/// 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] *}

    size: Annotated[int | None, Body()] = None,
):
    if item_id in items:
        item = items[item_id]
        item["name"] = name
        item["size"] = size
        return item
    else:
        item = {"name": name, "size": size}
        items[item_id] = item

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}

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()]
):

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

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}

            "/items/{item_id}": {
                "put": {
                    "summary": "Update Item",
                    "operationId": "update_item_items__item_id__put",
                    "parameters": [
                        {
                            "required": True,
                            "schema": {"title": "Item Id", "type": "integer"},
                            "name": "item_id",

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)],

    public void init() throws IOException {
        /*
         * TODO if (initialized) { return; }
         *
         * if (tokenizerFactory == null) { final String path = System.getProperty(SuggestConstants.USER_DICT_PATH);
         * final String encoding = System.getProperty(SuggestConstants.USER_DICT_ENCODING); final Map<String, String>
         * args = new HashMap<>(); args.put("mode", "normal"); args.put("discardPunctuation", "false"); if