路径操作装饰器中的依赖项¶

在某些情况下，你不需要在路径操作函数内部获取依赖项的返回值。

或者该依赖项根本不返回任何值。

但你仍然需要它被执行/解决。

对于这些情况，你可以向路径操作装饰器添加一个 dependencies 列表，而不是在路径操作函数参数中声明 Depends。

向路径操作装饰器添加 `dependencies`¶

路径操作装饰器接受一个可选参数 dependencies。

它应该是一个 Depends() 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"}]

🤓 其他版本和变体

Python 3.8+Python 3.8+ - 非 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"}]

提示

如果可能，请优先使用 Annotated 版本。

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/解决。但它们的值（如果它们有返回值）不会传递给你的路径操作函数。

提示

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 可以确保它们被执行，同时避免编辑器/工具的错误。

它还有助于避免新开发人员看到代码中未使用的参数而误认为它们是不必要的。

信息

在此示例中，我们使用了虚构的自定义头 X-Key 和 X-Token。

但在实际情况中，实现安全性时，使用集成的安全工具（下一章）会获得更多好处。

依赖项的错误和返回值¶

你可以使用你通常使用的相同依赖项函数。

依赖项要求¶

它们可以声明请求要求（如请求头）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"}]

🤓 其他版本和变体

Python 3.8+Python 3.8+ - 非 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"}]

提示

如果可能，请优先使用 Annotated 版本。

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，与普通依赖项一样

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"}]

🤓 其他版本和变体

Python 3.8+Python 3.8+ - 非 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"}]

提示

如果可能，请优先使用 Annotated 版本。

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¶

它们可以返回或不返回，返回值将不会被使用。

因此，你可以重用你已经在其他地方使用的普通依赖项（它会返回一个值），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"}]

🤓 其他版本和变体

Python 3.8+Python 3.8+ - 非 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"}]

提示

如果可能，请优先使用 Annotated 版本。

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"}]

一组路径操作的依赖项¶

稍后，当你阅读关于如何构建大型应用（大型应用 - 多个文件）时，可能会涉及多个文件，你将了解到如何为一组路径操作声明一个单独的 dependencies 参数。

全局依赖项¶

接下来我们将看到如何向整个 FastAPI 应用添加依赖项，使其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¶

依赖项的错误和返回值¶

依赖项要求¶

抛出异常¶

返回值¶

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`¶