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)):

    Check the docs about <a href="https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/about-pull-request-reviews" class="external-link" target="_blank">adding a pull request review</a> to approve it or request changes.

```Python hl_lines="7"
{!../../../docs_src/path_params/tutorial002.py!}
```

In this case, `item_id` is declared to be an `int`.

!!! check
    This will give you editor support inside of your function, with error checks, completion, etc.

## Data <abbr title="also known as: serialization, parsing, marshalling">conversion</abbr>

But when checking benchmarks and comparisons you should keep the following in mind.

## Benchmarks and speed

When you check the benchmarks, it is common to see several tools of different types compared as equivalent.

import re
import warnings
from dataclasses import is_dataclass
from typing import (
    TYPE_CHECKING,
    Any,
    Dict,
    MutableMapping,
    Optional,
    Set,
    Type,
    Union,
    cast,
)
from weakref import WeakKeyDictionary

import fastapi
from fastapi._compat import (
    PYDANTIC_V2,
    BaseConfig,
    ModelField,
    PydanticSchemaGenerationError,
    Undefined,
    UndefinedType,

These features are what Marshmallow was built to provide. It is a great library, and I have used it a lot before.

But it was created before there existed Python type hints. So, to define every <abbr title="the definition of how data should be formed">schema</abbr> you need to use specific utils and classes provided by Marshmallow.

!!! check "Inspired **FastAPI** to"

In the previous example, because the classes were different, we had to use the `response_model` parameter. But that also means that we don't get the support from the editor and tools checking the function return type.

But in most of the cases where we need to do something like this, we want the model just to **filter/remove** some of the data as in this example.

### Check the docs UI

But here's the fun part. ✨

The "official" way to access the app would be through the proxy with the path prefix that we defined. So, as we would expect, if you try the docs UI served by Uvicorn directly, without the path prefix in the URL, it won't work, because it expects to be accessed through the proxy.

```Python hl_lines="16"
{!../../../docs_src/dependencies/tutorial011.py!}
```

这样就可以**参数化**依赖项，它包含 `checker.fixed_content` 的属性 - `"bar"`。

## 把实例作为依赖项

然后，不要再在 `Depends(checker)` 中使用 `Depends(FixedContentQueryChecker)`， 而是要使用 `checker`，因为依赖项是类实例 - `checker`，不是类。

处理依赖项时，**FastAPI** 以如下方式调用 `checker`：

```Python
checker(q="somequery")
```

……并用*路径操作函数*的参数 `fixed_content_included` 返回依赖项的值：

```Python hl_lines="20"

{!../../../docs_src/dependencies/tutorial011.py!}
```

& 👈 🌌 👥 💪 "🔗" 👆 🔗, 👈 🔜 ✔️ `"bar"` 🔘 ⚫️, 🔢 `checker.fixed_content`.

## ⚙️ 👐 🔗

⤴️, 👥 💪 ⚙️ 👉 `checker` `Depends(checker)`, ↩️ `Depends(FixedContentQueryChecker)`, ↩️ 🔗 👐, `checker`, 🚫 🎓 ⚫️.

& 🕐❔ ❎ 🔗, **FastAPI** 🔜 🤙 👉 `checker` 💖:

```Python
checker(q="somequery")
```

...& 🚶‍♀️ ⚫️❔ 👈 📨 💲 🔗 👆 *➡ 🛠️ 🔢* 🔢 `fixed_content_included`: