Here we declare the setting `openapi_url` with the same default of `"/openapi.json"`.

And then we use it when creating the `FastAPI` app.

Then you could disable OpenAPI (including the UI docs) by setting the environment variable `OPENAPI_URL` to the empty string, like:

<div class="termy">

```console
$ OPENAPI_URL= uvicorn main:app

{* ../../docs_src/header_param_models/tutorial001_an_py310.py hl[9:14,18] *}

**FastAPI** 将从请求中接收到的 **headers** 中**提取**出**每个字段**的数据，并提供您定义的 Pydantic 模型。

## 查看文档 { #check-the-docs }

您可以在文档 UI 的 `/docs` 中查看所需的 headers：

<div class="screenshot">
<img src="/img/tutorial/header-param-models/image01.png">
</div>

## 禁止额外的 Headers { #forbid-extra-headers }

在某些特殊使用情况下（可能并不常见），您可能希望**限制**您想要接收的 headers。

# Also ignore protoc installed by hack/install-protoc.sh
/third_party/protoc*

# User cluster configs
.kubeconfig

.tags*

# Version file for dockerized build
.dockerized-kube-version-defs

# Web UI
/www/master/node_modules/
/www/master/npm-debug.log
/www/master/shared/config/development.json

# Karma output
/www/test_out

func (c *Config) Registered() bool {
	configLock.RLock()
	defer configLock.RUnlock()

	return len(c.APIKey) > 0
}

// ApplyEnv - applies the current subnet config to Console UI specific environment variables.
func (c *Config) ApplyEnv() {
	configLock.RLock()
	defer configLock.RUnlock()

	if c.License != "" {
		os.Setenv("CONSOLE_SUBNET_LICENSE", c.License)
	}
	if c.APIKey != "" {

            Doc(
                """
                OAuth2 configuration for the Swagger UI, by default shown at `/docs`.

                Read more about the available configuration options in the
                [Swagger UI docs](https://swagger.io/docs/open-source-tools/swagger-ui/usage/oauth2/).
                """
            ),
        ] = None,
        middleware: Annotated[

That way, the sub-application will know to use that path prefix for the docs UI.

And the sub-application could also have its own mounted sub-applications and everything would work correctly, because FastAPI handles all these `root_path`s automatically.

**FastAPI** will **extract** the data for **each field** from the **headers** in the request and give you the Pydantic model you defined.

## Check the Docs { #check-the-docs }

You can see the required headers in the docs UI at `/docs`:

<div class="screenshot">
<img src="/img/tutorial/header-param-models/image01.png">
</div>

## Forbid Extra Headers { #forbid-extra-headers }

{* ../../docs_src/openapi_webhooks/tutorial001_py310.py hl[9:12,15:20] *}

The webhooks that you define will end up in the **OpenAPI** schema and the automatic **docs UI**.

/// info

The `app.webhooks` object is actually just an `APIRouter`, the same type you would use when structuring your app with multiple files.

///

{* ../../docs_src/request_form_models/tutorial001_an_py310.py hl[9:11,15] *}

**FastAPI** 将从请求中的**表单数据**中**提取**出**每个字段**的数据，并提供你定义的 Pydantic 模型。

## 检查文档 { #check-the-docs }

你可以在文档 UI 中验证它，地址为 `/docs`：

<div class="screenshot">
<img src="/img/tutorial/request-form-models/image01.png">
</div>

## 禁止额外的表单字段 { #forbid-extra-form-fields }

后来，Swagger 交由 Linux 基金会管理，并更名为 OpenAPI。

因此，在谈到 2.0 版本时人们常说 “Swagger”，而 3+ 版本则称为 “OpenAPI”。

/// check | 启发 **FastAPI**：

采用并使用开放的 API 规范标准，而非自定义模式。

并集成基于标准的用户界面工具：

* [Swagger UI](https://github.com/swagger-api/swagger-ui)
* [ReDoc](https://github.com/Rebilly/ReDoc)

选择这两者是因为它们相当流行且稳定；但稍作搜索，你就能找到数十种 OpenAPI 的替代用户界面（都可以与 **FastAPI** 搭配使用）。

///

### Flask REST 框架 { #flask-rest-frameworks }