在开发 API 时，你通常使用特定的 HTTP 方法去执行特定的行为。

通常使用：

* `POST`：创建数据。
* `GET`：读取数据。
* `PUT`：更新数据。
* `DELETE`：删除数据。

因此，在 OpenAPI 中，每一个 HTTP 方法都被称为「操作」。

我们也打算称呼它们为「操作」。

#### 定义一个*路径操作装饰器* { #define-a-path-operation-decorator }

{* ../../docs_src/first_steps/tutorial001_py310.py hl[6] *}

`@app.get("/")` 告诉 **FastAPI** 在它下方的函数负责处理如下访问请求：

* 请求路径为 `/`

Guava, the best approach is to create an [issue][] (or comment on an existing
issue if there is one) requesting the feature and describing specific use cases
for it.

If we decide to pursue a feature request, it will go through a thorough process
of API design and review. Any code should come after this.

[APIs]: https://en.wikipedia.org/wiki/API
[issue]: https://github.com/google/guava/issues

        valueSources.add(new MapBasedValueSource(config.getUserProperties()));

        // Overwrite existing values in model properties. Otherwise, it's not possible
        // to define them via command line e.g.: mvn -Drevision=6.5.7 ...
        versionProcessor.overwriteModelProperties(modelProperties, config);
        valueSources.add(new MapBasedValueSource(modelProperties));

```
http://127.0.0.1:8000/items/foo-item?needy=sooooneedy
```

...this would work:

```JSON
{
    "item_id": "foo-item",
    "needy": "sooooneedy"
}
```

And of course, you can define some parameters as required, some as having a default value, and some entirely optional:

{* ../../docs_src/query_params/tutorial006_py310.py hl[8] *}

In this case, there are 3 query parameters:

* `PUT`: щоб оновити дані.
* `DELETE`: щоб видалити дані.

Отже, в OpenAPI кожен з HTTP методів називається «операцією».

Ми також будемо називати їх «**операціями**».

#### Визначте *декоратор операції шляху* { #define-a-path-operation-decorator }

{* ../../docs_src/first_steps/tutorial001_py310.py hl[6] *}

Декоратор `@app.get("/")` повідомляє **FastAPI**, що функція одразу нижче відповідає за обробку запитів, які надходять до:

    <suppress checks="JavadocPackage"
              files=".*[/\\]platforms[/\\]ide[/\\]ide-plugins[/\\]src[/\\]main[/\\]java[/\\]org[/\\]gradle[/\\]plugins[/\\]ide[/\\]eclipse[/\\][^/\\]+"/>

    <!-- Protocol types may only define constants in interfaces -->
    <suppress checks="InterfaceIsTypeCheck"
              files=".*[/\\]tooling-api[/\\]src[/\\]main[/\\]java[/\\]org[/\\]gradle[/\\]tooling[/\\]internal[/\\]protocol.+"/>

SAM Conversions
---------------

When you use Java APIs from Kotlin you can operate on Java interfaces as if they were Kotlin
lambdas. The [feature][java_sams] is available for interfaces that define a Single Abstract Method
(SAM).

But when you use Kotlin APIs from Kotlin there’s no automatic conversion. Code that used SAM lambdas
with OkHttp 3.x: must use `object :` with OkHttp 4.x:

Kotlin calling OkHttp 3.x:

     *
     * @param <P>           the type of problem
     * @param maxCountLimit the maximum number of problems to preserve
     * @param filter        predicate to decide which problems to record
     * @return a new filtered problem collector instance
     */
    @Nonnull
    static <P extends BuilderProblem> ProblemCollector<P> create(int maxCountLimit, Predicate<? super P> filter) {

Avec cela, vous devriez avoir une compréhension de base de ce que sont les **variables d'environnement** et de la façon de les utiliser en Python.

Vous pouvez également en lire davantage sur la [page Wikipédia dédiée aux variables d'environnement](https://en.wikipedia.org/wiki/Environment_variable).

# Eventos de lifespan { #lifespan-events }

Você pode definir a lógica (código) que deve ser executada antes da aplicação **inicializar**. Isso significa que esse código será executado **uma vez**, **antes** de a aplicação **começar a receber requisições**.