Pydantic によって、標準的な Python の型を使ってボディを宣言します。

```Python hl_lines="2  7-10 23-25"
from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: bool | None = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: str | None = None):

```Python hl_lines="2  7-10 23-25"
from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: bool | None = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: str | None = None):

多虧了 Pydantic，你可以用標準的 Python 型別來宣告 body。

```Python hl_lines="2  7-10 23-25"
from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: bool | None = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: str | None = None):

 *
 * <p>This class should not be assumed to be universally superior to {@code
 * java.util.LinkedHashMap}. Generally speaking, this class reduces object allocation and memory
 * consumption at the price of moderately increased constant factors of CPU. Only use this class
 * when there is a specific reason to prioritize memory over CPU.
 *
 * @author Louis Wasserman
 */

Dans ce cas, vous pouvez désactiver cette fonctionnalité dans **FastAPI**, avec le paramètre `separate_input_output_schemas=False`.

/// info | info

La prise en charge de `separate_input_output_schemas` a été ajoutée dans FastAPI `0.102.0`. 🤓

///

{* ../../docs_src/separate_openapi_schemas/tutorial002_py310.py hl[10] *}

### Warning about replacing { #warning-about-replacing }

That means that if you want to update the item `bar` using `PUT` with a body containing:

```Python
{
    "name": "Barz",
    "price": 3,
    "description": None,
}
```

because it doesn't include the already stored attribute `"tax": 20.2`, the input model would take the default value of `"tax": 10.5`.

### Aviso sobre a substituição { #warning-about-replacing }

Isso significa que, se você quiser atualizar o item `bar` usando `PUT` com um corpo contendo:

```Python
{
    "name": "Barz",
    "price": 3,
    "description": None,
}
```

como ele não inclui o atributo já armazenado `"tax": 20.2`, o modelo de entrada assumiria o valor padrão de `"tax": 10.5`.

E os dados seriam salvos com esse "novo" `tax` de `10.5`.

```Python hl_lines="2  7-10 23-25"
from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: bool | None = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: str | None = None):

例えば、上記のモデルは次のようなJSON「`object`」（またはPythonの `dict`）を宣言します:

```JSON
{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5
}
```

...`description` と `tax` はオプション（デフォルト値が `None`）なので、このJSON「`object`」も有効です:

```JSON
{
    "name": "Foo",
    "price": 45.2
}
```

## パラメータとして宣言 { #declare-it-as-a-parameter }

*path operation* に追加するには、パスパラメータやクエリパラメータを宣言したのと同じ方法で宣言します:

### Créer une classe `GzipRequest` personnalisée { #create-a-custom-gziprequest-class }

/// tip | Astuce

Il s'agit d'un exemple simplifié pour montrer le fonctionnement ; si vous avez besoin de la prise en charge de Gzip, vous pouvez utiliser le [`GzipMiddleware`](../advanced/middleware.md#gzipmiddleware) fourni.

///