✨ Add reference (code API) docs with PEP 727, add subclass with custom docstrings for BackgroundTasks, refactor docs structure (#10392)

* ➕ Add mkdocstrings and griffe-typingdoc to dependencies

* 🔧 Add mkdocstrings configs to MkDocs

* 📝 Add first WIP reference page

* ⬆️ Upgrade typing-extensions to the minimum version including Doc()

* 📝 Add docs to FastAPI parameters

* 📝 Add docstrings for OpenAPI docs utils

* 📝 Add docstrings for security utils

* 📝 Add docstrings for UploadFile

* 📝 Update docstrings in FastAPI class

* 📝 Add docstrings for path operation methods

* 📝 Add docstring for jsonable_encoder

* 📝 Add docstrings for exceptions

* 📝 Add docstsrings for parameter functions

* 📝 Add docstrings for responses

* 📝 Add docstrings for APIRouter

* ♻️ Sub-class BackgroundTasks to document it with docstrings

* 📝 Update usage of background tasks in dependencies

* ✅ Update tests with new deprecation warnings

* 📝 Add new reference docs

* 🔧 Update MkDocs with new reference docs

* ✅ Update pytest fixture, deprecation is raised only once

* 🎨 Update format for types in exceptions.py

* ♻️ Update annotations in BackgroundTask, `Annotated` can't take ParamSpec's P.args or P.kwargs

* ✏️ Fix typos caught by @pawamoy

* 🔧 Update and fix MkDocstrings configs from @pawamoy tips

* 📝 Update reference docs

* ✏️ Fix typos found by @pawamoy

* ➕ Add HTTPX as a dependency for docs, for the TestClient

* 🔧 Update MkDocs config, rename websockets reference

* 🔇 Add type-ignores for Doc as the stubs haven't been released for mypy

* 🔥 Remove duplicated deprecated notice

* 🔇 Remove typing error for unreleased stub in openapi/docs.py

* ✅ Add tests for UploadFile for coverage

* ⬆️ Upgrade griffe-typingdoc==0.2.2

* 📝 Refactor docs structure

* 🔨 Update README generation with new index frontmatter and style

* 🔨 Update generation of languages, remove from top menu, keep in lang menu

* 📝 Add OpenAPI Pydantic models

* 🔨 Update docs script to not translate Reference and Release Notes

* 🔧 Add reference for OpenAPI models

* 🔧 Update MkDocs config for mkdocstrings insiders

* 👷 Install mkdocstring insiders in CI for docs

* 🐛 Fix MkDocstrings insiders install URL

* ➕ Move dependencies shared by docs and tests to its own requirements file

* 👷 Update cache keys for test and docs dependencies

* 📝 Remove no longer needed __init__ placeholder docstrings

* 📝 Move docstring for APIRouter to the class level (not __init__ level)

* 🔥 Remove no longer needed dummy placeholder __init__ docstring

fastapi/datastructures.py

@@ -1,4 +1,14 @@
-from typing import Any, Callable, Dict, Iterable, Type, TypeVar, cast
+from typing import (
+    Any,
+    BinaryIO,
+    Callable,
+    Dict,
+    Iterable,
+    Optional,
+    Type,
+    TypeVar,
+    cast,
+)
 
 from fastapi._compat import (
     PYDANTIC_V2,
@@ -14,9 +24,120 @@ from starlette.datastructures import Headers as Headers  # noqa: F401
 from starlette.datastructures import QueryParams as QueryParams  # noqa: F401
 from starlette.datastructures import State as State  # noqa: F401
 from starlette.datastructures import UploadFile as StarletteUploadFile
+from typing_extensions import Annotated, Doc  # type: ignore [attr-defined]
 
 
 class UploadFile(StarletteUploadFile):
+    """
+    A file uploaded in a request.
+
+    Define it as a *path operation function* (or dependency) parameter.
+
+    If you are using a regular `def` function, you can use the `upload_file.file`
+    attribute to access the raw standard Python file (blocking, not async), useful and
+    needed for non-async code.
+
+    Read more about it in the
+    [FastAPI docs for Request Files](https://fastapi.tiangolo.com/tutorial/request-files/).
+
+    ## Example
+
+    ```python
+    from typing import Annotated
+
+    from fastapi import FastAPI, File, UploadFile
+
+    app = FastAPI()
+
+
+    @app.post("/files/")
+    async def create_file(file: Annotated[bytes, File()]):
+        return {"file_size": len(file)}
+
+
+    @app.post("/uploadfile/")
+    async def create_upload_file(file: UploadFile):
+        return {"filename": file.filename}
+    ```
+    """
+
+    file: Annotated[
+        BinaryIO,
+        Doc("The standard Python file object (non-async)."),
+    ]
+    filename: Annotated[Optional[str], Doc("The original file name.")]
+    size: Annotated[Optional[int], Doc("The size of the file in bytes.")]
+    headers: Annotated[Headers, Doc("The headers of the request.")]
+    content_type: Annotated[
+        Optional[str], Doc("The content type of the request, from the headers.")
+    ]
+
+    async def write(
+        self,
+        data: Annotated[
+            bytes,
+            Doc(
+                """
+                The bytes to write to the file.
+                """
+            ),
+        ],
+    ) -> None:
+        """
+        Write some bytes to the file.
+
+        You normally wouldn't use this from a file you read in a request.
+
+        To be awaitable, compatible with async, this is run in threadpool.
+        """
+        return await super().write(data)
+
+    async def read(
+        self,
+        size: Annotated[
+            int,
+            Doc(
+                """
+                The number of bytes to read from the file.
+                """
+            ),
+        ] = -1,
+    ) -> bytes:
+        """
+        Read some bytes from the file.
+
+        To be awaitable, compatible with async, this is run in threadpool.
+        """
+        return await super().read(size)
+
+    async def seek(
+        self,
+        offset: Annotated[
+            int,
+            Doc(
+                """
+                The position in bytes to seek to in the file.
+                """
+            ),
+        ],
+    ) -> None:
+        """
+        Move to a position in the file.
+
+        Any next read or write will be done from that position.
+
+        To be awaitable, compatible with async, this is run in threadpool.
+        """
+        return await super().seek(offset)
+
+    async def close(self) -> None:
+        """
+        Close the file.
+
+        To be awaitable, compatible with async, this is run in threadpool.
+        """
+        return await super().close()
+
     @classmethod
     def __get_validators__(cls: Type["UploadFile"]) -> Iterable[Callable[..., Any]]:
         yield cls.validate