You could also use it to generate code automatically, for clients that communicate with your API. For example, frontend, mobile or IoT applications.

## Recap, step by step

### Step 1: import `FastAPI`

```Python hl_lines="1"
{!../../../docs_src/first_steps/tutorial001.py!}
```

`FastAPI` is a Python class that provides all the functionality for your API.

        Doc(
            """
            'Whitelist' validation step. The parameter field will be the single one
            allowed by the alias or set of aliases defined.
            """
        ),
    ] = None,
    serialization_alias: Annotated[
        Union[str, None],
        Doc(
            """
            'Blacklist' validation step. The vanilla parameter field will be the

## ステップ毎の要約

### Step 1: `FastAPI`をインポート

```Python hl_lines="1"
{!../../../docs_src/first_steps/tutorial001.py!}
```

`FastAPI`は、APIのすべての機能を提供するPythonクラスです。

!!! note "技術詳細"
    `FastAPI`は`Starlette`を直接継承するクラスです。

    `FastAPI`でも<a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a>のすべての機能を利用可能です。

### Step 2: `FastAPI`の「インスタンス」を生成

It used custom types in its declarations instead of standard Python types, but it was still a huge step forward.

It also was one of the first frameworks to generate a custom schema declaring the whole API in JSON.

* 🌐 Remove Vietnamese note about missing translation. PR [#9957](https://github.com/tiangolo/fastapi/pull/9957) by [@tiangolo](https://github.com/tiangolo).

### Internal

* 👷 Add GitHub Actions step dump context to debug external failures. PR [#10008](https://github.com/tiangolo/fastapi/pull/10008) by [@tiangolo](https://github.com/tiangolo).

In the end, a hierarchical tree of dependencies is built, and the **Dependency Injection** system takes care of solving all these dependencies for you (and their sub-dependencies) and providing (injecting) the results at each step.

For example, let's say you have 4 API endpoints (*path operations*):

* `/items/public/`
* `/items/private/`
* `/users/{user_id}/activate`
* `/items/pro/`

  - author: Keshav Malik
    author_link: https://theinfosecguy.xyz/
    link: https://blog.theinfosecguy.xyz/building-a-crud-api-with-fastapi-and-supabase-a-step-by-step-guide
    title: Building a CRUD API with FastAPI and Supabase
  - author: Adejumo Ridwan Suleiman
    author_link: https://www.linkedin.com/in/adejumoridwan/

Then you go to the counter 🔀, to the initial task that is now finished ⏯, pick the burgers, say thanks and take them to the table. That finishes that step / task of interaction with the counter ⏹. That in turn, creates a new task, of "eating burgers" 🔀 ⏯, but the previous one of "getting burgers" is finished ⏹.

### Parallel Burgers

# Tutorial - User Guide

This tutorial shows you how to use **FastAPI** with most of its features, step by step.

Each section gradually builds on the previous ones, but it's structured to separate topics, so that you can go directly to any specific one to solve your specific API needs.

It is also built to work as a future reference.

So you can come back and see exactly what you need.

## Run the code

    The `--upgrade` option tells `pip` to upgrade the packages if they are already installed.

    Because the previous step copying the file could be detected by the **Docker cache**, this step will also **use the Docker cache** when available.