They are, more or less, at opposite ends, complementing each other.

Requests has a very simple and intuitive design, it's very easy to use, with sensible defaults. But at the same time, it's very powerful and customizable.

That's why, as said in the official website:

> Requests is one of the most downloaded Python packages of all time

The way you use it is very simple. For example, to do a `GET` request, you would write:

```Python

<div class="termy">

```console
$ python -m pip install --upgrade pip

---> 100%
```

</div>

!!! tip
    Every time you install a new package with `pip` under that environment, activate the environment again.

In this case, it might not be a problem, because it's the same user sending the password.

But if we use the same model for another *path operation*, we could be sending our user's passwords to every client.

!!! danger
    Never store the plain password of a user or send it in a response like this, unless you know all the caveats and you know what you are doing.

## Add an output model

There are many tools to generate clients from **OpenAPI**.

A common tool is <a href="https://openapi-generator.tech/" class="external-link" target="_blank">OpenAPI Generator</a>.

If you are building a **frontend**, a very interesting alternative is <a href="https://github.com/hey-api/openapi-ts" class="external-link" target="_blank">openapi-ts</a>.

## Client and SDK Generators - Sponsor

    ...
```

!!! info
    如果您需要异步连接到关系数据库，请参阅[Async SQL (Relational) Databases](https://fastapi.tiangolo.com/zh/advanced/async-sql-databases/)

!!! note "Very Technical Details"
    如果您很好奇并且拥有深厚的技术知识，您可以在[Async](https://fastapi.tiangolo.com/zh/async/#very-technical-details)文档中查看有关如何处理 `async def`于`def`差别的技术细节。

## 迁移

因为我们直接使用 SQLAlchemy，并且我们不需要任何类型的插件来使用**FastAPI**，所以我们可以直接将数据库迁移至[Alembic](https://alembic.sqlalchemy.org/)进行集成。

This is just a **quick tutorial / refresher** about Python type hints. It covers only the minimum necessary to use them with **FastAPI**... which is actually very little.

**FastAPI** is all based on these type hints, they give it many advantages and benefits.

But even if you never use **FastAPI**, you would benefit from learning a bit about them.

!!! note

If you have an API that does a comparable amount of computations every time and you have a lot of clients, then the **CPU utilization** will probably *also be stable* (instead of constantly going up and down quickly).

### Examples of Replication Tools and Strategies

    * As we said above, only one process can be listening on a specific IP and port.
    * This is one of the reasons why it's very useful when the same TLS Termination Proxy also takes care of the certificate renewal process.

{!../../../docs_src/bigger_applications/app/main.py!}
```

and it will work correctly, together with all the other *path operations* added with `app.include_router()`.

!!! info "Very Technical Details"
    **Note**: this is a very technical detail that you probably can **just skip**.

    ---

    The `APIRouter`s are not "mounted", they are not isolated from the rest of the application.

# Dependencies

**FastAPI** has a very powerful but intuitive **<abbr title="also known as components, resources, providers, services, injectables">Dependency Injection</abbr>** system.

It is designed to be very simple to use, and to make it very easy for any developer to integrate other components with **FastAPI**.

## What is "Dependency Injection"