def __call__(self, q: str = ""):
        if q:
            return self.fixed_content in q
        return False


checker = FixedContentQueryChecker("bar")


@app.get("/query-checker/")
async def read_query_check(fixed_content_included: bool = Depends(checker)):

    q: Annotated[str, Depends(query_extractor)],
    last_query: Annotated[Union[str, None], Cookie()] = None,
):
    if not q:
        return last_query
    return q


@app.get("/items/")
async def read_query(
    query_or_default: Annotated[str, Depends(query_or_cookie_extractor)],
):

    q: Annotated[str, Depends(query_extractor)],
    last_query: Annotated[Union[str, None], Cookie()] = None,
):
    if not q:
        return last_query
    return q


@app.get("/items/")
async def read_query(
    query_or_default: Annotated[str, Depends(query_or_cookie_extractor)],
):

    q: Annotated[str, Depends(query_extractor)],
    last_query: Annotated[str | None, Cookie()] = None,
):
    if not q:
        return last_query
    return q


@app.get("/items/")
async def read_query(
    query_or_default: Annotated[str, Depends(query_or_cookie_extractor)],
):

    def __call__(self, q: str = ""):
        if q:
            return self.fixed_content in q
        return False


checker = FixedContentQueryChecker("bar")


@app.get("/query-checker/")
async def read_query_check(fixed_content_included: Annotated[bool, Depends(checker)]):

```mermaid
graph TB

query_extractor(["query_extractor"])
query_or_cookie_extractor(["query_or_cookie_extractor"])

read_query["/items/"]

query_extractor --> query_or_cookie_extractor --> read_query
```

## 多次使用同一个依赖项

如果在同一个*路径操作* 多次声明了同一个依赖项，例如，多个依赖项共用一个子依赖项，**FastAPI** 在处理同一请求时，只调用一次该子依赖项。

    q: str = Depends(query_extractor),
    last_query: Union[str, None] = Cookie(default=None),
):
    if not q:
        return last_query
    return q


@app.get("/items/")
async def read_query(query_or_default: str = Depends(query_or_cookie_extractor)):

def query_or_cookie_extractor(
    q: str = Depends(query_extractor), last_query: str | None = Cookie(default=None)
):
    if not q:
        return last_query
    return q


@app.get("/items/")
async def read_query(query_or_default: str = Depends(query_or_cookie_extractor)):

    def __call__(self, q: str = ""):
        if q:
            return self.fixed_content in q
        return False


checker = FixedContentQueryChecker("bar")


@app.get("/query-checker/")
async def read_query_check(fixed_content_included: Annotated[bool, Depends(checker)]):

```mermaid
graph TB

query_extractor(["query_extractor"])
query_or_cookie_extractor(["query_or_cookie_extractor"])

read_query["/items/"]

query_extractor --> query_or_cookie_extractor --> read_query
```

## Dieselbe Abhängigkeit mehrmals verwenden