PHP调用DynamoDB getItem接口遇键元素与Schema不匹配错误求助

问题概述 #

调用DynamoDB的GetItem接口获取数据时，返回400 Bad Request错误，提示「提供的键元素与架构不匹配」。

数据示例 #

{
 "section_id": "6177d23bb5f04ca363fe3d91",
 "chapter_id": "6177ccd4b5f04ca363fe3d63",
 "data": {
 }
}

调用代码 #

$sdk = $this->sdk();
$dynamodb = $sdk->createDynamoDb();

$result = $dynamodb->getItem(
    array(
        'TableName' => 'sections',
        'Key'   => array(
            'section_id'   => array(
                'S' => '6177d23bb5f04ca363fe3d91'
            )
        )
    )
);
print_r($result);
exit;

错误信息 #

类型: Aws\DynamoDb\Exception\DynamoDbException
消息: 执行 "GetItem" 接口时出错，请求地址：https://dynamodb.ap-south-1.amazonaws.com；AWS HTTP错误：客户端错误：`POST https://dynamodb.ap-south-1.amazonaws.com` 返回 `400 Bad Request` 响应：{"__type":"com.amazon.coral.validate#ValidationException","message":"提供的键元素与架构不匹配"（已截断...）ValidationException (客户端): 提供的键元素与架构不匹配 - {"__type":"com.amazon.coral.validate#ValidationException","message":"提供的键元素与架构不匹配"}

解决方案 #

DynamoDB的GetItem接口要求必须传入完整的主键（如果是复合主键，则需要同时提供分区键和排序键）。从数据示例可以看出，sections表的主键是复合主键：section_id为分区键，chapter_id为排序键。原代码只传入了section_id，缺少排序键chapter_id，导致与表的架构不匹配。

修改后的代码如下：

$sdk = $this->sdk();
$dynamodb = $sdk->createDynamoDb();

$result = $dynamodb->getItem(
    array(
        'TableName' => 'sections',
        'Key'   => array(
            'section_id'   => array(
                'S' => '6177d23bb5f04ca363fe3d91'
            ),
            'chapter_id' => array(
                'S' => '6177ccd4b5f04ca363fe3d63'
            )
        )
    )
);
print_r($result);
exit;

内容的提问来源于stack exchange，提问作者Sathishkumar