity.fromPartial(value);
+      }
+    });
     return message;
   },
 };
@@ -1743,11 +1711,9 @@ export const SimpleWithMapOfEnums = {
   fromJSON(object: any): SimpleWithMapOfEnums {
     const message = { ...baseSimpleWithMapOfEnums } as SimpleWithMapOfEnums;
     message.enumsById = {};
-    if (object.enumsById !== undefined && object.enumsById !== null) {
-      Object.entries(object.enumsById).forEach(([key, value]) => {
-        message.enumsById[Number(key)] = value as number;
-      });
-    }
+    Object.entries(object.enumsById ?? {}).forEach(([key, value]) => {
+      message.enumsById[Number(key)] = value as number;
+    });
     return message;
   },
 
@@ -1765,13 +1731,11 @@ export const SimpleWithMapOfEnums = {
   fromPartial(object: DeepPartial<SimpleWithMapOfEnums>): SimpleWithMapOfEnums {
     const message = { ...baseSimpleWithMapOfEnums } as SimpleWithMapOfEnums;
     message.enumsById = {};
-    if (object.enumsById !== undefined && object.enumsById !== null) {
-      Object.entries(object.enumsById).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.enumsById[Number(key)] = value as number;
-        }
-      });
-    }
+    Object.entries(object.enumsById ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.enumsById[Number(key)] = value as number;
+      }
+    });
     return message;
   },
 };
diff --git a/integration/struct/google/protobuf/struct.ts b/integration/struct/google/protobuf/struct.ts
index d54b6ca9b..c7c383d41 100644
--- a/integration/struct/google/protobuf/struct.ts
+++ b/integration/struct/google/protobuf/struct.ts
@@ -127,11 +127,9 @@ export const Struct = {
   fromJSON(object: any): Struct {
     const message = { ...baseStruct } as Struct;
     message.fields = {};
-    if (object.fields !== undefined && object.fields !== null) {
-      Object.entries(object.fields).forEach(([key, value]) => {
-        message.fields[key] = value as any | undefined;
-      });
-    }
+    Object.entries(object.fields ?? {}).forEach(([key, value]) => {
+      message.fields[key] = value as any | undefined;
+    });
     return message;
   },
 
@@ -149,13 +147,11 @@ export const Struct = {
   fromPartial(object: DeepPartial<Struct>): Struct {
     const message = { ...baseStruct } as Struct;
     message.fields = {};
-    if (object.fields !== undefined && object.fields !== null) {
-      Object.entries(object.fields).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.fields[key] = value;
-        }
-      });
-    }
+    Object.entries(object.fields ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.fields[key] = value;
+      }
+    });
     return message;
   },
 };
diff --git a/integration/use-date-string/use-date-string.ts b/integration/use-date-string/use-date-string.ts
index 57bf66733..4fce84847 100644
--- a/integration/use-date-string/use-date-string.ts
+++ b/integration/use-date-string/use-date-string.ts
@@ -86,11 +86,9 @@ export const Todo = {
         ? String(object.optionalTimestamp)
         : undefined;
     message.mapOfTimestamps = {};
-    if (object.mapOfTimestamps !== undefined && object.mapOfTimestamps !== null) {
-      Object.entries(object.mapOfTimestamps).forEach(([key, value]) => {
-        message.mapOfTimestamps[key] = String(value);
-      });
-    }
+    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
+      message.mapOfTimestamps[key] = String(value);
+    });
     return message;
   },
 
@@ -120,13 +118,11 @@ export const Todo = {
     message.repeatedTimestamp = (object.repeatedTimestamp ?? []).map((e) => e);
     message.optionalTimestamp = object.optionalTimestamp ?? undefined;
     message.mapOfTimestamps = {};
-    if (object.mapOfTimestamps !== undefined && object.mapOfTimestamps !== null) {
-      Object.entries(object.mapOfTimestamps).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.mapOfTimestamps[key] = value;
-        }
-      });
-    }
+    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.mapOfTimestamps[key] = value;
+      }
+    });
     return message;
   },
 };
diff --git a/integration/use-date-true/use-date-true.ts b/integration/use-date-true/use-date-true.ts
index d820bf767..12a5fbd40 100644
--- a/integration/use-date-true/use-date-true.ts
+++ b/integration/use-date-true/use-date-true.ts
@@ -86,11 +86,9 @@ export const Todo = {
         ? fromJsonTimestamp(object.optionalTimestamp)
         : undefined;
     message.mapOfTimestamps = {};
-    if (object.mapOfTimestamps !== undefined && object.mapOfTimestamps !== null) {
-      Object.entries(object.mapOfTimestamps).forEach(([key, value]) => {
-        message.mapOfTimestamps[key] = fromJsonTimestamp(value);
-      });
-    }
+    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
+      message.mapOfTimestamps[key] = fromJsonTimestamp(value);
+    });
     return message;
   },
 
@@ -120,13 +118,11 @@ export const Todo = {
     message.repeatedTimestamp = (object.repeatedTimestamp ?? []).map((e) => e);
     message.optionalTimestamp = object.optionalTimestamp ?? undefined;
     message.mapOfTimestamps = {};
-    if (object.mapOfTimestamps !== undefined && object.mapOfTimestamps !== null) {
-      Object.entries(object.mapOfTimestamps).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.mapOfTimestamps[key] = value;
-        }
-      });
-    }
+    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.mapOfTimestamps[key] = value;
+      }
+    });
     return message;
   },
 };
diff --git a/integration/value/google/protobuf/struct.ts b/integration/value/google/protobuf/struct.ts
index d54b6ca9b..c7c383d41 100644
--- a/integration/value/google/protobuf/struct.ts
+++ b/integration/value/google/protobuf/struct.ts
@@ -127,11 +127,9 @@ export const Struct = {
   fromJSON(object: any): Struct {
     const message = { ...baseStruct } as Struct;
     message.fields = {};
-    if (object.fields !== undefined && object.fields !== null) {
-      Object.entries(object.fields).forEach(([key, value]) => {
-        message.fields[key] = value as any | undefined;
-      });
-    }
+    Object.entries(object.fields ?? {}).forEach(([key, value]) => {
+      message.fields[key] = value as any | undefined;
+    });
     return message;
   },
 
@@ -149,13 +147,11 @@ export const Struct = {
   fromPartial(object: DeepPartial<Struct>): Struct {
     const message = { ...baseStruct } as Struct;
     message.fields = {};
-    if (object.fields !== undefined && object.fields !== null) {
-      Object.entries(object.fields).forEach(([key, value]) => {
-        if (value !== undefined) {
-          message.fields[key] = value;
-        }
-      });
-    }
+    Object.entries(object.fields ?? {}).forEach(([key, value]) => {
+      if (value !== undefined) {
+        message.fields[key] = value;
+      }
+    });
     return message;
   },
 };
diff --git a/src/main.ts b/src/main.ts
index 3f2436aae..a3b7991b6 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1083,14 +1083,12 @@ function generateFromJson(ctx: Context, fullName: string, messageDesc: Descripto
     if (isRepeated(field)) {
       if (isMapType(ctx, messageDesc, field)) {
         chunks.push(code`message.${fieldName} = {};`);
-        chunks.push(code`if (object.${fieldName} !== undefined && object.${fieldName} !== null) {`);
         const i = maybeCastToNumber(ctx, messageDesc, field, 'key');
         chunks.push(code`
-          Object.entries(object.${fieldName}).forEach(([key, value]) => {
+          Object.entries(object.${fieldName} ?? {}).forEach(([key, value]) => {
             message.${fieldName}[${i}] = ${readSnippet('value')};
           });
         `);
-        chunks.push(code`}`);
       } else if (isAnyValueType(field)) {
         chunks.push(code`
           message.${fieldName} = Array.isArray(object?.${fieldName}) ? [...object.${fieldName}] : [];
@@ -1304,16 +1302,14 @@ function generateFromPartial(ctx: Context, fullName: string, messageDesc: Descri
     if (isRepeated(field)) {
       if (isMapType(ctx, messageDesc, field)) {
         chunks.push(code`message.${fieldName} = {};`);
-        chunks.push(code`if (object.${fieldName} !== undefined && object.${fieldName} !== null) {`);
         const i = maybeCastToNumber(ctx, messageDesc, field, 'key');
         chunks.push(code`
-          Object.entries(object.${fieldName}).forEach(([key, value]) => {
+          Object.entries(object.${fieldName} ?? {}).forEach(([key, value]) => {
             if (value !== undefined) {
               message.${fieldName}[${i}] = ${readSnippet('value')};
             }
           });
         `);
-        chunks.push(code`}`);
       } else {
         chunks.push(code`
           message.${fieldName} = (object.${fieldName} ?? []).map((e) => ${readSnippet('e')});

From 1cea5dd1b905fd434d7c01fc79585a4d65da4098 Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Tue, 23 Nov 2021 23:37:51 +0100
Subject: [PATCH 2/2] Create maps in a single assignment

---
 integration/batching-with-context/batching.ts |  16 +-
 integration/batching/batching.ts              |  16 +-
 integration/simple-long/simple.ts             |  78 +++---
 integration/simple-optionals/simple.ts        | 104 +++++---
 integration/simple-snake/simple.ts            | 104 +++++---
 .../simple-unrecognized-enum/simple.ts        | 104 +++++---
 integration/simple/simple.ts                  | 228 +++++++++++-------
 integration/struct/google/protobuf/struct.ts  |  26 +-
 .../use-date-string/use-date-string.ts        |  26 +-
 integration/use-date-true/use-date-true.ts    |  26 +-
 integration/value/google/protobuf/struct.ts   |  26 +-
 src/main.ts                                   |  18 +-
 12 files changed, 470 insertions(+), 302 deletions(-)

diff --git a/integration/batching-with-context/batching.ts b/integration/batching-with-context/batching.ts
index d89de0bd7..4da12298a 100644
--- a/integration/batching-with-context/batching.ts
+++ b/integration/batching-with-context/batching.ts
@@ -236,10 +236,10 @@ export const BatchMapQueryResponse = {
 
   fromJSON(object: any): BatchMapQueryResponse {
     const message = { ...baseBatchMapQueryResponse } as BatchMapQueryResponse;
-    message.entities = {};
-    Object.entries(object.entities ?? {}).forEach(([key, value]) => {
-      message.entities[key] = Entity.fromJSON(value);
-    });
+    message.entities = Object.entries(object.entities ?? {}).reduce<{ [key: string]: Entity }>((acc, [key, value]) => {
+      acc[key] = Entity.fromJSON(value);
+      return acc;
+    }, {});
     return message;
   },
 
@@ -256,12 +256,12 @@ export const BatchMapQueryResponse = {
 
   fromPartial(object: DeepPartial<BatchMapQueryResponse>): BatchMapQueryResponse {
     const message = { ...baseBatchMapQueryResponse } as BatchMapQueryResponse;
-    message.entities = {};
-    Object.entries(object.entities ?? {}).forEach(([key, value]) => {
+    message.entities = Object.entries(object.entities ?? {}).reduce<{ [key: string]: Entity }>((acc, [key, value]) => {
       if (value !== undefined) {
-        message.entities[key] = Entity.fromPartial(value);
+        acc[key] = Entity.fromPartial(value);
       }
-    });
+      return acc;
+    }, {});
     return message;
   },
 };
diff --git a/integration/batching/batching.ts b/integration/batching/batching.ts
index 27297410b..1aa547719 100644
--- a/integration/batching/batching.ts
+++ b/integration/batching/batching.ts
@@ -234,10 +234,10 @@ export const BatchMapQueryResponse = {
 
   fromJSON(object: any): BatchMapQueryResponse {
     const message = { ...baseBatchMapQueryResponse } as BatchMapQueryResponse;
-    message.entities = {};
-    Object.entries(object.entities ?? {}).forEach(([key, value]) => {
-      message.entities[key] = Entity.fromJSON(value);
-    });
+    message.entities = Object.entries(object.entities ?? {}).reduce<{ [key: string]: Entity }>((acc, [key, value]) => {
+      acc[key] = Entity.fromJSON(value);
+      return acc;
+    }, {});
     return message;
   },
 
@@ -254,12 +254,12 @@ export const BatchMapQueryResponse = {
 
   fromPartial(object: DeepPartial<BatchMapQueryResponse>): BatchMapQueryResponse {
     const message = { ...baseBatchMapQueryResponse } as BatchMapQueryResponse;
-    message.entities = {};
-    Object.entries(object.entities ?? {}).forEach(([key, value]) => {
+    message.entities = Object.entries(object.entities ?? {}).reduce<{ [key: string]: Entity }>((acc, [key, value]) => {
       if (value !== undefined) {
-        message.entities[key] = Entity.fromPartial(value);
+        acc[key] = Entity.fromPartial(value);
       }
-    });
+      return acc;
+    }, {});
     return message;
   },
 };
diff --git a/integration/simple-long/simple.ts b/integration/simple-long/simple.ts
index dd511df17..95c7eda7a 100644
--- a/integration/simple-long/simple.ts
+++ b/integration/simple-long/simple.ts
@@ -211,18 +211,27 @@ export const SimpleWithMap = {
 
   fromJSON(object: any): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
-    message.nameLookup = {};
-    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
-      message.nameLookup[key] = String(value);
-    });
-    message.intLookup = {};
-    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
-      message.intLookup[Number(key)] = Number(value);
-    });
-    message.longLookup = {};
-    Object.entries(object.longLookup ?? {}).forEach(([key, value]) => {
-      message.longLookup[key] = Long.fromString(value as string);
-    });
+    message.nameLookup = Object.entries(object.nameLookup ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        acc[key] = String(value);
+        return acc;
+      },
+      {}
+    );
+    message.intLookup = Object.entries(object.intLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Number(value);
+        return acc;
+      },
+      {}
+    );
+    message.longLookup = Object.entries(object.longLookup ?? {}).reduce<{ [key: string]: Long }>(
+      (acc, [key, value]) => {
+        acc[key] = Long.fromString(value as string);
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -251,24 +260,33 @@ export const SimpleWithMap = {
 
   fromPartial(object: DeepPartial<SimpleWithMap>): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
-    message.nameLookup = {};
-    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.nameLookup[key] = String(value);
-      }
-    });
-    message.intLookup = {};
-    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.intLookup[Number(key)] = Number(value);
-      }
-    });
-    message.longLookup = {};
-    Object.entries(object.longLookup ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.longLookup[key] = Long.fromValue(value);
-      }
-    });
+    message.nameLookup = Object.entries(object.nameLookup ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = String(value);
+        }
+        return acc;
+      },
+      {}
+    );
+    message.intLookup = Object.entries(object.intLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Number(value);
+        }
+        return acc;
+      },
+      {}
+    );
+    message.longLookup = Object.entries(object.longLookup ?? {}).reduce<{ [key: string]: Long }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = Long.fromValue(value);
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
diff --git a/integration/simple-optionals/simple.ts b/integration/simple-optionals/simple.ts
index 5b205c05b..6108c6ad8 100644
--- a/integration/simple-optionals/simple.ts
+++ b/integration/simple-optionals/simple.ts
@@ -892,18 +892,27 @@ export const SimpleWithMap = {
 
   fromJSON(object: any): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      message.entitiesById[Number(key)] = Entity.fromJSON(value);
-    });
-    message.nameLookup = {};
-    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
-      message.nameLookup[key] = String(value);
-    });
-    message.intLookup = {};
-    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
-      message.intLookup[Number(key)] = Number(value);
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Entity.fromJSON(value);
+        return acc;
+      },
+      {}
+    );
+    message.nameLookup = Object.entries(object.nameLookup ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        acc[key] = String(value);
+        return acc;
+      },
+      {}
+    );
+    message.intLookup = Object.entries(object.intLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Number(value);
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -932,24 +941,33 @@ export const SimpleWithMap = {
 
   fromPartial(object: DeepPartial<SimpleWithMap>): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.entitiesById[Number(key)] = Entity.fromPartial(value);
-      }
-    });
-    message.nameLookup = {};
-    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.nameLookup[key] = String(value);
-      }
-    });
-    message.intLookup = {};
-    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.intLookup[Number(key)] = Number(value);
-      }
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Entity.fromPartial(value);
+        }
+        return acc;
+      },
+      {}
+    );
+    message.nameLookup = Object.entries(object.nameLookup ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = String(value);
+        }
+        return acc;
+      },
+      {}
+    );
+    message.intLookup = Object.entries(object.intLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Number(value);
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
@@ -1156,10 +1174,13 @@ export const SimpleWithSnakeCaseMap = {
 
   fromJSON(object: any): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      message.entitiesById[Number(key)] = Entity.fromJSON(value);
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Entity.fromJSON(value);
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -1176,12 +1197,15 @@ export const SimpleWithSnakeCaseMap = {
 
   fromPartial(object: DeepPartial<SimpleWithSnakeCaseMap>): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.entitiesById[Number(key)] = Entity.fromPartial(value);
-      }
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Entity.fromPartial(value);
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
diff --git a/integration/simple-snake/simple.ts b/integration/simple-snake/simple.ts
index c51d4c1f3..4ce1a42aa 100644
--- a/integration/simple-snake/simple.ts
+++ b/integration/simple-snake/simple.ts
@@ -892,18 +892,27 @@ export const SimpleWithMap = {
 
   fromJSON(object: any): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      message.entitiesById[Number(key)] = Entity.fromJSON(value);
-    });
-    message.nameLookup = {};
-    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
-      message.nameLookup[key] = String(value);
-    });
-    message.intLookup = {};
-    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
-      message.intLookup[Number(key)] = Number(value);
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Entity.fromJSON(value);
+        return acc;
+      },
+      {}
+    );
+    message.nameLookup = Object.entries(object.nameLookup ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        acc[key] = String(value);
+        return acc;
+      },
+      {}
+    );
+    message.intLookup = Object.entries(object.intLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Number(value);
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -932,24 +941,33 @@ export const SimpleWithMap = {
 
   fromPartial(object: DeepPartial<SimpleWithMap>): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.entitiesById[Number(key)] = Entity.fromPartial(value);
-      }
-    });
-    message.nameLookup = {};
-    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.nameLookup[key] = String(value);
-      }
-    });
-    message.intLookup = {};
-    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.intLookup[Number(key)] = Number(value);
-      }
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Entity.fromPartial(value);
+        }
+        return acc;
+      },
+      {}
+    );
+    message.nameLookup = Object.entries(object.nameLookup ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = String(value);
+        }
+        return acc;
+      },
+      {}
+    );
+    message.intLookup = Object.entries(object.intLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Number(value);
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
@@ -1156,10 +1174,13 @@ export const SimpleWithSnakeCaseMap = {
 
   fromJSON(object: any): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
-    message.entities_by_id = {};
-    Object.entries(object.entities_by_id ?? {}).forEach(([key, value]) => {
-      message.entities_by_id[Number(key)] = Entity.fromJSON(value);
-    });
+    message.entities_by_id = Object.entries(object.entities_by_id ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Entity.fromJSON(value);
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -1176,12 +1197,15 @@ export const SimpleWithSnakeCaseMap = {
 
   fromPartial(object: DeepPartial<SimpleWithSnakeCaseMap>): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
-    message.entities_by_id = {};
-    Object.entries(object.entities_by_id ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.entities_by_id[Number(key)] = Entity.fromPartial(value);
-      }
-    });
+    message.entities_by_id = Object.entries(object.entities_by_id ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Entity.fromPartial(value);
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
diff --git a/integration/simple-unrecognized-enum/simple.ts b/integration/simple-unrecognized-enum/simple.ts
index 9634d65e4..d5d6ac01b 100644
--- a/integration/simple-unrecognized-enum/simple.ts
+++ b/integration/simple-unrecognized-enum/simple.ts
@@ -883,18 +883,27 @@ export const SimpleWithMap = {
 
   fromJSON(object: any): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      message.entitiesById[Number(key)] = Entity.fromJSON(value);
-    });
-    message.nameLookup = {};
-    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
-      message.nameLookup[key] = String(value);
-    });
-    message.intLookup = {};
-    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
-      message.intLookup[Number(key)] = Number(value);
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Entity.fromJSON(value);
+        return acc;
+      },
+      {}
+    );
+    message.nameLookup = Object.entries(object.nameLookup ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        acc[key] = String(value);
+        return acc;
+      },
+      {}
+    );
+    message.intLookup = Object.entries(object.intLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Number(value);
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -923,24 +932,33 @@ export const SimpleWithMap = {
 
   fromPartial(object: DeepPartial<SimpleWithMap>): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.entitiesById[Number(key)] = Entity.fromPartial(value);
-      }
-    });
-    message.nameLookup = {};
-    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.nameLookup[key] = String(value);
-      }
-    });
-    message.intLookup = {};
-    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.intLookup[Number(key)] = Number(value);
-      }
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Entity.fromPartial(value);
+        }
+        return acc;
+      },
+      {}
+    );
+    message.nameLookup = Object.entries(object.nameLookup ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = String(value);
+        }
+        return acc;
+      },
+      {}
+    );
+    message.intLookup = Object.entries(object.intLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Number(value);
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
@@ -1147,10 +1165,13 @@ export const SimpleWithSnakeCaseMap = {
 
   fromJSON(object: any): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      message.entitiesById[Number(key)] = Entity.fromJSON(value);
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Entity.fromJSON(value);
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -1167,12 +1188,15 @@ export const SimpleWithSnakeCaseMap = {
 
   fromPartial(object: DeepPartial<SimpleWithSnakeCaseMap>): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.entitiesById[Number(key)] = Entity.fromPartial(value);
-      }
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Entity.fromPartial(value);
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
diff --git a/integration/simple/simple.ts b/integration/simple/simple.ts
index 83eff8844..93d273821 100644
--- a/integration/simple/simple.ts
+++ b/integration/simple/simple.ts
@@ -1035,34 +1035,54 @@ export const SimpleWithMap = {
 
   fromJSON(object: any): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      message.entitiesById[Number(key)] = Entity.fromJSON(value);
-    });
-    message.nameLookup = {};
-    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
-      message.nameLookup[key] = String(value);
-    });
-    message.intLookup = {};
-    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
-      message.intLookup[Number(key)] = Number(value);
-    });
-    message.mapOfTimestamps = {};
-    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
-      message.mapOfTimestamps[key] = fromJsonTimestamp(value);
-    });
-    message.mapOfBytes = {};
-    Object.entries(object.mapOfBytes ?? {}).forEach(([key, value]) => {
-      message.mapOfBytes[key] = bytesFromBase64(value as string);
-    });
-    message.mapOfStringValues = {};
-    Object.entries(object.mapOfStringValues ?? {}).forEach(([key, value]) => {
-      message.mapOfStringValues[key] = value as string | undefined;
-    });
-    message.longLookup = {};
-    Object.entries(object.longLookup ?? {}).forEach(([key, value]) => {
-      message.longLookup[Number(key)] = Number(value);
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Entity.fromJSON(value);
+        return acc;
+      },
+      {}
+    );
+    message.nameLookup = Object.entries(object.nameLookup ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        acc[key] = String(value);
+        return acc;
+      },
+      {}
+    );
+    message.intLookup = Object.entries(object.intLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Number(value);
+        return acc;
+      },
+      {}
+    );
+    message.mapOfTimestamps = Object.entries(object.mapOfTimestamps ?? {}).reduce<{ [key: string]: Date }>(
+      (acc, [key, value]) => {
+        acc[key] = fromJsonTimestamp(value);
+        return acc;
+      },
+      {}
+    );
+    message.mapOfBytes = Object.entries(object.mapOfBytes ?? {}).reduce<{ [key: string]: Uint8Array }>(
+      (acc, [key, value]) => {
+        acc[key] = bytesFromBase64(value as string);
+        return acc;
+      },
+      {}
+    );
+    message.mapOfStringValues = Object.entries(object.mapOfStringValues ?? {}).reduce<{
+      [key: string]: string | undefined;
+    }>((acc, [key, value]) => {
+      acc[key] = value as string | undefined;
+      return acc;
+    }, {});
+    message.longLookup = Object.entries(object.longLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Number(value);
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -1115,48 +1135,68 @@ export const SimpleWithMap = {
 
   fromPartial(object: DeepPartial<SimpleWithMap>): SimpleWithMap {
     const message = { ...baseSimpleWithMap } as SimpleWithMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.entitiesById[Number(key)] = Entity.fromPartial(value);
-      }
-    });
-    message.nameLookup = {};
-    Object.entries(object.nameLookup ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.nameLookup[key] = String(value);
-      }
-    });
-    message.intLookup = {};
-    Object.entries(object.intLookup ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.intLookup[Number(key)] = Number(value);
-      }
-    });
-    message.mapOfTimestamps = {};
-    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.mapOfTimestamps[key] = value;
-      }
-    });
-    message.mapOfBytes = {};
-    Object.entries(object.mapOfBytes ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.mapOfBytes[key] = value;
-      }
-    });
-    message.mapOfStringValues = {};
-    Object.entries(object.mapOfStringValues ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.mapOfStringValues[key] = value;
-      }
-    });
-    message.longLookup = {};
-    Object.entries(object.longLookup ?? {}).forEach(([key, value]) => {
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Entity.fromPartial(value);
+        }
+        return acc;
+      },
+      {}
+    );
+    message.nameLookup = Object.entries(object.nameLookup ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = String(value);
+        }
+        return acc;
+      },
+      {}
+    );
+    message.intLookup = Object.entries(object.intLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Number(value);
+        }
+        return acc;
+      },
+      {}
+    );
+    message.mapOfTimestamps = Object.entries(object.mapOfTimestamps ?? {}).reduce<{ [key: string]: Date }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = value;
+        }
+        return acc;
+      },
+      {}
+    );
+    message.mapOfBytes = Object.entries(object.mapOfBytes ?? {}).reduce<{ [key: string]: Uint8Array }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = value;
+        }
+        return acc;
+      },
+      {}
+    );
+    message.mapOfStringValues = Object.entries(object.mapOfStringValues ?? {}).reduce<{
+      [key: string]: string | undefined;
+    }>((acc, [key, value]) => {
       if (value !== undefined) {
-        message.longLookup[Number(key)] = Number(value);
+        acc[key] = value;
       }
-    });
+      return acc;
+    }, {});
+    message.longLookup = Object.entries(object.longLookup ?? {}).reduce<{ [key: number]: number }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Number(value);
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
@@ -1590,10 +1630,13 @@ export const SimpleWithSnakeCaseMap = {
 
   fromJSON(object: any): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      message.entitiesById[Number(key)] = Entity.fromJSON(value);
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = Entity.fromJSON(value);
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -1610,12 +1653,15 @@ export const SimpleWithSnakeCaseMap = {
 
   fromPartial(object: DeepPartial<SimpleWithSnakeCaseMap>): SimpleWithSnakeCaseMap {
     const message = { ...baseSimpleWithSnakeCaseMap } as SimpleWithSnakeCaseMap;
-    message.entitiesById = {};
-    Object.entries(object.entitiesById ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.entitiesById[Number(key)] = Entity.fromPartial(value);
-      }
-    });
+    message.entitiesById = Object.entries(object.entitiesById ?? {}).reduce<{ [key: number]: Entity }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = Entity.fromPartial(value);
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
@@ -1710,10 +1756,13 @@ export const SimpleWithMapOfEnums = {
 
   fromJSON(object: any): SimpleWithMapOfEnums {
     const message = { ...baseSimpleWithMapOfEnums } as SimpleWithMapOfEnums;
-    message.enumsById = {};
-    Object.entries(object.enumsById ?? {}).forEach(([key, value]) => {
-      message.enumsById[Number(key)] = value as number;
-    });
+    message.enumsById = Object.entries(object.enumsById ?? {}).reduce<{ [key: number]: StateEnum }>(
+      (acc, [key, value]) => {
+        acc[Number(key)] = value as number;
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -1730,12 +1779,15 @@ export const SimpleWithMapOfEnums = {
 
   fromPartial(object: DeepPartial<SimpleWithMapOfEnums>): SimpleWithMapOfEnums {
     const message = { ...baseSimpleWithMapOfEnums } as SimpleWithMapOfEnums;
-    message.enumsById = {};
-    Object.entries(object.enumsById ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.enumsById[Number(key)] = value as number;
-      }
-    });
+    message.enumsById = Object.entries(object.enumsById ?? {}).reduce<{ [key: number]: StateEnum }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[Number(key)] = value as number;
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
diff --git a/integration/struct/google/protobuf/struct.ts b/integration/struct/google/protobuf/struct.ts
index c7c383d41..20465f053 100644
--- a/integration/struct/google/protobuf/struct.ts
+++ b/integration/struct/google/protobuf/struct.ts
@@ -126,10 +126,13 @@ export const Struct = {
 
   fromJSON(object: any): Struct {
     const message = { ...baseStruct } as Struct;
-    message.fields = {};
-    Object.entries(object.fields ?? {}).forEach(([key, value]) => {
-      message.fields[key] = value as any | undefined;
-    });
+    message.fields = Object.entries(object.fields ?? {}).reduce<{ [key: string]: any | undefined }>(
+      (acc, [key, value]) => {
+        acc[key] = value as any | undefined;
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -146,12 +149,15 @@ export const Struct = {
 
   fromPartial(object: DeepPartial<Struct>): Struct {
     const message = { ...baseStruct } as Struct;
-    message.fields = {};
-    Object.entries(object.fields ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.fields[key] = value;
-      }
-    });
+    message.fields = Object.entries(object.fields ?? {}).reduce<{ [key: string]: any | undefined }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = value;
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
diff --git a/integration/use-date-string/use-date-string.ts b/integration/use-date-string/use-date-string.ts
index 4fce84847..d7e15656f 100644
--- a/integration/use-date-string/use-date-string.ts
+++ b/integration/use-date-string/use-date-string.ts
@@ -85,10 +85,13 @@ export const Todo = {
       object.optionalTimestamp !== undefined && object.optionalTimestamp !== null
         ? String(object.optionalTimestamp)
         : undefined;
-    message.mapOfTimestamps = {};
-    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
-      message.mapOfTimestamps[key] = String(value);
-    });
+    message.mapOfTimestamps = Object.entries(object.mapOfTimestamps ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        acc[key] = String(value);
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -117,12 +120,15 @@ export const Todo = {
     message.timestamp = object.timestamp ?? undefined;
     message.repeatedTimestamp = (object.repeatedTimestamp ?? []).map((e) => e);
     message.optionalTimestamp = object.optionalTimestamp ?? undefined;
-    message.mapOfTimestamps = {};
-    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.mapOfTimestamps[key] = value;
-      }
-    });
+    message.mapOfTimestamps = Object.entries(object.mapOfTimestamps ?? {}).reduce<{ [key: string]: string }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = value;
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
diff --git a/integration/use-date-true/use-date-true.ts b/integration/use-date-true/use-date-true.ts
index 12a5fbd40..172e251c7 100644
--- a/integration/use-date-true/use-date-true.ts
+++ b/integration/use-date-true/use-date-true.ts
@@ -85,10 +85,13 @@ export const Todo = {
       object.optionalTimestamp !== undefined && object.optionalTimestamp !== null
         ? fromJsonTimestamp(object.optionalTimestamp)
         : undefined;
-    message.mapOfTimestamps = {};
-    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
-      message.mapOfTimestamps[key] = fromJsonTimestamp(value);
-    });
+    message.mapOfTimestamps = Object.entries(object.mapOfTimestamps ?? {}).reduce<{ [key: string]: Date }>(
+      (acc, [key, value]) => {
+        acc[key] = fromJsonTimestamp(value);
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -117,12 +120,15 @@ export const Todo = {
     message.timestamp = object.timestamp ?? undefined;
     message.repeatedTimestamp = (object.repeatedTimestamp ?? []).map((e) => e);
     message.optionalTimestamp = object.optionalTimestamp ?? undefined;
-    message.mapOfTimestamps = {};
-    Object.entries(object.mapOfTimestamps ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.mapOfTimestamps[key] = value;
-      }
-    });
+    message.mapOfTimestamps = Object.entries(object.mapOfTimestamps ?? {}).reduce<{ [key: string]: Date }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = value;
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
diff --git a/integration/value/google/protobuf/struct.ts b/integration/value/google/protobuf/struct.ts
index c7c383d41..20465f053 100644
--- a/integration/value/google/protobuf/struct.ts
+++ b/integration/value/google/protobuf/struct.ts
@@ -126,10 +126,13 @@ export const Struct = {
 
   fromJSON(object: any): Struct {
     const message = { ...baseStruct } as Struct;
-    message.fields = {};
-    Object.entries(object.fields ?? {}).forEach(([key, value]) => {
-      message.fields[key] = value as any | undefined;
-    });
+    message.fields = Object.entries(object.fields ?? {}).reduce<{ [key: string]: any | undefined }>(
+      (acc, [key, value]) => {
+        acc[key] = value as any | undefined;
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 
@@ -146,12 +149,15 @@ export const Struct = {
 
   fromPartial(object: DeepPartial<Struct>): Struct {
     const message = { ...baseStruct } as Struct;
-    message.fields = {};
-    Object.entries(object.fields ?? {}).forEach(([key, value]) => {
-      if (value !== undefined) {
-        message.fields[key] = value;
-      }
-    });
+    message.fields = Object.entries(object.fields ?? {}).reduce<{ [key: string]: any | undefined }>(
+      (acc, [key, value]) => {
+        if (value !== undefined) {
+          acc[key] = value;
+        }
+        return acc;
+      },
+      {}
+    );
     return message;
   },
 };
diff --git a/src/main.ts b/src/main.ts
index a3b7991b6..e9f196a9e 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1082,12 +1082,13 @@ function generateFromJson(ctx: Context, fullName: string, messageDesc: Descripto
     // and then use the snippet to handle repeated fields if necessary
     if (isRepeated(field)) {
       if (isMapType(ctx, messageDesc, field)) {
-        chunks.push(code`message.${fieldName} = {};`);
+        const fieldType = toTypeName(ctx, messageDesc, field);
         const i = maybeCastToNumber(ctx, messageDesc, field, 'key');
         chunks.push(code`
-          Object.entries(object.${fieldName} ?? {}).forEach(([key, value]) => {
-            message.${fieldName}[${i}] = ${readSnippet('value')};
-          });
+          message.${fieldName} = Object.entries(object.${fieldName} ?? {}).reduce<${fieldType}>((acc, [key, value]) => {
+            acc[${i}] = ${readSnippet('value')};
+            return acc;
+          }, {});
         `);
       } else if (isAnyValueType(field)) {
         chunks.push(code`
@@ -1301,14 +1302,15 @@ function generateFromPartial(ctx: Context, fullName: string, messageDesc: Descri
     // and then use the snippet to handle repeated fields if necessary
     if (isRepeated(field)) {
       if (isMapType(ctx, messageDesc, field)) {
-        chunks.push(code`message.${fieldName} = {};`);
+        const fieldType = toTypeName(ctx, messageDesc, field);
         const i = maybeCastToNumber(ctx, messageDesc, field, 'key');
         chunks.push(code`
-          Object.entries(object.${fieldName} ?? {}).forEach(([key, value]) => {
+          message.${fieldName} = Object.entries(object.${fieldName} ?? {}).reduce<${fieldType}>((acc, [key, value]) => {
             if (value !== undefined) {
-              message.${fieldName}[${i}] = ${readSnippet('value')};
+              acc[${i}] = ${readSnippet('value')};
             }
-          });
+            return acc;
+          }, {});
         `);
       } else {
         chunks.push(code`