from typing import Annotated

from fastapi import FastAPI, Query

app = FastAPI()


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

from typing import Annotated

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: Annotated[str | None, Query(max_length=50)] = None):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

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

    String simple = "a,b,c,d";
    Iterable<String> items = COMMA_SPLITTER.limit(1).split(simple);
    assertThat(items).containsExactly("a,b,c,d").inOrder();
  }

  public void testLimitSeparator() {
    String simple = "a,b,c,d";
    Iterable<String> items = COMMA_SPLITTER.limit(2).split(simple);
    assertThat(items).containsExactly("a", "b,c,d").inOrder();
  }

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
{

Hiç scope seçmezseniz "authenticated" olursunuz; ancak `/users/me/` veya `/users/me/items/`'e erişmeye çalıştığınızda, yeterli izniniz olmadığını söyleyen bir hata alırsınız. Yine de `/status/`'a erişebilirsiniz.

`me` scope'unu seçip `items` scope'unu seçmezseniz `/users/me/`'a erişebilirsiniz ama `/users/me/items/`'e erişemezsiniz.

            Currency.FRANC, Country.SWITZERLAND);
    EnumBiMap<Currency, Country> bimap = EnumBiMap.create(map);

    Iterator<Currency> iter = bimap.keySet().iterator();
    assertEquals(Currency.DOLLAR, iter.next());
    assertEquals(Currency.FRANC, iter.next());
    iter.remove();

    // forward map ordered by currency
    assertThat(bimap.keySet()).containsExactly(Currency.DOLLAR, Currency.PESO).inOrder();

Например, у вас есть 4 API-эндпоинта (*операции пути*):

* `/items/public/`
* `/items/private/`
* `/users/{user_id}/activate`
* `/items/pro/`

тогда вы можете добавить разные требования к правам для каждого из них только с помощью зависимостей и подзависимостей:

```mermaid
graph TB

password_hash = PasswordHash.recommended()

DUMMY_HASH = password_hash.hash("dummypassword")

oauth2_scheme = OAuth2PasswordBearer(
    tokenUrl="token",
    scopes={"me": "Read information about the current user.", "items": "Read items."},
)

app = FastAPI()


def verify_password(plain_password, hashed_password):
    return password_hash.verify(plain_password, hashed_password)


def get_password_hash(password):