```Python hl_lines="1  3" title="app/routers/users.py"
{!../../../docs_src/bigger_applications/app/routers/users.py!}
```

### *Path operations* with `APIRouter`

And then you use it to declare your *path operations*.

Use it the same way you would use the `FastAPI` class:

```Python hl_lines="6  11  16" title="app/routers/users.py"
{!../../../docs_src/bigger_applications/app/routers/users.py!}
```

你可以导入它并通过与 `FastAPI` 类相同的方式创建一个「实例」：

```Python hl_lines="1  3" title="app/routers/users.py"
{!../../../docs_src/bigger_applications/app/routers/users.py!}
```

### 使用 `APIRouter` 的*路径操作*

然后你可以使用它来声明*路径操作*。

使用方式与 `FastAPI` 类相同：

```Python hl_lines="6  11  16" title="app/routers/users.py"
{!../../../docs_src/bigger_applications/app/routers/users.py!}
```

你可以将 `APIRouter` 视为一个「迷你 `FastAPI`」类。

所有相同的选项都得到支持。

          if (!buffer.isProbablyUtf8()) {
            logger.log("")
            logger.log("<-- END HTTP (${totalMs}ms, binary ${buffer.size}-byte body omitted)")
            return response
          }

          if (contentLength != 0L) {
            logger.log("")
            logger.log(buffer.clone().readString(charset))
          }

          logger.log(
            buildString {

      protocol: ByteString,
      host: String,
      port: Int,
      maxAge: Long,
    ) {
      throw UnsupportedOperationException()
    }
  }

  companion object {
    private val logger = Logger.getLogger(MockHttp2Peer::class.java.name)
  }

            handler.formatter = MessageFormatter
            activeLogger.addHandler(handler)
          }
        }
      }
    }

    fun getLogger(name: String): Logger {
      val logger = Logger.getLogger(name)
      activeLoggers.add(logger)
      return logger
    }
  }

And your **FastAPI** application might also be composed of several files/modules, etc.

### **FastAPI** app file

Let's say you have a file structure as described in [Bigger Applications](bigger-applications.md){.internal-link target=_blank}:

```
.
├── app
│   ├── __init__.py
│   └── main.py
```

In the file `main.py` you have your **FastAPI** app:


```Python

The client will get a **500 Internal Server Error** for that request, but the application will continue working for the next requests instead of just crashing completely.

### Bigger Errors - Crashes

Nevertheless, there might be cases where we write some code that **crashes the entire application** making Uvicorn and Python crash. 💥

The response object will also have autocompletion:

<img src="/img/tutorial/generate-clients/image05.png">

## FastAPI App with Tags

In many cases your FastAPI app will be bigger, and you will probably use tags to separate different groups of *path operations*.

For example, you could have a section for **items** and another section for **users**, and they could be separated by tags:

        api("com.nhaarman:mockito-kotlin:1.6.0")
        api("com.thoughtworks.qdox:qdox:2.0.3")
        api("com.uwyn:jhighlight:1.0")
        api("com.vladsch.flexmark:flexmark-all:0.34.60") {
            because("Higher versions tested are either incompatible (0.62.2) or bring additional unwanted dependencies (0.36.8)")
        }
        api("org.apache.pdfbox:pdfbox:2.0.24") {

  Otherwise, native-only dependencies may not be added to the verification metadata. This is because `local.properties` has higher 
  precedence than the `-Pkotlin.native.enabled=true` specified in the Gradle command.

## Using -dev versions

We publish `-dev` versions frequently.