## 文件化回呼 { #documenting-the-callback }

實際的回呼程式碼會高度依賴你的 API 應用本身。

而且很可能每個應用都差很多。

它可能就只有一兩行，例如：

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

但回呼中最重要的部分，可能是在確保你的 API 使用者（外部開發者）能正確實作「外部 API」，符合「你的 API」在回呼請求 body 中要送出的資料格式，等等。

因此，接下來我們要加上用來「文件化」說明，該「外部 API」應該長什麼樣子，才能接收來自「你的 API」的回呼。

        this.uuid = "${DslContext.uuidPrefix}_${model.projectId}_Stage_${stage.stageName.uuid}"
        this.name = stage.stageName.stageName
        this.description = stage.stageName.description
    }) {
    val specificBuildTypes: List<OsAwareBaseGradleBuildType>

    val performanceTests: List<PerformanceTestsPass>

    val functionalTests: List<OsAwareBaseGradleBuildType>

### 將子模型作為型別使用 { #use-the-submodel-as-a-type }

然後把它作為某個屬性的型別使用：

{* ../../docs_src/body_nested_models/tutorial004_py310.py hl[18] *}

這表示 **FastAPI** 會期望一個類似如下的本文：

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2,
    "tags": ["rock", "metal", "bar"],
    "image": {
        "url": "http://example.com/baz.jpg",
        "name": "The Foo live"
    }
}
```

{* ../../docs_src/body_nested_models/tutorial004_py310.py hl[18] *}

This would mean that **FastAPI** would expect a body similar to:

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2,
    "tags": ["rock", "metal", "bar"],
    "image": {
        "url": "http://example.com/baz.jpg",
        "name": "The Foo live"
    }
}
```

        @DisplayName("should reject invalid version formats")
        void shouldRejectInvalidVersionFormats(String version, String description) {
            assertFalse(
                    ModelVersionUtils.isValidModelVersion(version), "Should reject " + description + ": " + version);
        }

        private static Stream<Arguments> provideInvalidVersions() {
            return Stream.of(

    @get:Optional
    @get:Option(option = "fix", description = "When enabled, will write the correct computed runtimes back to the build files")
    abstract val fix: Property<Boolean>

    /**
     * If enabled, prints extra details describing why a target runtime declaration is invalid.
     */
    @get:Input
    @get:Optional

        StringBuilder sb = new StringBuilder(512);
        boolean odd = true;
        sb.append(
                "<table border='1' class='zebra-striped'><tr class='a'><th><b>Options</b></th><th><b>Description</b></th></tr>");
        for (Option option : new CLIManagerExtension().getOptions()) {
            odd = !odd;
            sb.append("<tr class='");
            sb.append(odd ? 'a' : 'b');
            sb.append("'>");

**FastAPI** generates a "schema" with all your API using the **OpenAPI** standard for defining APIs.

#### "Schema" { #schema }

A "schema" is a definition or description of something. Not the code that implements it, but just an abstract description.

#### API "schema" { #api-schema }

In this case, [OpenAPI](https://github.com/OAI/OpenAPI-Specification) is a specification that dictates how to define a schema of your API.

     * Maximum length is 20 characters.
     */
    @Required
    @Size(max = 20)
    public String sessionId;

    /**
     * The name or description of the crawling session.
     * This is an optional descriptive field with a maximum length of 20 characters.
     */
    @Size(max = 20)
    public String name;

    /**

    }

    public interface ContentTransformer {
        /**
         * Interpolate the value read from the xpp3 document
         *
         * @param source The source value
         * @param fieldName A description of the field being interpolated. The implementation may use this to
         *         log stuff.
         * @return The interpolated value.
         */
        String transform(String source, String fieldName);
    }