from fastapi import FastAPI, Query

app = FastAPI()


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

from typing import Union

from fastapi import FastAPI, Query
from typing_extensions import Annotated

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        Union[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,
):

    }

    public List<RelatedContent> getAvailableRelatedContentList() {
        return ComponentUtil.getComponent(RelatedContentBhv.class).selectList(cb -> {
            cb.query().matchAll();
            cb.query().addOrderBy_SortOrder_Asc();
            cb.query().addOrderBy_Term_Asc();
            cb.fetchFirst(ComponentUtil.getFessConfig().getPageRelatedcontentMaxFetchSizeAsInteger());
        });
    }

    @Override

```

////

/// note | "技术细节"

`Header` 是 `Path`、`Query`、`Cookie` 的**兄弟类**，都继承自共用的 `Param` 类。

注意，从 `fastapi` 导入的 `Query`、`Path`、`Header` 等对象，实际上是返回特殊类的函数。

///

/// info | "说明"

必须使用 `Header` 声明 header 参数，否则该参数会被解释为查询参数。

///

## 自动转换

`Header` 比 `Path`、`Query` 和 `Cookie` 提供了更多功能。

大部分标准请求头用**连字符**分隔，即**减号**（`-`）。

It includes:

* `Query()`
* `Path()`
* `Body()`
* `Cookie()`
* `Header()`
* `Form()`
* `File()`

You can import them all directly from `fastapi`:

```python
from fastapi import Body, Cookie, File, Form, Header, Path, Query
```

::: fastapi.Query

::: fastapi.Path

::: fastapi.Body

::: fastapi.Cookie

`Header` is a "sister" class of `Path`, `Query` and `Cookie`. It also inherits from the same common `Param` class.

But remember that when you import `Query`, `Path`, `Header`, and others from `fastapi`, those are actually functions that return special classes.

///

/// info

To declare headers, you need to use `Header`, because otherwise the parameters would be interpreted as query parameters.

///

        }
        load();
    }

    public List<RelatedQuery> getAvailableRelatedQueryList() {

        return ComponentUtil.getComponent(RelatedQueryBhv.class).selectList(cb -> {
            cb.query().matchAll();
            cb.query().addOrderBy_Term_Asc();
            cb.fetchFirst(ComponentUtil.getFessConfig().getPageRelatedqueryMaxFetchSizeAsInteger());
        });
    }

    @Override
    public int load() {

            ArtifactMetadata query, ArtifactRepository localRepository, List<ArtifactRepository> remoteRepositories) {
        this.query = query;
        this.localRepository = localRepository;
        this.remoteRepositories = remoteRepositories;
    }

    // --------------------------------------------------------------------
    public ArtifactMetadata getQuery() {
        return query;
    }

```

## まとめ

`Query`と`Path`（そしてまだ見たことない他のもの）では、[クエリパラメータと文字列の検証](query-params-str-validations.md){.internal-link target=_blank}と同じようにメタデータと文字列の検証を宣言することができます。

また、数値のバリデーションを宣言することもできます:

* `gt`: より大きい（`g`reater `t`han）
* `ge`: 以上（`g`reater than or `e`qual）
* `lt`: より小さい（`l`ess `t`han）
* `le`: 以下（`l`ess than or `e`qual）

/// info | "情報"

`Query`、`Path`などは後に共通の`Param`クラスのサブクラスを見ることになります。（使う必要はありません）

    if log.is_file():
        os.remove(log)  # pragma: no cover
    response = client.post("/send-notification/******@****.***?q=some-query")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Message sent"}
    with open("./log.txt") as f: