GraphQL with React and Hasura workshop

Independent consultant

Web / Mobile / VR / AR / IoT / AI

GDE, author, dev advocate @hasura.io

What is GraphQL

GraphQL

A query language for your API

What's wrong with REST

Restful API

The core idea in REST is to have a URL for every resource

RESTfull API problems

Description of resource is coupled to implementation

Overfetching

Underfetching

chaining requests to server to get needed data

So how does GraphQL solve it

Avoid over-fetching

Prevent multipe API calls

Lesser communication with API developers

Self-documenting

How it looks like

GraphQL SDL

type Post {

   title: String!

   content: String!

   user: User!

}

type Person {

    name: String!

    address: String

    posts: [Post!]!

}

GraphQL SDL

GraphQL Resolvers

Let's talk about GraphQL query language

First assignment

  • Fetch last 5 todos
  • Find your own user id by name
  • Fetch user with specific id
  • Insert a new todo
  • Update todo

Tip: If you are not sure with how to write GraphQL syntax use Explorer feature

Get Started

1_getting-to-know-graphql

Writing your own server

yarn add apollo-server graphql
const { ApolloServer, gql } = require('apollo-server')

const posts = [{
  id: 1,
  title: "Some title",
  description: "Description",
  userId: 1
}]

const users = [{
  id: 1,
  name: "Vladimir Novick",
  email: "12312@asdfa.com"
}]

const typeDefs = gql`
  type Post {
    id: ID!
    title: String!
    description: String!
    user: User
  }
  type User {
    id: ID!
    name: String!
    email: String
  }
  type Query {
    posts: [Post]
    users: [User]
  }
  type Mutation {
    addPost(post: PostInputType): Post
  }
    
  input PostInputType {
    userId: ID!
    title: String!
    content: String!
  }
`

const resolvers = {
  Query: {
    posts: () => posts.map(post => {
        const user = users.find(user => user.id === post.userId)
        return {
          id: post.id,
          title: post.title,
          description: post.description,
          user
        }
    }),
    users: () => users
  },
  Mutation: {
    addPost: (_, { post: {userId, title, content}}) => {
      const user = users.filter(user => user.id === userId).reduce((acc, u) => u, {})
      const postToPublish = {
        id: posts.reverse()[0].id + 1,
        title,
        description: content,
        userId: user.id
      }

      posts.push(postToPublish)
      return postToPublish
    }
  }
}

const server = new ApolloServer({
  typeDefs,
  resolvers
})

server.listen().then(({ url }) => console.log(url));

What about the client?

yarn add @apollo/react-hooks

passing variables to mutation

passing different options such as refetchQueries etc

3_graphql_client

Step 2

What about Architecture

Microservices architecture 

3factor.app Architecture

How do you start with backend?

  • Code your own
  • Use Hasura 
  • Use AWS AppSync

What is Hasura

open source and free engine that gives you auto-generates real-time GraphQL API on top of new or existing Postgres database

Features

  • Can be deployed to any cloud or run locally
  • Compatible with all Authentication solutions
  • Can run on top of new or existing Postgres database
  • Supports Postgres addons (PostGIS, TimescaleDB)
  • Auto-generates GraphQL api
  • GraphQL queries are compiled to performant SQL statements using native Postgres features

Features

  • Comes with hasura-cli which has awesome tools like migrations and more
  • Can work with custom SQL statements
  • Has configurable access controls for data
  • Can be connected to your own GraphQL server (does schema stitching)
  • Has eventing system which enables to trigger serverless functions

Let's see it in action

  • Go to hasura.io

  • Click on Get started with Heroku

  • Click on

  • Enter your app name

  • Click on deploy button

  • Click on View app

  • Create posts table

  • create users table

  • connect posts and users using foreign key and relationships

  • Add a remote schema

  • Change your code sandbox from Excercise 2 to connect to your newly created blog api

Excercise

Create custom business logic

Let's build todo app from scratch

 

Thank You

  @VladimirNovick

GraphQL workshop

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GraphQL workshop

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