### Injeção de dependência { #dependency-injection }

FastAPI inclui um sistema de <abbr title='também conhecido como "components", "resources", "services", "providers"'><strong>injeção de dependência</strong></abbr> extremamente fácil de usar, mas extremamente poderoso.

* Mesmo dependências podem ter dependências, criando uma hierarquia ou **"grafo" de dependências**.

 * your HTTP calls. This is because each client holds its own connection pool and thread pools.
 * Reusing connections and threads reduces latency and saves memory. Conversely, creating a client
 * for each request wastes resources on idle pools.
 *
 * Use `new OkHttpClient()` to create a shared instance with the default settings:
 *
 * ```java
 * // The singleton HTTP client.
 * public final OkHttpClient client = new OkHttpClient();
 * ```

    * Cookies, 等等。

加上来自 Starlette（包括 **session cookie**）的所有安全特性。

所有的这些都是可复用的工具和组件，可以轻松与你的系统，数据仓库，关系型以及 NoSQL 数据库等等集成。



### 依赖注入

FastAPI 有一个使用非常简单，但是非常强大的<abbr title='也叫做 "components", "resources", "services", "providers"'><strong>依赖注入</strong></abbr>系统。

* 甚至依赖也可以有依赖，创建一个层级或者**“图”依赖**。
* 所有**自动化处理**都由框架完成。
* 所有的依赖关系都可以从请求中获取数据，并且**增加了路径操作**约束和自动文档生成。
* 即使在依赖项中被定义的*路径操作* 也会**自动验证**。

```
/items/foo
```

/// info | Información

Un "path" también es comúnmente llamado "endpoint" o "ruta".

///

Mientras construyes una API, el "path" es la forma principal de separar "concerns" y "resources".

#### Operación { #operation }

"Operación" aquí se refiere a uno de los "métodos" HTTP.

Uno de:

* `POST`
* `GET`
* `PUT`
* `DELETE`

...y los más exóticos:

            stopProactiveHealthChecking();
        }
        log.info("Proactive health checking {}", enabled ? "enabled" : "disabled");
    }

    /**
     * Close the transport pool and cleanup resources
     */
    public void closePool() {
        stopProactiveHealthChecking();
        healthCheckExecutor.shutdown();
        try {
            if (!healthCheckExecutor.awaitTermination(5, TimeUnit.SECONDS)) {

        tuples.add(new Tuple<>(DefaultKeys.SUPPORTED_FIELDS, "content"));
        return tuples;
    }

    /**
     * Loads the index settings from a resource file.
     * @return The index settings as a string.
     * @throws IOException If an I/O error occurs.
     */
    protected String loadIndexSettings() throws IOException {

      }

      /**
       * Returns an input stream containing one or more certificate PEM files. This implementation just
       * embeds the PEM files in Java strings; most applications will instead read this from a resource
       * file that gets bundled with the application.
       */
      private fun trustedCertificatesInputStream(): InputStream {
        ... // Full source omitted. See sample.
      }

        `tf.lookup.StaticHashTable.__init__` to create the table in anonymous
        mode. In this mode, the table resource can only be accessed via resource
        handles (not resource names) and will be deleted automatically when all
        resource handles pointing to it are gone.
*   `tf.data`:
    *   Introduce the `tf.data.experimental.at` API which provides random access

        // Test with extra SIDs flag
        when(logonInfo.getUserFlags()).thenReturn(PacConstants.LOGON_EXTRA_SIDS);
        assertEquals(PacConstants.LOGON_EXTRA_SIDS, logonInfo.getUserFlags());

        // Test with resource groups flag
        when(logonInfo.getUserFlags()).thenReturn(PacConstants.LOGON_RESOURCE_GROUPS);
        assertEquals(PacConstants.LOGON_RESOURCE_GROUPS, logonInfo.getUserFlags());

        // Test with combined flags

	policyBytes := []byte(`{
 "Version": "2012-10-17",
 "Statement": [
  {
   "Effect": "Allow",
   "Action": [
    "s3:PutObject",
    "s3:GetObject",
    "s3:ListBucket"
   ],
   "Resource": [
    "arn:aws:s3:::BUCKET/*"
   ]
  }
 ]
}`)

	err := s.adm.AddCannedPolicy(ctx, policy, policyBytes)
	if err != nil {
		c.Fatalf("policy add error: %v", err)
	}

	{