client = TestClient(app)


def test_path_operation():
    response = client.get("/items/foo")
    assert response.status_code == 200, response.text
    assert response.json() == {"id": "foo", "value": "there goes my hero"}


def test_path_operation_not_found():
    response = client.get("/items/bar")
    assert response.status_code == 404, response.text
    assert response.json() == {"message": "Item not found"}

from fastapi import FastAPI

app = FastAPI()


@app.get("/items/", tags=["items"])
async def read_items():
    return [{"name": "Foo", "price": 42}]


@app.get("/users/", tags=["users"])
async def read_users():
    return [{"username": "johndoe"}]


@app.get("/elements/", tags=["items"], deprecated=True)
async def read_elements():

이 예제를 실행하고 [http://127.0.0.1:8000/items/3](http://127.0.0.1:8000/items/3)을 열면, 다음 응답을 볼 수 있습니다:

```JSON
{"item_id":3}
```

/// check | 확인

함수가 받은(반환도 하는) 값은 문자열 `"3"`이 아니라 파이썬 `int` 형인 `3`입니다.

즉, 타입 선언을 하면 **FastAPI**는 자동으로 요청을 <dfn title="HTTP 요청에서 전달되는 문자열을 파이썬 데이터로 변환">"파싱"</dfn>합니다.

///

## 데이터 검증 { #data-validation }

Und wenn Sie den Scope `me`, aber nicht den Scope `items` auswählen, können Sie auf `/users/me/` zugreifen, aber nicht auf `/users/me/items/`.

O valor do parâmetro de path `item_id` será passado para a sua função como o argumento `item_id`.

Então, se você executar este exemplo e acessar [http://127.0.0.1:8000/items/foo](http://127.0.0.1:8000/items/foo), você verá uma resposta:

```JSON
{"item_id":"foo"}
```

## Parâmetros de path com tipos { #path-parameters-with-types }

运行示例并访问 [http://127.0.0.1:8000/items/3](http://127.0.0.1:8000/items/3)，返回的响应如下：

```JSON
{"item_id":3}
```

/// check | 检查

注意，函数接收并返回的值是 `3`（ `int`），不是 `"3"`（`str`）。

**FastAPI** 通过类型声明自动进行请求的<dfn title="将来自 HTTP 请求中的字符串转换为 Python 数据类型">解析</dfn>。

///

## 数据校验 { #data-validation }

通过浏览器访问 [http://127.0.0.1:8000/items/foo](http://127.0.0.1:8000/items/foo)，接收如下 HTTP 错误信息：

```JSON
{

        return OptionalEntity.empty();
    }

    /**
     * Retrieves a paginated list of character mapping items.
     *
     * @param offset the starting index for pagination (0-based)
     * @param size the maximum number of items to return
     * @return a PagingList containing the requested subset of mapping items
     */
    @Override

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: str | None = Query(min_length=3)):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: str = Query(default="fixedquery", min_length=3)):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        str | None,
        Query(
            title="Query string",
            description="Query string for the items to search in the database that have a good match",
            min_length=3,
        ),
    ] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q: