路径操作装饰器中的依赖项¶

在某些情况下，您并不真正需要在路径操作函数内部使用依赖项的返回值。

或者依赖项不返回任何值。

但您仍然需要执行/解析它。

对于这些情况，您不必使用 Depends 声明路径操作函数参数，而是可以向路径操作装饰器添加一个 dependencies 的 list。

向路径操作装饰器添加 `dependencies`¶

路径操作装饰器接收一个可选参数 dependencies。

它应该是一个由 Depends() 组成的 list：

Python 3.9+

from typing import Annotated

from fastapi import Depends, FastAPI, Header, HTTPException

app = FastAPI()


async def verify_token(x_token: Annotated[str, Header()]):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: Annotated[str, Header()]):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

🤓 Other versions and variants

Python 3.8+Python 3.8+ - non-Annotated

from fastapi import Depends, FastAPI, Header, HTTPException
from typing_extensions import Annotated

app = FastAPI()


async def verify_token(x_token: Annotated[str, Header()]):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: Annotated[str, Header()]):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

Tip

Prefer to use the Annotated version if possible.

from fastapi import Depends, FastAPI, Header, HTTPException

app = FastAPI()


async def verify_token(x_token: str = Header()):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: str = Header()):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

这些依赖项将以与普通依赖项相同的方式执行/解析。但它们的值（如果它们返回任何值）不会传递给您的路径操作函数。

Tip

一些编辑器会检查未使用的函数参数，并将其显示为错误。

在路径操作装饰器中使用这些 dependencies，您可以确保它们被执行，同时避免编辑器/工具错误。

它还可以帮助避免新开发人员的困惑，他们看到代码中未使用的参数，可能会认为这是不必要的。

Info

在这个例子中，我们使用了自定义的头部 X-Key 和 X-Token。

但在实际情况下，当实现安全性时，使用集成的安全工具（下一章）会带来更多好处。

依赖项错误和返回值¶

您可以使用与通常相同的依赖函数。

依赖项要求¶

它们可以声明请求要求（如头部）或其他子依赖项：

Python 3.9+

from typing import Annotated

from fastapi import Depends, FastAPI, Header, HTTPException

app = FastAPI()


async def verify_token(x_token: Annotated[str, Header()]):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: Annotated[str, Header()]):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

🤓 Other versions and variants

Python 3.8+Python 3.8+ - non-Annotated

from fastapi import Depends, FastAPI, Header, HTTPException
from typing_extensions import Annotated

app = FastAPI()


async def verify_token(x_token: Annotated[str, Header()]):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: Annotated[str, Header()]):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

Tip

Prefer to use the Annotated version if possible.

from fastapi import Depends, FastAPI, Header, HTTPException

app = FastAPI()


async def verify_token(x_token: str = Header()):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: str = Header()):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

抛出异常¶

这些依赖项可以 raise 异常，与普通依赖项相同：

Python 3.9+

from typing import Annotated

from fastapi import Depends, FastAPI, Header, HTTPException

app = FastAPI()


async def verify_token(x_token: Annotated[str, Header()]):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: Annotated[str, Header()]):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

🤓 Other versions and variants

Python 3.8+Python 3.8+ - non-Annotated

from fastapi import Depends, FastAPI, Header, HTTPException
from typing_extensions import Annotated

app = FastAPI()


async def verify_token(x_token: Annotated[str, Header()]):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: Annotated[str, Header()]):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

Tip

Prefer to use the Annotated version if possible.

from fastapi import Depends, FastAPI, Header, HTTPException

app = FastAPI()


async def verify_token(x_token: str = Header()):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: str = Header()):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

返回值¶

它们可以返回值或不返回值，这些值不会被使用。

因此，您可以重用已经在其他地方使用的普通依赖项（返回值），即使该值不会被使用，依赖项也会被执行：

Python 3.9+

from typing import Annotated

from fastapi import Depends, FastAPI, Header, HTTPException

app = FastAPI()


async def verify_token(x_token: Annotated[str, Header()]):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: Annotated[str, Header()]):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

🤓 Other versions and variants

Python 3.8+Python 3.8+ - non-Annotated

from fastapi import Depends, FastAPI, Header, HTTPException
from typing_extensions import Annotated

app = FastAPI()


async def verify_token(x_token: Annotated[str, Header()]):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: Annotated[str, Header()]):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

Tip

Prefer to use the Annotated version if possible.

from fastapi import Depends, FastAPI, Header, HTTPException

app = FastAPI()


async def verify_token(x_token: str = Header()):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: str = Header()):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

用于一组路径操作的依赖项¶

稍后，在阅读关于如何构建更大应用程序（更大的应用程序 - 多文件），可能涉及多个文件时，您将学习如何为一组路径操作声明单个 dependencies 参数。

全局依赖项¶

接下来，我们将看到如何向整个 FastAPI 应用程序添加依赖项，以便它们应用于每个路径操作。

路径操作装饰器中的依赖项¶

向路径操作装饰器添加 dependencies¶

依赖项错误和返回值¶

依赖项要求¶

抛出异常¶

返回值¶

用于一组路径操作的依赖项¶

全局依赖项¶

向路径操作装饰器添加 `dependencies`¶