```Python hl_lines="4  9-12  25-27"
from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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


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


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

```JSON
{
    "name": "Foo",
    "description": "선택적인 설명란",
    "price": 45.2,
    "tax": 3.5
}
```

...`description`과 `tax`는 (기본 값이 `None`으로 되어 있어) 선택적이기 때문에, 이 JSON "`object`"는 다음과 같은 상황에서도 유효합니다:

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

## 매개변수로서 선언하기

여러분의 *경로 작동*에 추가하기 위해, 경로 매개변수 그리고 쿼리 매개변수에서 선언했던 것과 같은 방식으로 선언하면 됩니다.

	return w, routes, nil
}

func (c *ConfigWriter) retrieveSortedRouteSlice() ([]*route.RouteConfiguration, error) {
	if c.configDump == nil {
		return nil, fmt.Errorf("config writer has not been primed")
	}
	routeDump, err := c.configDump.GetRouteConfigDump()
	if err != nil {
		return nil, err
	}
	routes := make([]*route.RouteConfiguration, 0)
	for _, r := range routeDump.DynamicRouteConfigs {

```Python hl_lines="3 5"
{
    "name": "Bar",
    "description": "The bartenders",
    "price": 62,
    "tax": 20.2
}
```

それらはレスポンスに含まれます。

#### デフォルト値と同じ値を持つデータ

ID`baz`のitemのようにデフォルト値と同じ値を持つデータの場合:

```Python hl_lines="3 5 6"
{
    "name": "Baz",
    "description": None,
    "price": 50.2,
    "tax": 10.5,
    "tags": []
}
```

```Python hl_lines="4  9-12  25-27"
from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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


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


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

```Python hl_lines="4  9-12  25-27"
from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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


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


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

<img src="/img/tutorial/generate-clients/image03.png">

/// tip | "Tipp"

Beachten Sie die automatische Vervollständigung für `name` und `price`, welche in der FastAPI-Anwendung im `Item`-Modell definiert wurden.

///

Sie erhalten Inline-Fehlerberichte für die von Ihnen gesendeten Daten:

<img src="/img/tutorial/generate-clients/image04.png">

```Python hl_lines="20"
{!> ../../docs_src/body_nested_models/tutorial004.py!}
```

////

这意味着 **FastAPI** 将期望类似于以下内容的请求体：

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2,
    "tags": ["rock", "metal", "bar"],
    "image": {
        "url": "http://example.com/baz.jpg",
        "name": "The Foo live"
    }
}
```

```Python hl_lines="2  7 8 9 10  23 24 25"
from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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


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


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

```Python hl_lines="4  9-12  25-27"
from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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


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


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