How to insert json in dynamodb

Question

Here's my code.
I want to insert asset_data json into asset_data column. i am using aws sdk. It says aws sdk now has support for json. http://aws.amazon.com/releasenotes/SDK/JavaScript/1691866671551861

var asset_data = {
    "name": "name" + i,
    "contentUrl": "http://www.hdwallpapersimages.com/nature-beauty-desktop-images/94892/",
    "size": 300,
    "headline": "headline",
    "description": "assetUrl reference for the creator",
    "encodingFormat": 'jpeg'
  };

  var params = {
    TableName: 'xyz',
    Item: { // a map of attribute name to AttributeValue
      "asset_id": {S: "asset" + i},
      "hit_id": {S: "0"},
      "created_date": {"S": Date.now().toString()},
      "status": {N: "0"},
      "operation": {S: "image_tagging"},
      "asset_data": {L: asset_data},
      "source": {S: "DAM"},
      "completed_date": {S: Date.now().toString()},
      "response_data": {S: "taged value"}
      // more attributes...
    },

    ReturnValues: 'NONE', // optional (NONE | ALL_OLD)
    ReturnConsumedCapacity: 'NONE', // optional (NONE | TOTAL | INDEXES)
    ReturnItemCollectionMetrics: 'NONE' // optional (NONE | SIZE)
  };

  db.putItem(params, function (err, data) {
    if (err) console.log(err); // an error occurred
    else console.log("inserted..."); // successful response
  });

Answer 1

You can use the DynamoDB Document Client SDK:

http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/DynamoDB/DocumentClient.html#put-property

The document client simplifies working with items in Amazon DynamoDB by abstracting away the notion of attribute values. This abstraction annotates native JavaScript types supplied as input parameters, as well as converts annotated response data to native JavaScript types.

For your case specifically look at the Map Attribute value (M) being passed as MapAttribute in the example below extracted from the official documentation. The Document Client API takes care of the proper marshalling/unmarshalling between the Javascript and DynamoDB types (meaning that you don't have to specify the Attribute Values (S,N,L,...) as it is required when using the non-document based SDK ):

var params = {
  TableName: 'Table',
  Item: {
     HashKey: 'haskey',
     NumAttribute: 1,
     BoolAttribute: true,
     ListAttribute: [1, 'two', false],
     MapAttribute: { foo: 'bar'},
     NullAttribute: null
  }
};

var docClient = new AWS.DynamoDB.DocumentClient();

docClient.put(params, function(err, data) {
  if (err) console.log(err);
  else console.log(data);
});