请求体 - 多个参数¶

既然我们已经知道了如何使用 Path 和 Query，下面让我们来了解一下请求体声明的更高级用法。

混合使用 `Path`、`Query` 和请求体参数¶

首先，毫无疑问地，你可以随意地混合使用 Path、Query 和请求体参数声明，FastAPI 会知道该如何处理。

你还可以通过将默认值设置为 None 来将请求体参数声明为可选参数：

Python 3.10+

from typing import Annotated

from fastapi import FastAPI, Path
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: Annotated[int, Path(title="The ID of the item to get", ge=0, le=1000)],
    q: str | None = None,
    item: Item | None = None,
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})
    if item:
        results.update({"item": item})
    return results

🤓 Other versions and variants

Python 3.9+Python 3.8+Python 3.10+ - non-AnnotatedPython 3.8+ - non-Annotated

from typing import Annotated, Union

from fastapi import FastAPI, Path
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: Annotated[int, Path(title="The ID of the item to get", ge=0, le=1000)],
    q: Union[str, None] = None,
    item: Union[Item, None] = None,
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})
    if item:
        results.update({"item": item})
    return results

from typing import Union

from fastapi import FastAPI, Path
from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: Annotated[int, Path(title="The ID of the item to get", ge=0, le=1000)],
    q: Union[str, None] = None,
    item: Union[Item, None] = None,
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})
    if item:
        results.update({"item": item})
    return results

Tip

Prefer to use the Annotated version if possible.

from fastapi import FastAPI, Path
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int = Path(title="The ID of the item to get", ge=0, le=1000),
    q: str | None = None,
    item: Item | None = None,
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})
    if item:
        results.update({"item": item})
    return results

Tip

Prefer to use the Annotated version if possible.

from typing import Union

from fastapi import FastAPI, Path
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int = Path(title="The ID of the item to get", ge=0, le=1000),
    q: Union[str, None] = None,
    item: Union[Item, None] = None,
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})
    if item:
        results.update({"item": item})
    return results

Note

请注意，在这种情况下，将从请求体获取的 item 是可选的。因为它的默认值为 None。

多个请求体参数¶

在上面的示例中，路径操作将期望一个具有 Item 的属性的 JSON 请求体，就像：

{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2
}

但是你也可以声明多个请求体参数，例如 item 和 user：

Python 3.10+

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


class User(BaseModel):
    username: str
    full_name: str | None = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item, user: User):
    results = {"item_id": item_id, "item": item, "user": user}
    return results

🤓 Other versions and variants

Python 3.8+

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item, user: User):
    results = {"item_id": item_id, "item": item, "user": user}
    return results

在这种情况下，FastAPI 将注意到该函数中有多个请求体参数（两个 Pydantic 模型参数）。

因此，它将使用参数名称作为请求体中的键（字段名称），并期望一个类似于以下内容的请求体：

{
    "item": {
        "name": "Foo",
        "description": "The pretender",
        "price": 42.0,
        "tax": 3.2
    },
    "user": {
        "username": "dave",
        "full_name": "Dave Grohl"
    }
}

Note

请注意，即使 item 的声明方式与之前相同，但现在它被期望通过 item 键内嵌在请求体中。

FastAPI 将自动对请求中的数据进行转换，因此 item 参数将接收指定的内容，user 参数也是如此。

它将执行对复合数据的校验，并且像现在这样为 OpenAPI 模式和自动化文档对其进行记录。

请求体中的单一值¶

与使用 Query 和 Path 为查询参数和路径参数定义额外数据的方式相同，FastAPI 提供了一个同等的 Body。

例如，为了扩展先前的模型，你可能决定除了 item 和 user 之外，还想在同一请求体中具有另一个键 importance。

如果你就按原样声明它，因为它是一个单一值，FastAPI 将假定它是一个查询参数。

但是你可以使用 Body 指示 FastAPI 将其作为请求体的另一个键进行处理。

Python 3.10+

from typing import Annotated

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


class User(BaseModel):
    username: str
    full_name: str | None = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: int, item: Item, user: User, importance: Annotated[int, Body()]
):
    results = {"item_id": item_id, "item": item, "user": user, "importance": importance}
    return results

🤓 Other versions and variants

Python 3.9+Python 3.8+Python 3.10+ - non-AnnotatedPython 3.8+ - non-Annotated

from typing import Annotated, Union

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: int, item: Item, user: User, importance: Annotated[int, Body()]
):
    results = {"item_id": item_id, "item": item, "user": user, "importance": importance}
    return results

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: int, item: Item, user: User, importance: Annotated[int, Body()]
):
    results = {"item_id": item_id, "item": item, "user": user, "importance": importance}
    return results

Tip

Prefer to use the Annotated version if possible.

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


class User(BaseModel):
    username: str
    full_name: str | None = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item, user: User, importance: int = Body()):
    results = {"item_id": item_id, "item": item, "user": user, "importance": importance}
    return results

Tip

Prefer to use the Annotated version if possible.

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item, user: User, importance: int = Body()):
    results = {"item_id": item_id, "item": item, "user": user, "importance": importance}
    return results

在这种情况下，FastAPI 将期望像这样的请求体：

{
    "item": {
        "name": "Foo",
        "description": "The pretender",
        "price": 42.0,
        "tax": 3.2
    },
    "user": {
        "username": "dave",
        "full_name": "Dave Grohl"
    },
    "importance": 5
}

同样的，它将转换数据类型，校验，生成文档等。

多个请求体参数和查询参数¶

当然，除了请求体参数外，你还可以在任何需要的时候声明额外的查询参数。

由于默认情况下单一值被解释为查询参数，因此你不必显式地添加 Query，你可以仅执行以下操作：

q: str = None

比如：

Python 3.10+

from typing import Annotated

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


class User(BaseModel):
    username: str
    full_name: str | None = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Item,
    user: User,
    importance: Annotated[int, Body(gt=0)],
    q: str | None = None,
):
    results = {"item_id": item_id, "item": item, "user": user, "importance": importance}
    if q:
        results.update({"q": q})
    return results

🤓 Other versions and variants

Python 3.9+Python 3.8+Python 3.10+ - non-AnnotatedPython 3.8+ - non-Annotated

from typing import Annotated, Union

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Item,
    user: User,
    importance: Annotated[int, Body(gt=0)],
    q: Union[str, None] = None,
):
    results = {"item_id": item_id, "item": item, "user": user, "importance": importance}
    if q:
        results.update({"q": q})
    return results

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Item,
    user: User,
    importance: Annotated[int, Body(gt=0)],
    q: Union[str, None] = None,
):
    results = {"item_id": item_id, "item": item, "user": user, "importance": importance}
    if q:
        results.update({"q": q})
    return results

Tip

Prefer to use the Annotated version if possible.

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


class User(BaseModel):
    username: str
    full_name: str | None = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Item,
    user: User,
    importance: int = Body(gt=0),
    q: str | None = None,
):
    results = {"item_id": item_id, "item": item, "user": user, "importance": importance}
    if q:
        results.update({"q": q})
    return results

Tip

Prefer to use the Annotated version if possible.

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


class User(BaseModel):
    username: str
    full_name: Union[str, None] = None


@app.put("/items/{item_id}")
async def update_item(
    *,
    item_id: int,
    item: Item,
    user: User,
    importance: int = Body(gt=0),
    q: Union[str, None] = None,
):
    results = {"item_id": item_id, "item": item, "user": user, "importance": importance}
    if q:
        results.update({"q": q})
    return results

Info

Body 同样具有与 Query、Path 以及其他后面将看到的类完全相同的额外校验和元数据参数。

嵌入单个请求体参数¶

假设你只有一个来自 Pydantic 模型 Item 的请求体参数 item。

默认情况下，FastAPI 将直接期望这样的请求体。

但是，如果你希望它期望一个拥有 item 键并在值中包含模型内容的 JSON，就像在声明额外的请求体参数时所做的那样，则可以使用一个特殊的 Body 参数 embed：

item: Item = Body(embed=True)

比如：

Python 3.10+

from typing import Annotated

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Annotated[Item, Body(embed=True)]):
    results = {"item_id": item_id, "item": item}
    return results

🤓 Other versions and variants

Python 3.9+Python 3.8+Python 3.10+ - non-AnnotatedPython 3.8+ - non-Annotated

from typing import Annotated, Union

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Annotated[Item, Body(embed=True)]):
    results = {"item_id": item_id, "item": item}
    return results

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Annotated[Item, Body(embed=True)]):
    results = {"item_id": item_id, "item": item}
    return results

Tip

Prefer to use the Annotated version if possible.

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item = Body(embed=True)):
    results = {"item_id": item_id, "item": item}
    return results

Tip

Prefer to use the Annotated version if possible.

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item = Body(embed=True)):
    results = {"item_id": item_id, "item": item}
    return results

在这种情况下，FastAPI 将期望像这样的请求体：

{
    "item": {
        "name": "Foo",
        "description": "The pretender",
        "price": 42.0,
        "tax": 3.2
    }
}

而不是：

{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2
}

总结¶

你可以添加多个请求体参数到路径操作函数中，即使一个请求只能有一个请求体。

但是 FastAPI 会处理它，在函数中为你提供正确的数据，并在路径操作中校验并记录正确的模式。

你还可以声明将作为请求体的一部分所接收的单一值。

你还可以指示 FastAPI 在仅声明了一个请求体参数的情况下，将原本的请求体嵌入到一个键中。

请求体 - 多个参数¶

混合使用 Path、Query 和请求体参数¶

多个请求体参数¶

请求体中的单一值¶

多个请求体参数和查询参数¶

嵌入单个请求体参数¶

总结¶

混合使用 `Path`、`Query` 和请求体参数¶