title: How return JSON object from DynamoDB with appsync?
body: <p>How I can get JSON object in response from DynamoDB ? I store data in DB as array of object  in format JSON. I have next mapping template request</p>
  
  <pre><code>{
    "version": "2017-02-28",
    "operation": "PutItem",
    "key": {
    "userId": {
      "S":  "$context.identity.username"
    }
  },
    #set( $attrs = $util.dynamodb.toMapValues($ctx.args))
    #set( $attrs.categories = $util.dynamodb.toDynamoDB($ctx.args.categories))
  
    "attributeValues": $util.toJson($attrs)
  }
  </code></pre>
  
  <p>and mapping template response</p>
  
  <pre><code>#set( $result = $ctx.result)
  #set( $result.categories = $util.parseJson($ctx.result.categories))
  $util.toJson($result)
  </code></pre>
  
  <p>but I got response in the format DynamoDB JSON </p>
  
  <pre><code>"createItem": {
        "title": "Test 1",
         "categories": "[{name=food, id=2}, {name=eat, id=1}]"
      }
  </code></pre>
  
  <p>in dynamoDB date save as </p>
  
  <pre><code>"categories": {
      "L": [
        {
          "M": {
            "id": {
              "S": "2"
            },
            "name": {
              "S": "food"
            }
          }
        },
        {
          "M": {
            "id": {
              "S": "1"
            },
            "name": {
              "S": "eat"
            }
          }
        }
      ]
    }
  </code></pre>
  
  <p>How parse it to normal JSON or object ? </p>