Now we are going to add an API that returns a list of all the notes a user has.

Add the Function

Create a new file called list.js with the following.

import * as dynamoDbLib from './libs/dynamodb-lib';
import { success, failure } from './libs/response-lib';

export async function main(event, context, callback) {
  const params = {
    TableName: 'notes',
    // 'KeyConditionExpression' defines the condition for the query
    // - 'userId = :userId': only return items with matching 'userId' partition key
    // 'ExpressionAttributeValues' defines the value in the condition
    // - ':userId': defines 'userId' to be Identity Pool identity id of the authenticated user
    KeyConditionExpression: "userId = :userId",
    ExpressionAttributeValues: {
      ":userId": event.requestContext.identity.cognitoIdentityId,

  try {
    const result = await'query', params);
    // Return the matching list of items in response body
    callback(null, success(result.Items));
  catch(e) {
    callback(null, failure({status: false}));

This is pretty much the same as our get.js except we only pass in the userId in the DynamoDB query call.

Configure the API Endpoint

Open the serverless.yml file and append the following.

    # Defines an HTTP API endpoint that calls the main function in list.js
    # - path: url path is /notes
    # - method: GET request
    handler: list.main
      - http:
          path: notes
          method: get
          cors: true
          authorizer: aws_iam

This defines the /notes endpoint that takes a GET request.


Create a mocks/list-event.json file and add the following.

  "requestContext": {
    "identity": {
      "cognitoIdentityId": "USER-SUB-1234"

And invoke our function from the root directory of the project.

$ serverless webpack invoke --function list --path mocks/list-event.json

The response should look similar to this.

  statusCode: 200,
  headers: {
    'Access-Control-Allow-Origin': '*',
    'Access-Control-Allow-Credentials': true
  body: '[{"attachment":"hello.jpg","content":"hello world","createdAt":1487800950620,"noteId":"578eb840-f70f-11e6-9d1a-1359b3b22944","userId":"USER-SUB-1234"}]'

Note that this API returns an array of note objects as opposed to the get.js function that returns just a single note object.

Next we are going to add an API to update a note.