dynamoDBtoCSV.js

var program = require('commander');
var AWS = require('aws-sdk');
var unmarshalItem = require('dynamodb-marshaler').unmarshalItem;
var unmarshal = require('dynamodb-marshaler').unmarshal;
var Papa = require('papaparse');
var headers = [];
var unMarshalledArray = [];
var firstRun = true;

program
  .version('0.0.1')
  .option('-t, --table [tablename]', 'Add the table you want to output to csv')
  .option("-d, --describe")
  .option("-r, --region [regionname]")
  .option("-e, --endpoint [url]", 'Endpoint URL, can be used to dump from local DynamoDB')
  .option("-p, --profile [profile]", 'Use profile from your credentials file')
  .parse(process.argv);

if (!program.table) {
  console.log("You must specify a table");
  program.outputHelp();
  process.exit(1);
}


if (program.region && AWS.config.credentials) {
  AWS.config.update({region: program.region});
} else {
  AWS.config.loadFromPath(__dirname + '/config.json');
}

if (program.endpoint) {
  AWS.config.update({endpoint: program.endpoint})
}

if (program.profile) {
  var newCreds = AWS.config.credentials;
  newCreds.profile = program.profile;
  AWS.config.update({credentials: newCreds});
}

var dynamoDB = new AWS.DynamoDB();

var query = {
  "TableName": program.table,
  "Limit": 1000
};

var describeTable = function(query) {

  dynamoDB.describeTable({
    "TableName": program.table
  }, function(err, data) {

    if (!err) {

      console.dir(data.Table);

    } else console.dir(err);
  });
}


var scanDynamoDB = function ( query ) {

  dynamoDB.scan( query, function ( err, data ) {

    if ( !err ) {
      unMarshalIntoArray( data.Items ); // Print out the subset of results.
      if ( data.LastEvaluatedKey ) { // Result is incomplete; there is more to come.
        query.ExclusiveStartKey = data.LastEvaluatedKey;
        scanDynamoDB(query);
      }
    }
    else {
      console.dir(err);
    }
  });
};

function unMarshalIntoArray( items ) {
  if ( items.length === 0 )
    return;

  items.forEach( function ( row ) {
    let newRow = {};

    // console.log( 'Row: ' + JSON.stringify( row ));
    Object.keys( row ).forEach( function ( key ) {
      if ( headers.indexOf( key.trim() ) === -1 ) {
        // console.log( 'putting new key ' + key.trim() + ' into headers ' + headers.toString());
        headers.push( key.trim() );
      }
      let newValue = unmarshal( row[key] );

      if ( typeof newValue === 'object' ) {
        newRow[key] = JSON.stringify( newValue );
      }
      else {
        newRow[key] = newValue;
      }
    });

    // console.log( newRow );
    unMarshalledArray.push( newRow );

  });

  if (firstRun) {
    headers.forEach( function (key, index) {
      if (!unMarshalledArray[0].hasOwnProperty(key)) {
        unMarshalledArray[0][key] = null;
      }
    });
    console.log(Papa.unparse(unMarshalledArray));
    firstRun = false;
  } else {
    console.log(Papa.unparse(unMarshalledArray, {header: false}));
  }
  unMarshalledArray = [];

}

if ( program.describe ) describeTable( query );
else scanDynamoDB( query );