How do I use batchWriteItem with Node.js to query AWS DynamoDB?

Question

I'm new to AWS and I'm having problems trying to develop a simple Lambda function with Node.js. In DynamoDB, I have a table named Game with 3 attributes: gamepk, user, result. In just one single execution of the Lambda function, I want to insert a collection of game elements (the number of elements in the collection could vary). I had been reading some tutorials and it said I should use batchWriteItem, but because the collection of Game elements is variable I don't know how to proceed.

Could somebody write a function in Node.js that solves my problem?

An example of the JSON that the lambda function receives is this one:

    {
        "games": [{
                "gamepk": "1",
                "user": "rolo",
                "result": "1-0"

            },
            {
                "gamepk": "2",
                "user": "jhon",
                "result": "1-1"
            }
        ]
    }

Solution 1

This should get you what you need.

1. Create a New Lambda Function
2. Select Node Version 6
3. Select a Role or Create a New one that has DynamoDB Access to Write!
4. Open Created Function in the Web Console

5. Paste the Snippet Bellow into the Cloud 9 Editor

   const AWS = require('aws-sdk/global');
   
   exports.handler = (event, context, callback) => {
   // The event parameter is the input to your lambda function
   console.log(JSON.stringify(event));
   let lambdaInput = event['PROPERTY_NAME_DEFINED_IN_POST'];
   let games = [];
   let documentClient = new AWS.DynamoDB.DocumentClient();
   
   lambda.forEach(item => {
     games.push({
       PutRequest: {
         Item: {
           gamepk: item['gamepk'],
           user: item['user'],
           result: item['result']
         }
       }
     });
   });
   
   let params = {
       RequestItems: {
           'TABLE_NAME': games
       }
   };
   
   documentClient.batchWrite(params, function(err, data) {
       if (err) {
           callback(err);
       } else {
           callback(null, data);
       }
   });
   }
   

Save the Function and then you are going to want to select the drop down at the top that says 'Select a Test Event' and then select 'Configure Test Events'.

This will open a new dialog, just save the JSON that is in the main text area and give the test a Name and Save it.

Now select that test that you just made from the 'Select a Test Event' drop down and then click 'Test' in the top right.

This documentation could be found at AWS Javascript SDK

Solution 2

As an additional help for the answer , you can use an environment variable and use it in the following way:

const MI_TABLE = process.env.MI_TABLE

  let params = {
      RequestItems: {
           [ MI_TABLE ] : games
      }
  };

return await batchWrite(params);