AWS Amplify Appsync React Notes

Link to the course

structure & goal of the course

  • Fundamentals of Appsync & Amplify
  • (Optional) Fundamentals of GraphQL - this is basically a course within a course, especially useful if you’re new-ish to GraphQL
  • Build a Frontend app using our Appsync backend API

What is AppSync

  • The glue that sits between all the AWS services & client apps. The facilitator.
  • nice to have: mermaid diagram to illsutrate the how the pieces play together

Benefits of using it

  • fast setup, & scale as needed
  • real-time subscriptions (“for a real time driven application”) & offline access
  • unified secured access
  • as many data sources as we want

What is amplify

  • a library/framework that helps developers quickly configure, manage, & create apps with features for AWS cloud
  • Has a CLI we can use for all this
    • the same things you can do with appsync console, you can also do with amplify cli, with a guided CLI flow.
  • has many modules we can use to speed up development:
    • Auth
    • Storage
    • API - how to expose your data, via rest API or GraphQL
    • Caching
    • UI components and more

Useful docs

Don’t you just love some helpful documentation?

Wed 16 March 2022

  • Made Appsync API using AWS console

the resolver is the entity between the schema, & the datasource.

  • worth remembering that you can use multiple AWS datasources with Appsync.
  • App sync resolvers make use of Velocity Template Language (VTL) - just an FYI, not that it’s been learnt in this course:)
  • Used Amplify CLI to create A GraphQL api (accessible via AppSync), that makes use of DynamoDB.

Thur 17 March 2022

  • Query data in Nextjs app using an Amplify generated Graphql query, and API imported from Amplify
import { API } from "aws-amplify"
import { listPosts } from "../src/graphql/queries.ts"

async function fetchPosts() {
const postData = await API.graphql({
    query: listPosts,


This is how easy it is to get data into your app when you use Amplify:)

Auth with Cognito

amplify add auth
  • Updated the API to have Public & Private access, using Cognito user pool for auth.
amplify update api
  • What our schema now looks like, with the auth (@auth(...)) directive specifying that an owner has full access to Posts, and the publiccan onlyread`.
type Post @model 
  rules: [
    {allow: owner, ownerField: "username"},
    {allow: public, operations: [read]}
  id: ID!
  title: String!
  content: String!
  username: String 
  coverImage: String

Saving images with S3

amplify add storage
amplify add hosting

Mock API

In order to quickly test and debug without pushing all changes in your project to the cloud, Amplify supports Local Mocking and Testing for certain categories including API (AWS AppSync), Storage (Amazon DynamoDB and Amazon S3), and Functions (AWS Lambda).

  • Big big time saver:)

AppSync subsciptions

  • Some real time goodness. Be weary of this as it is expensive on memory. don’t use it where it’s not necessary
  • docs - what does amplify datastore version of this look like?
type Subscription {
  newOnCreatePost: Post @aws_subscribe(mutations: ["createPost"])
  #newOnUpdatedPost: Post @aws_subscribe(mutations: ["updatePost"])