# 事件：启动 - 关闭

**FastAPI** 支持定义在应用启动前，或应用关闭后执行的事件处理器（函数）。

事件函数既可以声明为异步函数（`async def`），也可以声明为普通函数（`def`）。

!!! warning "警告"

    **FastAPI** 只执行主应用中的事件处理器，不执行[子应用 - 挂载](sub-applications.md){.internal-link target=_blank}中的事件处理器。

## `startup` 事件

使用 `startup` 事件声明 `app` 启动前运行的函数：

```Python hl_lines="8"
{!../../../docs_src/events/tutorial001.py!}
```

本例中，`startup` 事件处理器函数为项目数据库（只是**字典**）提供了一些初始值。

**FastAPI** 支持多个事件处理器函数。

# 이벤트: startup과 shutdown

필요에 따라 응용 프로그램이 시작되기 전이나 종료될 때 실행되는 이벤트 핸들러(함수)를 정의할 수 있습니다.

이 함수들은 `async def` 또는 평범하게 `def`으로 선언할 수 있습니다.

!!! warning "경고"
    이벤트 핸들러는 주 응용 프로그램에서만 작동합니다. [하위 응용 프로그램 - 마운트](./sub-applications.md){.internal-link target=_blank}에서는 작동하지 않습니다.

## `startup` 이벤트

응용 프로그램을 시작하기 전에 실행하려는 함수를 "startup" 이벤트로 선언합니다:

```Python hl_lines="8"
{!../../../docs_src/events/tutorial001.py!}
```

```Python hl_lines="3  5"
{!../../../docs_src/dependencies/tutorial007.py!}
```

## Sub-dependencies with `yield`

You can have sub-dependencies and "trees" of sub-dependencies of any size and shape, and any or all of them can use `yield`.

**FastAPI** will make sure that the "exit code" in each dependency with `yield` is run in the correct order.

> NOTE: MinIO environmental variables still take precedence over the `config.yaml` file, however `config.yaml` is preferred over MinIO internal config KV settings via `mc admin config set alias/ <sub-system>`.

### TODO

In subsequent releases we are planning to extend this to provide things like

- Reload() of MinIO server arguments without fully restarting the process.

- The helping message of commands which have sub-commands is now clearer and more instructive. It will show the full command instead of `kubectl <command> --help ...`
  

`FastAPI` aslında `Starlette`'nin bir sub-class'ı. Eğer Starlette'nin nasıl kullanılacağını biliyor isen, çoğu işlevini aynı şekilde yapıyor.

**FastAPI** ile beraber **Starlette**'nin bütün özelliklerine de sahip olacaksınız (FastAPI aslında Starlette'nin steroid basmış hali):

## Request, System and Cluster Metrics

At a high level metrics are grouped into three categories, listed in the following sub-sections. The path in each of the tables is relative to the top-level endpoint.

### Request metrics 

These are metrics about requests served by the (current) node.

```

#### `RequestValidationError` vs `ValidationError`

!!! warning
    These are technical details that you might skip if it's not important for you now.

`RequestValidationError` is a sub-class of Pydantic's <a href="https://docs.pydantic.dev/latest/concepts/models/#error-handling" class="external-link" target="_blank">`ValidationError`</a>.

If you pass a "callable" as a dependency in **FastAPI**, it will analyze the parameters for that "callable", and process them in the same way as the parameters for a *path operation function*. Including sub-dependencies.

That also applies to callables with no parameters at all. The same as it would be for *path operation functions* with no parameters.

!!! tip
    There's an equivalent article using Peewee here in the docs.

## File structure

For these examples, let's say you have a directory named `my_super_project` that contains a sub-directory called `sql_app` with a structure like this:

```
.
└── sql_app
    ├── __init__.py
    ├── crud.py
    ├── database.py
    ├── main.py
    ├── models.py
    └── schemas.py
```