TestLambda.js

'use strict';

const AWS = require("aws-sdk");	
const errors = require("./Errors.js");	

const findUserByEmailAddress = function(emailAddress)
{
 	AWS.config.dynamodb = { endpoint: "http://localhost:8000" };
 	const docClient = new AWS.DynamoDB.DocumentClient();
 
	 const query =
	 {
		 TableName: "TestTable",
		 Key:
		 {
			 emailAddress: emailAddress
		 }
	 };
 
	 return docClient.get(query).promise(function(err, data)
	 {
		if (err)
			reject(err);
		else
			resolve(data.Item);
	 });
}

const addUser = function(emailAddress)
{
	const newItem =
	{
		TableName: "TestTable",
		Item:
		{
			version: 0,
			emailAddress : emailAddress,
			info: {}
		}
	}

	return new Promise(function(resolve, reject) 
	{
		AWS.config.dynamodb = { endpoint: "http://localhost:8000" };		
		const docClient = new AWS.DynamoDB.DocumentClient();

		docClient.put(newItem).promise()
		.then(() => resolve(newItem.Item))
		.catch(err => reject(err))
	});
}

const updateUserInfo = function(user, info)
{
	const currentVersion = user.version;
	const updatedVersion = currentVersion + 1;

	const updateRequest =
	{
		TableName: "TestTable",
		Key: { emailAddress: user.emailAddress },		
		ReturnValues: "ALL_NEW",
		UpdateExpression: "SET info = :info, version=:updatedVersion",
		ConditionExpression: "version = :currenVersion",
		ExpressionAttributeValues :
		{
			":currenVersion": currentVersion,
			":updatedVersion": updatedVersion,
			":info": info
		}		
	}

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

	return new Promise(function(resolve, reject)
	{
		docClient.update(updateRequest).promise()
		.then(updateRequest => resolve(updateRequest.Attributes))
		.catch(err => reject(err));
	});
}

const isValidVersion = function(event) 
{
	return event.rpcVersion === 1 || false;
}

const updateOrAddUser = function(request)
{
	if (isValidVersion(request) === false)
	{
		return Promise.reject({ Error: -1 });
	}
	
	return new Promise(function(resolve, reject)
	{
		findUserByEmailAddress(request.emailAddress)
		.then(user =>
		{
			if (JSON.stringify(user) === "{}")
				return addUser(request.emailAddress);
			else
				return user;
		})
		.then(function(user)
		{
			return updateUserInfo(user, request.info);
		})
		.then(updatedUser => resolve(updatedUser))
		.catch(function(err)
		{
			reject(err);
		})
	});
}

exports.handler = (event, context, callback) => 
{
    console.log('Received event:', JSON.stringify(event, null, 2));

	updateOrAddUser(event)
	.then(function(user)
	{
		console.log("RESULT:", user);
		callback(null, user);
	})
	.catch(function(err)
	{
		callback(JSON.stringify(err));
	});
};

exports._test =
{
	findUserByEmailAddress: findUserByEmailAddress,
	addUser: addUser,
	updateUserInfo: updateUserInfo,
	updateOrAddUser: updateOrAddUser	
}