/// 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`：

```Python
item: Item = Body(embed=True)
```

比如：

{* ../../docs_src/body_multiple_params/tutorial005_an_py310.py hl[17] *}

class Image(BaseModel):
    url: HttpUrl
    name: str


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
    tags: set[str] = set()
    image: Image | None = None


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

     * Retrieves a specific character mapping item by its ID from the specified dictionary.
     * <p>
     * This method looks up a character mapping item using its unique identifier
     * within the context of the specified dictionary.
     * </p>
     *
     * @param dictId the dictionary ID containing the character mapping item
     * @param id the unique identifier of the character mapping item

from fastapi import FastAPI
from pydantic import BaseModel


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


app = FastAPI()


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

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = Field(
        default=None, title="The description of the item", max_length=300
    )
    price: float = Field(gt=0, description="The price must be greater than zero")
    tax: float | None = None


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

    }

    /**
     * Checks whether this mapping item has pending updates.
     *
     * @return true if both newInputs and newOutput are not null, indicating pending updates
     */
    public boolean isUpdated() {
        return newInputs != null && newOutput != null;
    }

    /**
     * Checks whether this mapping item is marked for deletion.

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}

from fastapi.responses import JSONResponse
from pydantic import BaseModel


class Item(BaseModel):
    title: str
    timestamp: datetime
    description: str | None = None


app = FastAPI()


@app.put("/items/{id}")
def update_item(id: str, item: Item):
    json_compatible_item_data = jsonable_encoder(item)

    url: HttpUrl
    name: str


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


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

									<c:forEach var="item" varStatus="s" items="${popularWords}">
										<c:if test="${s.index < 3}">
											<la:link
												href="/search?q=${f:u(item)}${fe:facetQuery()}${fe:geoQuery()}">${f:h(item)}</la:link>
										</c:if>
										<c:if test="${3 <= s.index}">
											<la:link styleClass="d-none d-sm-inline-block"