🔖 Release version 0.41.0

Pipfile

@@ -25,7 +25,7 @@ sqlalchemy = "*"
 uvicorn = "*"
 
 [packages]
-starlette = "==0.12.8"
+starlette = "==0.12.9"
 pydantic = "==0.32.2"
 databases = {extras = ["sqlite"],version = "*"}
 hypercorn = "*"

docs/release-notes.md

@@ -1,5 +1,20 @@
 ## Latest changes
 
+## 0.41.0
+
+* Upgrade required Starlette to `0.12.9`, the new range is `>=0.12.9,<=0.12.9`.
+    * Add `State` to FastAPI apps at `app.state`.
+    * PR [#593](https://github.com/tiangolo/fastapi/pull/593).
+* Improve handling of custom classes for `Request`s and `APIRoute`s.
+    * This helps to more easily solve use cases like:
+        * Reading a body before and/or after a request (equivalent to a middleware).
+        * Run middleware-like code only for a subset of *path operations*.
+        * Process a request before passing it to a *path operation function*. E.g. decompressing, deserializing, etc.
+        * Processing a response after being generated by *path operation functions* but before returning it. E.g. adding custom headers, logging, adding extra metadata.
+    * New docs section: [Custom Request and APIRoute class](https://fastapi.tiangolo.com/tutorial/custom-request-and-route/).
+    * PR [#589](https://github.com/tiangolo/fastapi/pull/589) by [@dmontagu](https://github.com/dmontagu).
+* Fix preserving custom route class in routers when including other sub-routers. PR [#538](https://github.com/tiangolo/fastapi/pull/538) by [@dmontagu](https://github.com/dmontagu).
+
 ## 0.40.0
 
 * Add notes to docs about installing `python-multipart` when using forms. PR [#574](https://github.com/tiangolo/fastapi/pull/574) by [@sliptonic](https://github.com/sliptonic).

docs/src/custom_request_and_route/tutorial001.py

@@ -0,0 +1,37 @@
+import gzip
+from typing import Callable, List
+
+from fastapi import Body, FastAPI
+from fastapi.routing import APIRoute
+from starlette.requests import Request
+from starlette.responses import Response
+
+
+class GzipRequest(Request):
+    async def body(self) -> bytes:
+        if not hasattr(self, "_body"):
+            body = await super().body()
+            if "gzip" in self.headers.getlist("Content-Encoding"):
+                body = gzip.decompress(body)
+            self._body = body
+        return self._body
+
+
+class GzipRoute(APIRoute):
+    def get_route_handler(self) -> Callable:
+        original_route_handler = super().get_route_handler()
+
+        async def custom_route_handler(request: Request) -> Response:
+            request = GzipRequest(request.scope, request.receive)
+            return await original_route_handler(request)
+
+        return custom_route_handler
+
+
+app = FastAPI()
+app.router.route_class = GzipRoute
+
+
+@app.post("/sum")
+async def sum_numbers(numbers: List[int] = Body(...)):
+    return {"sum": sum(numbers)}

docs/src/custom_request_and_route/tutorial002.py

@@ -0,0 +1,31 @@
+from typing import Callable, List
+
+from fastapi import Body, FastAPI, HTTPException
+from fastapi.exceptions import RequestValidationError
+from fastapi.routing import APIRoute
+from starlette.requests import Request
+from starlette.responses import Response
+
+
+class ValidationErrorLoggingRoute(APIRoute):
+    def get_route_handler(self) -> Callable:
+        original_route_handler = super().get_route_handler()
+
+        async def custom_route_handler(request: Request) -> Response:
+            try:
+                return await original_route_handler(request)
+            except RequestValidationError as exc:
+                body = await request.body()
+                detail = {"errors": exc.errors(), "body": body.decode()}
+                raise HTTPException(status_code=422, detail=detail)
+
+        return custom_route_handler
+
+
+app = FastAPI()
+app.router.route_class = ValidationErrorLoggingRoute
+
+
+@app.post("/")
+async def sum_numbers(numbers: List[int] = Body(...)):
+    return sum(numbers)

docs/src/custom_request_and_route/tutorial003.py

@@ -0,0 +1,41 @@
+import time
+from typing import Callable
+
+from fastapi import APIRouter, FastAPI
+from fastapi.routing import APIRoute
+from starlette.requests import Request
+from starlette.responses import Response
+
+
+class TimedRoute(APIRoute):
+    def get_route_handler(self) -> Callable:
+        original_route_handler = super().get_route_handler()
+
+        async def custom_route_handler(request: Request) -> Response:
+            before = time.time()
+            response: Response = await original_route_handler(request)
+            duration = time.time() - before
+            response.headers["X-Response-Time"] = str(duration)
+            print(f"route duration: {duration}")
+            print(f"route response: {response}")
+            print(f"route response headers: {response.headers}")
+            return response
+
+        return custom_route_handler
+
+
+app = FastAPI()
+router = APIRouter(route_class=TimedRoute)
+
+
+@app.get("/")
+async def not_timed():
+    return {"message": "Not timed"}
+
+
+@router.get("/timed")
+async def timed():
+    return {"message": "It's the time of my life"}
+
+
+app.include_router(router)

docs/tutorial/custom-request-and-route.md

@@ -0,0 +1,100 @@
+In some cases, you may want to override the logic used by the `Request` and `APIRoute` classes.
+
+In particular, this may be a good alternative to logic in a middleware.
+
+For example, if you want to read or manipulate the request body before it is processed by your application.
+
+!!! danger
+    This is an "advanced" feature.
+
+    If you are just starting with **FastAPI** you might want to skip this section.
+
+## Use cases
+
+Some use cases include:
+
+* Converting non-JSON request bodies to JSON (e.g. [`msgpack`](https://msgpack.org/index.html)).
+* Decompressing gzip-compressed request bodies.
+* Automatically logging all request bodies.
+* Accessing the request body in an exception handler.
+
+## Handling custom request body encodings
+
+Let's see how to make use of a custom `Request` subclass to decompress gzip requests.
+
+And an `APIRoute` subclass to use that custom request class.
+
+### Create a custom `GzipRequest` class
+
+First, we create a `GzipRequest` class, which will overwrite the `Request.body()` method to decompress the body in the presence of an appropriate header.
+
+If there's no `gzip` in the header, it will not try to decompress the body.
+
+That way, the same route class can handle gzip compressed or uncompressed requests.
+
+```Python hl_lines="10 11 12 13 14 15 16 17"
+{!./src/custom_request_and_route/tutorial001.py!}
+```
+
+### Create a custom `GzipRoute` class
+
+Next, we create a custom subclass of `fastapi.routing.APIRoute` that will make use of the `GzipRequest`.
+
+This time, it will overwrite the method `APIRoute.get_route_handler()`.
+
+This method returns a function. And that function is what will receive a request and return a response.
+
+Here we use it to create a `GzipRequest` from the original request.
+
+```Python hl_lines="20 21 22 23 24 25 26 27 28"
+{!./src/custom_request_and_route/tutorial001.py!}
+```
+
+!!! note "Technical Details"
+    A `Request` has a `request.scope` attribute, that's just a Python `dict` containing the metadata related to the request.
+
+    A `Request` also has a `request.receive`, that's a function to "receive" the body of the request.
+
+    The `scope` `dict` and `receive` function are both part of the ASGI specification.
+
+    And those two things, `scope` and `receive`, are what is needed to create a new `Request` instance.
+
+    To learn more about the `Request` check <a href="https://www.starlette.io/requests/" target="_blank">Starlette's docs about Requests</a>.
+
+The only thing the function returned by `GzipRequest.get_route_handler` does differently is convert the `Request` to a `GzipRequest`.
+
+Doing this, our `GzipRequest` will take care of decompressing the data (if necessary) before passing it to our *path operations*.
+
+After that, all of the processing logic is the same.
+
+But because of our changes in `GzipRequest.body`, the request body will be automatically decompressed when it is loaded by **FastAPI** when needed.
+
+## Accessing the request body in an exception handler
+
+We can also use this same approach to access the request body in an exception handler.
+
+All we need to do is handle the request inside a `try`/`except` block:
+
+```Python hl_lines="15 17"
+{!./src/custom_request_and_route/tutorial002.py!}
+```
+
+If an exception occurs, the`Request` instance will still be in scope, so we can read and make use of the request body when handling the error:
+
+```Python hl_lines="18 19 20"
+{!./src/custom_request_and_route/tutorial002.py!}
+```
+
+## Custom `APIRoute` class in a router
+
+You can also set the `route_class` parameter of an `APIRouter`:
+
+```Python hl_lines="25"
+{!./src/custom_request_and_route/tutorial003.py!}
+```
+
+In this example, the *path operations* under the `router` will use the custom `TimedRoute` class, and will have an extra `X-Response-Time` header in the response with the time it took to generate the response:
+
+```Python hl_lines="15 16 17 18 19"
+{!./src/custom_request_and_route/tutorial003.py!}
+```

fastapi/__init__.py

@@ -1,6 +1,6 @@
 """FastAPI framework, high performance, easy to learn, fast to code, ready for production"""
 
-__version__ = "0.40.0"
+__version__ = "0.41.0"
 
 from starlette.background import BackgroundTasks
 

fastapi/applications.py

@@ -15,6 +15,7 @@ from fastapi.openapi.docs import (
 from fastapi.openapi.utils import get_openapi
 from fastapi.params import Depends
 from starlette.applications import Starlette
+from starlette.datastructures import State
 from starlette.exceptions import ExceptionMiddleware, HTTPException
 from starlette.middleware.errors import ServerErrorMiddleware
 from starlette.requests import Request
@@ -42,6 +43,7 @@ class FastAPI(Starlette):
     ) -> None:
         self.default_response_class = default_response_class
         self._debug = debug
+        self.state = State()
         self.router: routing.APIRouter = routing.APIRouter(
             routes, dependency_overrides_provider=self
         )

fastapi/routing.py

@@ -65,7 +65,7 @@ def serialize_response(
         return jsonable_encoder(response)
 
 
-def get_app(
+def get_request_handler(
     dependant: Dependant,
     body_field: Field = None,
     status_code: int = 200,
@@ -294,19 +294,20 @@ class APIRoute(routing.Route):
             )
         self.body_field = get_body_field(dependant=self.dependant, name=self.unique_id)
         self.dependency_overrides_provider = dependency_overrides_provider
-        self.app = request_response(
-            get_app(
-                dependant=self.dependant,
-                body_field=self.body_field,
-                status_code=self.status_code,
-                response_class=self.response_class or JSONResponse,
-                response_field=self.secure_cloned_response_field,
-                response_model_include=self.response_model_include,
-                response_model_exclude=self.response_model_exclude,
-                response_model_by_alias=self.response_model_by_alias,
-                response_model_skip_defaults=self.response_model_skip_defaults,
-                dependency_overrides_provider=self.dependency_overrides_provider,
-            )
+        self.app = request_response(self.get_route_handler())
+
+    def get_route_handler(self) -> Callable:
+        return get_request_handler(
+            dependant=self.dependant,
+            body_field=self.body_field,
+            status_code=self.status_code,
+            response_class=self.response_class or JSONResponse,
+            response_field=self.secure_cloned_response_field,
+            response_model_include=self.response_model_include,
+            response_model_exclude=self.response_model_exclude,
+            response_model_by_alias=self.response_model_by_alias,
+            response_model_skip_defaults=self.response_model_skip_defaults,
+            dependency_overrides_provider=self.dependency_overrides_provider,
         )
 
 
@@ -348,8 +349,10 @@ class APIRouter(routing.Router):
         include_in_schema: bool = True,
         response_class: Type[Response] = None,
         name: str = None,
+        route_class_override: Optional[Type[APIRoute]] = None,
     ) -> None:
-        route = self.route_class(
+        route_class = route_class_override or self.route_class
+        route = route_class(
             path,
             endpoint=endpoint,
             response_model=response_model,
@@ -487,6 +490,7 @@ class APIRouter(routing.Router):
                     include_in_schema=route.include_in_schema,
                     response_class=route.response_class or default_response_class,
                     name=route.name,
+                    route_class_override=type(route),
                 )
             elif isinstance(route, routing.Route):
                 self.add_route(

mkdocs.yml

@@ -81,6 +81,7 @@ nav:
         - GraphQL: 'tutorial/graphql.md'
         - WebSockets: 'tutorial/websockets.md'
         - 'Events: startup - shutdown': 'tutorial/events.md'
+        - Custom Request and APIRoute class: 'tutorial/custom-request-and-route.md'
         - Testing: 'tutorial/testing.md'
         - Testing Dependencies with Overrides: 'tutorial/testing-dependencies.md'
         - Debugging: 'tutorial/debugging.md'

pyproject.toml

@@ -19,7 +19,7 @@ classifiers = [
     "Topic :: Internet :: WWW/HTTP :: HTTP Servers",
 ]
 requires = [
-    "starlette >=0.11.1,<=0.12.8",
+    "starlette >=0.12.9,<=0.12.9",
     "pydantic >=0.32.2,<=0.32.2"
 ]
 description-file = "README.md"

tests/test_custom_route_class.py

@@ -0,0 +1,114 @@
+import pytest
+from fastapi import APIRouter, FastAPI
+from fastapi.routing import APIRoute
+from starlette.testclient import TestClient
+
+app = FastAPI()
+
+
+class APIRouteA(APIRoute):
+    x_type = "A"
+
+
+class APIRouteB(APIRoute):
+    x_type = "B"
+
+
+class APIRouteC(APIRoute):
+    x_type = "C"
+
+
+router_a = APIRouter(route_class=APIRouteA)
+router_b = APIRouter(route_class=APIRouteB)
+router_c = APIRouter(route_class=APIRouteC)
+
+
+@router_a.get("/")
+def get_a():
+    return {"msg": "A"}
+
+
+@router_b.get("/")
+def get_b():
+    return {"msg": "B"}
+
+
+@router_c.get("/")
+def get_c():
+    return {"msg": "C"}
+
+
+router_b.include_router(router=router_c, prefix="/c")
+router_a.include_router(router=router_b, prefix="/b")
+app.include_router(router=router_a, prefix="/a")
+
+
+client = TestClient(app)
+
+openapi_schema = {
+    "openapi": "3.0.2",
+    "info": {"title": "Fast API", "version": "0.1.0"},
+    "paths": {
+        "/a/": {
+            "get": {
+                "responses": {
+                    "200": {
+                        "description": "Successful Response",
+                        "content": {"application/json": {"schema": {}}},
+                    }
+                },
+                "summary": "Get A",
+                "operationId": "get_a_a__get",
+            }
+        },
+        "/a/b/": {
+            "get": {
+                "responses": {
+                    "200": {
+                        "description": "Successful Response",
+                        "content": {"application/json": {"schema": {}}},
+                    }
+                },
+                "summary": "Get B",
+                "operationId": "get_b_a_b__get",
+            }
+        },
+        "/a/b/c/": {
+            "get": {
+                "responses": {
+                    "200": {
+                        "description": "Successful Response",
+                        "content": {"application/json": {"schema": {}}},
+                    }
+                },
+                "summary": "Get C",
+                "operationId": "get_c_a_b_c__get",
+            }
+        },
+    },
+}
+
+
+@pytest.mark.parametrize(
+    "path,expected_status,expected_response",
+    [
+        ("/a", 200, {"msg": "A"}),
+        ("/a/b", 200, {"msg": "B"}),
+        ("/a/b/c", 200, {"msg": "C"}),
+        ("/openapi.json", 200, openapi_schema),
+    ],
+)
+def test_get_path(path, expected_status, expected_response):
+    response = client.get(path)
+    assert response.status_code == expected_status
+    assert response.json() == expected_response
+
+
+def test_route_classes():
+    routes = {}
+    r: APIRoute
+    for r in app.router.routes:
+        routes[r.path] = r
+    assert routes["/a/"].x_type == "A"
+    assert routes["/a/b/"].x_type == "B"
+    assert routes["/a/b/c/"].x_type == "C"

tests/test_tutorial/test_custom_request_and_route/test_tutorial001.py

@@ -0,0 +1,34 @@
+import gzip
+import json
+
+import pytest
+from starlette.requests import Request
+from starlette.testclient import TestClient
+
+from custom_request_and_route.tutorial001 import app
+
+
+@app.get("/check-class")
+async def check_gzip_request(request: Request):
+    return {"request_class": type(request).__name__}
+
+
+client = TestClient(app)
+
+
+@pytest.mark.parametrize("compress", [True, False])
+def test_gzip_request(compress):
+    n = 1000
+    headers = {}
+    body = [1] * n
+    data = json.dumps(body).encode()
+    if compress:
+        data = gzip.compress(data)
+        headers["Content-Encoding"] = "gzip"
+    response = client.post("/sum", data=data, headers=headers)
+    assert response.json() == {"sum": n}
+
+
+def test_request_class():
+    response = client.get("/check-class")
+    assert response.json() == {"request_class": "GzipRequest"}

tests/test_tutorial/test_custom_request_and_route/test_tutorial002.py

@@ -0,0 +1,27 @@
+from starlette.testclient import TestClient
+
+from custom_request_and_route.tutorial002 import app
+
+client = TestClient(app)
+
+
+def test_endpoint_works():
+    response = client.post("/", json=[1, 2, 3])
+    assert response.json() == 6
+
+
+def test_exception_handler_body_access():
+    response = client.post("/", json={"numbers": [1, 2, 3]})
+
+    assert response.json() == {
+        "detail": {
+            "body": '{"numbers": [1, 2, 3]}',
+            "errors": [
+                {
+                    "loc": ["body", "numbers"],
+                    "msg": "value is not a valid list",
+                    "type": "type_error.list",
+                }
+            ],
+        }
+    }

tests/test_tutorial/test_custom_request_and_route/test_tutorial003.py

@@ -0,0 +1,18 @@
+from starlette.testclient import TestClient
+
+from custom_request_and_route.tutorial003 import app
+
+client = TestClient(app)
+
+
+def test_get():
+    response = client.get("/")
+    assert response.json() == {"message": "Not timed"}
+    assert "X-Response-Time" not in response.headers
+
+
+def test_get_timed():
+    response = client.get("/timed")
+    assert response.json() == {"message": "It's the time of my life"}
+    assert "X-Response-Time" in response.headers
+    assert float(response.headers["X-Response-Time"]) > 0