# API Gateway 中 REST API 的附加映射模板示例
<a name="example-photos"></a>

以下示例显示了 API Gateway 中的相册 API，该 API 使用映射模板转换集成请求和集成响应数据。它还使用数据模型来定义方法请求和集成响应有效载荷。有关数据模型的更多信息，请参阅[针对 REST API 的数据模型](models-mappings-models.md)。

## 方法请求和集成请求
<a name="example-photos-request"></a>

以下是定义方法请求正文的模型。此输入模型要求调用方上传一张照片页面，每页至少需要 10 张照片。您可以使用此输入模型生成 SDK 或为您的 API 使用请求验证。在使用请求验证时，如果方法请求正文不符合模型的数据结构，则 API Gateway 会使请求失败。

```
{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "PhotosInputModel",
  "type": "object",
  "properties": {
    "photos": {
      "type": "object",
      "required" : [
      "photo"
      ],
      "properties": {
        "page": { "type": "integer" },
        "pages": { "type": "string" },
        "perpage": { "type": "integer", "minimum" : 10 },
        "total": { "type": "string" },
        "photo": {
          "type": "array",
          "items": {
            "type": "object",
            "properties": {
              "id": { "type": "string" },
              "owner": { "type": "string" },
              "photographer_first_name" : {"type" : "string"},
              "photographer_last_name" : {"type" : "string"},
              "secret": { "type": "string" },
              "server": { "type": "string" },
              "farm": { "type": "integer" },
              "title": { "type": "string" },
              "ispublic": { "type": "boolean" },
              "isfriend": { "type": "boolean" },
              "isfamily": { "type": "boolean" }
            }
          }
        }
      }
    }
  }
}
```

以下是遵循先前数据模型的数据结构的方法请求正文示例。

```
{
  "photos": {
    "page": 1,
    "pages": "1234",
    "perpage": 100,
    "total": "123398",
    "photo": [
      {
        "id": "12345678901",
        "owner": "23456789@A12",
        "photographer_first_name" : "Saanvi",
        "photographer_last_name" : "Sarkar",
        "secret": "abc123d456",
        "server": "1234",
        "farm": 1,
        "title": "Sample photo 1",
        "ispublic": true,
        "isfriend": false,
        "isfamily": false
      },
      {
        "id": "23456789012",
        "owner": "34567890@B23",
        "photographer_first_name" : "Richard",
        "photographer_last_name" : "Roe",
        "secret": "bcd234e567",
        "server": "2345",
        "farm": 2,
        "title": "Sample photo 2",
        "ispublic": true,
        "isfriend": false,
        "isfamily": false
      }
    ]
  }
}
```

在此示例中，如果之前的方法请求正文是由客户端提交的，则此映射模板会转换有效载荷，以匹配集成端点所需的格式。

```
#set($inputRoot = $input.path('$'))
{
  "photos": [
#foreach($elem in $inputRoot.photos.photo)
    {
      "id": "$elem.id",
      "photographedBy": "$elem.photographer_first_name $elem.photographer_last_name",
      "title": "$elem.title",
      "ispublic": $elem.ispublic,
      "isfriend": $elem.isfriend,
      "isfamily": $elem.isfamily
    }#if($foreach.hasNext),#end
		
#end
  ]
}
```

以下示例是来自转换的输出数据：

```
{
  "photos": [
    {
      "id": "12345678901",
      "photographedBy": "Saanvi Sarkar",
      "title": "Sample photo 1",
      "ispublic": true,
      "isfriend": false,
      "isfamily": false
    },		
    {
      "id": "23456789012",
      "photographedBy": "Richard Roe",
      "title": "Sample photo 2",
      "ispublic": true,
      "isfriend": false,
      "isfamily": false
    }		
  ]
}
```

这些数据发送到集成请求，然后发送到集成端点。

## 集成响应和方法响应
<a name="photos-example-response"></a>

以下是来自集成端点的照片数据的输出模型示例。您可以将此模型用于方法响应模型，这在为 API 生成强类型 SDK 时是必需的。这会导致输出将在 Java 或 Objective-C 中强制转换为适当的类。

```
{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "PhotosOutputModel",
  "type": "object",
  "properties": {
    "photos": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "id": { "type": "string" },
          "photographedBy": { "type": "string" },
          "title": { "type": "string" },
          "ispublic": { "type": "boolean" },
          "isfriend": { "type": "boolean" },
          "isfamily": { "type": "boolean" }
        }
      }
    }
  }
}
```

集成端点可能不会以符合此模型的数据结构的响应进行响应。例如，集成响应可能如下所示：

```
  "photos": [
    {
      "id": "12345678901",
      "photographedBy": "Saanvi Sarkar",
      "title": "Sample photo 1",
      "description": "My sample photo 1",
      "public": true,
      "friend": false,
      "family": false
    },		
    {
      "id": "23456789012",
      "photographedBy": "Richard Roe",
      "title": "Sample photo 2",
      "description": "My sample photo 1",
      "public": true,
      "friend": false,
      "family": false
    }		
  ]
}
```

以下示例映射模板将集成响应数据转换为方法响应所期望的格式：

```
#set($inputRoot = $input.path('$'))
{
  "photos": [
#foreach($elem in $inputRoot.photos.photo)
    {
      "id": "$elem.id",
      "photographedBy": "$elem.photographer_first_name $elem.photographer_last_name",
      "title": "$elem.title",
      "ispublic": $elem.public,
      "isfriend": $elem.friend,
      "isfamily": $elem.family
    }#if($foreach.hasNext),#end
		
#end
  ]
}
```

以下示例是来自转换的输出数据：

```
{
  "photos": [
    {
      "id": "12345678901",
      "photographedBy": "Saanvi Sarkar",
      "title": "Sample photo 1",
      "ispublic": true,
      "isfriend": false,
      "isfamily": false
    },		
    {
      "id": "23456789012",
      "photographedBy": "Richard Roe",
      "title": "Sample photo 2",
      "ispublic": true,
      "isfriend": false,
      "isfamily": false
    }		
  ]
}
```

这些数据发送到方法响应，然后再发送回客户端。