Merge d2ec5d6620 into 1d434dec47

fastapi/dependencies/protocols.py

@@ -0,0 +1,11 @@
+from typing import Any, Tuple
+
+from typing_extensions import Protocol
+
+
+class GenericTypeProtocol(Protocol):
+    class OriginTypeProtocol(Protocol):
+        __parameters__: Tuple[Any]
+
+    __origin__: OriginTypeProtocol
+    __args__: Tuple[Any]

fastapi/dependencies/utils.py

@@ -52,6 +52,7 @@ from fastapi.concurrency import (
     contextmanager_in_threadpool,
 )
 from fastapi.dependencies.models import Dependant, SecurityRequirement
+from fastapi.dependencies.protocols import GenericTypeProtocol
 from fastapi.logger import logger
 from fastapi.security.base import SecurityBase
 from fastapi.security.oauth2 import OAuth2, SecurityScopes
@@ -228,7 +229,32 @@ def get_flat_params(dependant: Dependant) -> List[ModelField]:
     return path_params + query_params + header_params + cookie_params
 
 
+def is_generic_type(obj: Any) -> bool:
+    return hasattr(obj, "__origin__") and hasattr(obj, "__args__")
+
+
+def substitute_generic_type(annotation: Any, typevars: Dict[str, Any]) -> Any:
+    collection_shells = {list: List, set: List, dict: Dict, tuple: Tuple}
+    if is_generic_type(annotation):
+        args = tuple(
+            substitute_generic_type(arg, typevars) for arg in annotation.__args__
+        )
+        annotation = collection_shells.get(annotation.__origin__, annotation)
+        return annotation[args]
+    return typevars.get(annotation.__name__, annotation)
+
+
 def get_typed_signature(call: Callable[..., Any]) -> inspect.Signature:
+    typevars = None
+    if is_generic_type(call):
+        generic: GenericTypeProtocol = cast(GenericTypeProtocol, call)
+        origin: Any = generic.__origin__
+        typevars = {
+            typevar.__name__: value
+            for typevar, value in zip(origin.__parameters__, generic.__args__)
+        }
+        call = origin.__init__
+
     signature = inspect.signature(call)
     globalns = getattr(call, "__globals__", {})
     typed_params = [
@@ -236,18 +262,25 @@ def get_typed_signature(call: Callable[..., Any]) -> inspect.Signature:
             name=param.name,
             kind=param.kind,
             default=param.default,
-            annotation=get_typed_annotation(param.annotation, globalns),
+            annotation=get_typed_annotation(param.annotation, globalns, typevars),
         )
         for param in signature.parameters.values()
+        if param.name != "self"
     ]
     typed_signature = inspect.Signature(typed_params)
     return typed_signature
 
 
-def get_typed_annotation(annotation: Any, globalns: Dict[str, Any]) -> Any:
+def get_typed_annotation(
+    annotation: Any,
+    globalns: Dict[str, Any],
+    typevars: Optional[Dict[str, type]] = None,
+) -> Any:
     if isinstance(annotation, str):
         annotation = ForwardRef(annotation)
         annotation = evaluate_forwardref(annotation, globalns, globalns)
+    if typevars:
+        annotation = substitute_generic_type(annotation, typevars)
     return annotation
 
 

tests/test_dependency_generic_class.py

@@ -0,0 +1,66 @@
+from typing import Dict, Generic, List, TypeVar
+
+from fastapi import Depends, FastAPI
+from starlette.testclient import TestClient
+
+T = TypeVar("T")
+C = TypeVar("C")
+
+
+class FirstGenericType(Generic[T]):
+    def __init__(self, simple: T, lst: List[T]):
+        self.simple = simple
+        self.lst = lst
+
+
+class SecondGenericType(Generic[T, C]):
+    def __init__(
+        self,
+        simple: T,
+        lst: List[T],
+        dct: Dict[T, C],
+        custom_class: FirstGenericType[T] = Depends(),
+    ):
+        self.simple = simple
+        self.lst = lst
+        self.dct = dct
+        self.custom_class = custom_class
+
+
+app = FastAPI()
+
+
+@app.post("/test_generic_class")
+def depend_generic_type(obj: SecondGenericType[str, int] = Depends()):
+    return {
+        "simple": obj.simple,
+        "lst": obj.lst,
+        "dct": obj.dct,
+        "custom_class": {
+            "simple": obj.custom_class.simple,
+            "lst": obj.custom_class.lst,
+        },
+    }
+
+
+client = TestClient(app)
+
+
+def test_generic_class_dependency():
+    response = client.post(
+        "/test_generic_class?simple=simple",
+        json={
+            "lst": ["string_1", "string_2"],
+            "dct": {"key": 1},
+        },
+    )
+    assert response.status_code == 200, response.json()
+    assert response.json() == {
+        "custom_class": {
+            "lst": ["string_1", "string_2"],
+            "simple": "simple",
+        },
+        "lst": ["string_1", "string_2"],
+        "dct": {"key": 1},
+        "simple": "simple",
+    }