From a88c0133f136eb10699a7c1f56c3d24bc17490fe Mon Sep 17 00:00:00 2001
From: Jordan Eldredge <jeldredge@meta.com>
Date: Mon, 11 Nov 2024 15:45:09 -0800
Subject: [PATCH] Derive @required fieldPath at runtime

Reviewed By: lynnshaoyu

Differential Revision: D65459456

fbshipit-source-id: a6e4788a7fa979a8b3ce5c19781b9390d9d9fd59
---
 packages/relay-runtime/store/RelayReader.js   | 35 ++++++++++++-------
 .../relay-runtime/store/RelayStoreTypes.js    |  4 +--
 packages/relay-runtime/util/ReaderNode.js     |  3 +-
 3 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/packages/relay-runtime/store/RelayReader.js b/packages/relay-runtime/store/RelayReader.js
index 0ab688bcb8f2e..e5ff4191f049d 100644
--- a/packages/relay-runtime/store/RelayReader.js
+++ b/packages/relay-runtime/store/RelayReader.js
@@ -295,18 +295,29 @@ class RelayReader {
     return this._variables[name];
   }
 
-  _maybeReportUnexpectedNull(fieldPath: string, action: 'LOG' | 'THROW') {
+  _maybeReportUnexpectedNull(selection: ReaderRequiredField) {
+    if (selection.action === 'NONE') {
+      return;
+    }
     const owner = this._fragmentName;
 
     if (this._errorResponseFields == null) {
       this._errorResponseFields = [];
     }
 
-    switch (action) {
+    let fieldName: string;
+    if (selection.field.linkedField != null) {
+      fieldName =
+        selection.field.linkedField.alias ?? selection.field.linkedField.name;
+    } else {
+      fieldName = selection.field.alias ?? selection.field.name;
+    }
+
+    switch (selection.action) {
       case 'THROW':
         this._errorResponseFields.push({
           kind: 'missing_required_field.throw',
-          fieldPath,
+          fieldPath: fieldName,
           owner,
           handled: false,
         });
@@ -314,12 +325,12 @@ class RelayReader {
       case 'LOG':
         this._errorResponseFields.push({
           kind: 'missing_required_field.log',
-          fieldPath,
+          fieldPath: fieldName,
           owner,
         });
         return;
       default:
-        (action: empty);
+        (selection.action: empty);
     }
   }
 
@@ -328,10 +339,7 @@ class RelayReader {
     value: mixed,
   ): boolean /*should continue to siblings*/ {
     if (value == null) {
-      const {action} = selection;
-      if (action !== 'NONE') {
-        this._maybeReportUnexpectedNull(selection.path, action);
-      }
+      this._maybeReportUnexpectedNull(selection);
       // We are going to throw, or our parent is going to get nulled out.
       // Either way, sibling values are going to be ignored, so we can
       // bail early here as an optimization.
@@ -1137,8 +1145,9 @@ class RelayReader {
    * Similarly, when creating field errors, we simply initialize the `fieldPath`
    * as the direct field name.
    *
-   * Today we only use this apporach for `missing_expected_data` errors, but we
-   * intend to broaden it to handle all field error paths.
+   * Today we only use this apporach for `missing_expected_data` and
+   * `missing_required_field` errors, but we intend to broaden it to handle all
+   * field error paths.
    */
   _prependPreviousErrors(
     prevErrors: ?Array<ErrorResponseField>,
@@ -1150,7 +1159,9 @@ class RelayReader {
         if (
           event.owner === this._fragmentName &&
           (event.kind === 'missing_expected_data.throw' ||
-            event.kind === 'missing_expected_data.log')
+            event.kind === 'missing_expected_data.log' ||
+            event.kind === 'missing_required_field.throw' ||
+            event.kind === 'missing_required_field.log')
         ) {
           event.fieldPath = `${fieldNameOrIndex}.${event.fieldPath}`;
         }
diff --git a/packages/relay-runtime/store/RelayStoreTypes.js b/packages/relay-runtime/store/RelayStoreTypes.js
index 6b1f03b443460..b838e1e1acc99 100644
--- a/packages/relay-runtime/store/RelayStoreTypes.js
+++ b/packages/relay-runtime/store/RelayStoreTypes.js
@@ -1311,7 +1311,7 @@ export type MissingExpectedDataThrowEvent = {
 export type MissingRequiredFieldLogEvent = {
   +kind: 'missing_required_field.log',
   +owner: string,
-  +fieldPath: string,
+  fieldPath: string, // Purposefully mutable to allow lazy construction in RelayReader
 };
 
 /**
@@ -1328,7 +1328,7 @@ export type MissingRequiredFieldLogEvent = {
 export type MissingRequiredFieldThrowEvent = {
   +kind: 'missing_required_field.throw',
   +owner: string,
-  +fieldPath: string,
+  fieldPath: string, // Purposefully mutable to allow lazy construction in RelayReader
   +handled: boolean,
 };
 
diff --git a/packages/relay-runtime/util/ReaderNode.js b/packages/relay-runtime/util/ReaderNode.js
index 3024313b6fa9a..4ec3574d395d6 100644
--- a/packages/relay-runtime/util/ReaderNode.js
+++ b/packages/relay-runtime/util/ReaderNode.js
@@ -235,7 +235,8 @@ export type ReaderRequiredField = {
   +kind: 'RequiredField',
   +field: ReaderField | ReaderClientEdge,
   +action: RequiredFieldAction,
-  +path: string,
+  // TODO: This field is not used any more, we should be able to remove it.
+  +path?: mixed,
 };
 
 export type CatchFieldTo = 'RESULT' | 'NULL';