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)):

```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>

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"

    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="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`:

This will help us inside of the function with all the completion and type checks.

!!! tip
    You might remember that request bodies are also declared with Pydantic models.

    Here **FastAPI** won't get confused because you are using `Depends`.

!!! check

#!/usr/bin/env bash

set -e
set -x

mypy fastapi
ruff check fastapi tests docs_src scripts

⚫️ ⚙️ 📚 🏢 ✅ 🦎, 🟥 👒 & 🎟.

⚫️ 🕐 🥇 🖼 **🏧 🛠️ 🧾**, & 👉 🎯 🕐 🥇 💭 👈 😮 "🔎" **FastAPI**.

!!! note
    ✳ 🎂 🛠️ ✍ ✡ 🇺🇸🏛. 🎏 👼 💃 & Uvicorn, 🔛 ❔ **FastAPI** ⚓️.


!!! check "😮 **FastAPI** "
    ✔️ 🏧 🛠️ 🧾 🕸 👩‍💻 🔢.

### <a href="https://flask.palletsprojects.com" class="external-link" target="_blank">🏺</a>

🏺 "🕸", ⚫️ 🚫 🔌 💽 🛠️ 🚫 📚 👜 👈 👟 🔢 ✳.

FastAPI will use this `response_model` to do all the data documentation, validation, etc. and also to **convert and filter the output data** to its type declaration.

!!! tip
    If you have strict type checks in your editor, mypy, etc, you can declare the function return type as `Any`.