DynamoDb Nested Map Update

Question

After working a bit with DynamoDb I’ve run into an issue that from what I’ve read so far is not really ideal for DynamoDb. So before I make the switch to RDS, I’d like to see if there’s anyway I can achieve what I need with DynamoDb. I’ve also thought about breaking this out into multiple tables for DynamoDb

Below of my Data schema. There is a list nested inside the item. I need to be able to append strings to the list.

{
    “server-id”: “123345678”,
    “server-name”: “my-server”
    “topics”: [
        {
            “name”: “my-topic”,
            “subscribers”: [] //This is what I need to append
        }
     ]
}

Answer 1

Yes, this is possible.

var AWS = require('aws-sdk');
AWS.config.update({region: 'us-east-1'});
var ddb = new AWS.DynamoDB({apiVersion: '2012-08-10'});

var params = {
  ExpressionAttributeNames: {
   "#T": "topics", 
   "#S": "subscribers"
  }, 
  ExpressionAttributeValues: {
    ":vals": {
      L: [
        { N: "123" },
        { N: "456" }
      ]
    }
  }, 
  Key: {
   'server-id': { S: '123345678' }
  }, 
  ReturnValues: "ALL_NEW", 
  TableName: 'dummy-table',
  UpdateExpression: "SET #T[0].#S = list_append(#T[0].#S, :vals)"
 };

ddb.updateItem(params, function(err, data) {
  if (err) {
    console.log("Error", err);
  } else {
    console.log("Success", data);
  }
});