"content": {
                "application/json": {
                    "schema": {
                        "$ref": "#/components/schemas/Message"
                    }
                }
            }
        },
        "200": {
            "description": "Successful Response",
            "content": {
                "application/json": {
                    "schema": {

That's what would happen to a third party application that tried to access one of these *path operations* with a token provided by a user, depending on how many permissions the user gave the application.

## About third party integrations

In this example we are using the OAuth2 "password" flow.

This is appropriate when we are logging in to our own application, probably with our own frontend.

## Separating tests

In a real application, you probably would have your tests in a different file.

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

<span style="color: green;">INFO</span>:     Started server process [28722]
<span style="color: green;">INFO</span>:     Waiting for application startup.
<span style="color: green;">INFO</span>:     Application startup complete.
```

</div>

**SANGAT disarankan** agar kamu menulis atau menyalin kode, mengubahnya dan menjalankannya secara lokal.

    // Type1 ::= VisibleString
    // Type2 ::= [APPLICATION 3] IMPLICIT Type1
    // Type3 ::= [2] Type2
    // Type4 ::= [APPLICATION 7] IMPLICIT Type3
    val buffer = Buffer()
    val derWriter = DerWriter(buffer)

    derWriter.write("test", tagClass = DerHeader.TAG_CLASS_APPLICATION, tag = 7L) {
      derWriter.write("test", tagClass = DerHeader.TAG_CLASS_APPLICATION, tag = 3L) {

```Python hl_lines="9"
{!../../../docs_src/behind_a_proxy/tutorial004.py!}
```

and then it won't include it in the OpenAPI schema.

## Mounting a sub-application

If you need to mount a sub-application (as described in [Sub Applications - Mounts](sub-applications.md){.internal-link target=_blank}) while also using a proxy with `root_path`, you can do it normally, as you would expect.

import okhttp3.internal.connection.RealCall

/**
 * A concrete interceptor chain that carries the entire interceptor chain: all application
 * interceptors, the OkHttp core, all network interceptors, and finally the network caller.
 *
 * If the chain is for an application interceptor then [exchange] must be null. Otherwise it is for
 * a network interceptor and [exchange] must be non-null.
 */
class RealInterceptorChain(

<span style="color: green;">INFO</span>:     Started server process [28722]
<span style="color: green;">INFO</span>:     Waiting for application startup.
<span style="color: green;">INFO</span>:     Application startup complete.
```

</div>

Se **RECOMIENDA** que escribas o copies el código, lo edites y lo ejecutes localmente.

You can add middleware to **FastAPI** applications.

A "middleware" is a function that works with every **request** before it is processed by any specific *path operation*. And also with every **response** before returning it.

* It takes each **request** that comes to your application.
* It can then do something to that **request** or run any needed code.
* Then it passes the **request** to be processed by the rest of the application (by some *path operation*).

例如，您可以添加一个额外的媒体类型` image/png` ，声明您的路径操作可以返回JSON对象（媒体类型 `application/json` ）或PNG图像：

```Python hl_lines="19-24  28"
{!../../../docs_src/additional_responses/tutorial002.py!}
```

!!! Note
	- 请注意，您必须直接使用 `FileResponse` 返回图像。

!!! Info
	- 除非在 `responses` 参数中明确指定不同的媒体类型，否则**FastAPI**将假定响应与主响应类具有相同的媒体类型（默认为` application/json` ）。
	- 但是如果您指定了一个自定义响应类，并将 `None `作为其媒体类型，**FastAPI**将使用 `application/json` 作为具有关联模型的任何其他响应。

## 组合信息