AWS DynamoDB simple scan/put operations

handler.js

// leads/read.read
'use_strict';

const uuid = require('uuid');
const AWS = require('aws-sdk');
const IsEmail = require('isemail');

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

module.exports.create = function(event, context, callback) {
	var timestamp = new Date().getTime();

	var data,
		error;

	if (event.body === null){
		// request body does not exist
		error = "missing_request_body";
	} else{
		// parse event body
		data = JSON.parse(event.body);

		// check for errors in request body
		if (typeof data.name !== "string" || typeof data.email !== "string"){
			// name/email missing
			error = "invalid_parameter";
		} else if (data.name == "" || data.email == ""){
			// name/email blank
			error = "blank_parameter";
		}else if (!IsEmail.validate(data.email)){
			// invalid email
			error = "invalid_email";
		}
	}

	if (error){
		return callback(null, {
			statusCode: 400,
			headers: { 'Content-Type':'text/plain' },
			body: error
		});
	}


	// valid name & email, continue...

	const scanParams = {
		TableName: process.env.DYNAMODB_TABLE,
		FilterExpression: '#email = :email',
		ExpressionAttributeNames: {
			'#email': 'email'
		},
		ExpressionAttributeValues: {
			':email': data.email
		}
	};

	dynamoDb.scan(scanParams, (error, scanData)=>{
		if (error){
			console.error(error);
			return callback(null, {
				statusCode: 500,
				headers: { 'Content-Type': 'text/plain' },
				body: "database_error"
			});
		}

		if (scanData.Count > 0){
			return callback(null, {
				statusCode: 400,
				headers: { 'Content-Type': 'text/plain' },
				body: "email_exists"
			});
		}

		// email doesn't yet exist... save lead
		const putParams = {
			TableName: process.env.DYNAMODB_TABLE,
			Item: {
				id: uuid.v1(),
				name: data.name,
				email: data.email,
				createdAt: timestamp
			}
		};

		// write lead to database
		dynamoDb.put(putParams, (error)=>{
			if (error){
				console.error(error);
				return callback(null, {
					statusCode: error.statusCode || 501,
					headers: { 'Content-Type':'text/plain' },
					body: "leads service CREATE failed."
				});
			}

			// SUCCESS!
			return callback(null, {
				statusCode: 200,
				headers: { 'Content-Type':'text/plain' },
				body: "success"
			});

		});

	});

};