feat: make get_origin_and_cast

This fixes the type-checker error raised while accessing RequestBuilder[T].__origin__
supabase · Sep 19, 2023 · ab2256f · ab2256f
1 parent 2231d2d
commit ab2256f
Show file tree

Hide file tree

Showing 3 changed files with 29 additions and 27 deletions.
diff --git a/postgrest/_async/request_builder.py b/postgrest/_async/request_builder.py
@@ -20,7 +20,7 @@
 )
 from ..exceptions import APIError, generate_default_error_message
 from ..types import ReturnMethod
-from ..utils import AsyncClient
+from ..utils import AsyncClient, get_origin_and_cast
 
 _ReturnT = TypeVar("_ReturnT")
 
@@ -154,13 +154,10 @@ def __init__(
         params: QueryParams,
         json: dict,
     ) -> None:
-        # Generic[T] is an instance of typing._GenericAlias, so doing Generic[T].__init__
-        # tries to call _GenericAlias.__init__ - which is the wrong method
-        # The __origin__ attribute of the _GenericAlias is the actual class
-        BaseFilterRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(BaseFilterRequestBuilder[_ReturnT]).__init__(
             self, session, headers, params
         )
-        AsyncQueryRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(AsyncQueryRequestBuilder[_ReturnT]).__init__(
             self, session, path, http_method, headers, params, json
         )
 
@@ -178,10 +175,10 @@ def __init__(
         params: QueryParams,
         json: dict,
     ) -> None:
-        BaseFilterRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(BaseFilterRequestBuilder[_ReturnT]).__init__(
             self, session, headers, params
         )
-        AsyncSingleRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(AsyncSingleRequestBuilder[_ReturnT]).__init__(
             self, session, path, http_method, headers, params, json
         )
 
@@ -197,13 +194,10 @@ def __init__(
         params: QueryParams,
         json: dict,
     ) -> None:
-        # Generic[T] is an instance of typing._GenericAlias, so doing Generic[T].__init__
-        # tries to call _GenericAlias.__init__ - which is the wrong method
-        # The __origin__ attribute of the _GenericAlias is the actual class
-        BaseSelectRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(BaseSelectRequestBuilder[_ReturnT]).__init__(
             self, session, headers, params
         )
-        AsyncQueryRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(AsyncQueryRequestBuilder[_ReturnT]).__init__(
             self, session, path, http_method, headers, params, json
         )
 

diff --git a/postgrest/_sync/request_builder.py b/postgrest/_sync/request_builder.py
@@ -20,7 +20,7 @@
 )
 from ..exceptions import APIError, generate_default_error_message
 from ..types import ReturnMethod
-from ..utils import SyncClient
+from ..utils import SyncClient, get_origin_and_cast
 
 _ReturnT = TypeVar("_ReturnT")
 
@@ -154,13 +154,10 @@ def __init__(
         params: QueryParams,
         json: dict,
     ) -> None:
-        # Generic[T] is an instance of typing._GenericAlias, so doing Generic[T].__init__
-        # tries to call _GenericAlias.__init__ - which is the wrong method
-        # The __origin__ attribute of the _GenericAlias is the actual class
-        BaseFilterRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(BaseFilterRequestBuilder[_ReturnT]).__init__(
             self, session, headers, params
         )
-        SyncQueryRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(SyncQueryRequestBuilder[_ReturnT]).__init__(
             self, session, path, http_method, headers, params, json
         )
 
@@ -178,10 +175,10 @@ def __init__(
         params: QueryParams,
         json: dict,
     ) -> None:
-        BaseFilterRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(BaseFilterRequestBuilder[_ReturnT]).__init__(
             self, session, headers, params
         )
-        SyncSingleRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(SyncSingleRequestBuilder[_ReturnT]).__init__(
             self, session, path, http_method, headers, params, json
         )
 
@@ -197,13 +194,10 @@ def __init__(
         params: QueryParams,
         json: dict,
     ) -> None:
-        # Generic[T] is an instance of typing._GenericAlias, so doing Generic[T].__init__
-        # tries to call _GenericAlias.__init__ - which is the wrong method
-        # The __origin__ attribute of the _GenericAlias is the actual class
-        BaseSelectRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(BaseSelectRequestBuilder[_ReturnT]).__init__(
             self, session, headers, params
         )
-        SyncQueryRequestBuilder[_ReturnT].__origin__.__init__(
+        get_origin_and_cast(SyncQueryRequestBuilder[_ReturnT]).__init__(
             self, session, path, http_method, headers, params, json
         )
 

diff --git a/postgrest/utils.py b/postgrest/utils.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from typing import Any
+from typing import Any, TypeVar, cast, get_origin
 
 from httpx import AsyncClient  # noqa: F401
 from httpx import Client as BaseClient  # noqa: F401
@@ -21,3 +21,17 @@ def sanitize_param(param: Any) -> str:
 
 def sanitize_pattern_param(pattern: str) -> str:
     return sanitize_param(pattern.replace("%", "*"))
+
+
+_T = TypeVar("_T")
+
+
+def get_origin_and_cast(typ: type[type[_T]]) -> type[_T]:
+    # Base[T] is an instance of typing._GenericAlias, so doing Base[T].__init__
+    # tries to call _GenericAlias.__init__ - which is the wrong method
+    # get_origin(Base[T]) returns Base
+    # This function casts Base back to Base[T] to maintain type-safety
+    # while still allowing us to access the methods of `Base` at runtime
+    # See: definitions of request builders that use multiple-inheritance
+    # like AsyncFilterRequestBuilder
+    return cast(type[_T], get_origin(typ))