我们将`SessionLocal()`请求的创建和处理放在一个`try`块中。

然后我们在finally块中关闭它。

通过这种方式，我们确保数据库会话在请求后始终关闭，即使在处理请求时出现异常也会关闭。

///

### 关于`request.state`

`request.state`是每个`Request`对象的属性。它用于存储附加到请求本身的任意对象，例如本例中的数据库会话。您可以在[Starlette 的关于`Request`state](https://www.starlette.io/requests/#other-state)的文档中了解更多信息。

对于这种情况下，它帮助我们确保在整个请求中使用单个数据库会话，然后关闭（在中间件中）。

### 使用`yield`依赖项与使用中间件的区别

在此处添加**中间件**与`yield`的依赖项的作用效果类似，但也有一些区别：

**Typer** is het kleine broertje van FastAPI. En het is bedoeld als de **FastAPI van CLI's**. ️

## Vereisten

FastAPI staat op de schouders van reuzen:

* <a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a> voor de webonderdelen.

		case *net.IPNet:
			ip = v.IP
		case *net.IPAddr:
			ip = v.IP
		}

		if ip.To4() != nil {
			localIP4.Add(ip.String())
		}
	}

	// Filter ipList by IPs those do not start with '127.'.
	nonLoopBackIPs := localIP4.FuncMatch(func(ip string, matchString string) bool {
		return !strings.HasPrefix(ip, "127.")
	}, "")
	if len(nonLoopBackIPs) == 0 {

#   which mounts your TensorFlow directory into the container.
#
#   Important: because the container is persistent, you cannot change TFCI
#   variables in between script executions. To forcibly remove the
#   container and start fresh, run "docker rm -f tf". Removing the container
#   destroys some temporary bazel data and causes longer builds.
#
#   You will need the NVIDIA Container Toolkit for GPU testing:

page.thumbnail.purge.max.fetch.size=100
page.score.booster.max.fetch.size=1000
page.searchlog.max.fetch.size=10000

page.searchlist.track.total.hits=true

# search page
paging.search.page.start=0
paging.search.page.size=10
paging.search.page.max.size=100

searchlog.agg.shard.size=-1
searchlog.request.headers=
searchlog.process.batch_size=100

thumbnail.html.image.min.width=100

	//    single part object) and total decrypted object size `decObjSize`
	//
	// 2. the (decrypted) start offset `off` and (decrypted)
	//    length to read `length`
	//
	// These are the inputs to the rest of the algorithm below.

	// Locate the part containing the start of the required range
	var partEnd int
	var cumulativeSum, encCumulativeSum int64
	for i, size := range sizes {

                pb.directory(baseDir);
                pb.redirectErrorStream(true);
            });

            final InputStreamThread it = jobProcess.getInputStreamThread();
            it.start();

            final Process currentProcess = jobProcess.getProcess();
            currentProcess.waitFor();
            it.join(5000);

            final int exitValue = currentProcess.exitValue();

// IsOnline returns true if the peer client is online.
func (client *peerRESTClient) IsOnline() bool {
	conn := client.gridConn()
	if conn == nil {
		return false
	}
	return client.restClient.IsOnline() || conn.State() == grid.StateConnected
}

// Close - marks the client as closed.
func (client *peerRESTClient) Close() error {
	client.restClient.Close()
	return nil
}

	var (
		tx                      = db.getInstance()
		stmt                    = tx.Statement
		modelSchema, joinSchema *schema.Schema
	)

	err := stmt.Parse(model)
	if err != nil {
		return err
	}
	modelSchema = stmt.Schema

	err = stmt.Parse(joinTable)
	if err != nil {
		return err
	}
	joinSchema = stmt.Schema

	relation, ok := modelSchema.Relationships.Relations[field]

	}

	migrate := func(formatPath string, formatData []byte) ([]byte, fs.FileInfo, error) {
		if err = os.WriteFile(formatPath, formatData, 0o666); err != nil {
			return nil, nil, err
		}
		formatFi, err := Lstat(formatPath)
		if err != nil {
			return nil, nil, err
		}
		return formatData, formatFi, nil
	}

	switch version {
	case formatErasureVersionV1: