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This is part 2 of Building a To-Do List App.
In this step, we’re creating a simple to do app (in React) and integrating it with Auth0.

​
Create React app

Let’s start by creating a React app using the create-react-app command. 
npx create-react-app todo-react-app
To verify navigate to the folder, start the dev server, and visit http://localhost:3000. 
cd todo-react-app
npm start

​
Install dependencies

Now, let’s install the various dependencies that we will need in the app. 
npm install todomvc-app-css classnames graphql-tag history react-router-dom

​
Setup Apollo Client

Let’s start with installing the Apollo dependencies and then create a setup. 
npm install @apollo/react-hooks apollo-cache-inmemory apollo-client apollo-link-http graphql apollo-link-context react-todomvc @auth0/auth0-react
Now, let’s update our src/App.js with the below content to include the Apollo client setup. 
import React from "react"

import ApolloClient from "apollo-client"
import { InMemoryCache } from "apollo-cache-inmemory"
import { ApolloProvider } from "@apollo/react-hooks"
import { createHttpLink } from "apollo-link-http"

import "./App.css"

const createApolloClient = () => {
  const httpLink = createHttpLink({
    uri: "http://localhost:8080/graphql",
    options: {
      reconnect: true,
    },
  })

  return new ApolloClient({
    link: httpLink,
    cache: new InMemoryCache(),
  })
}

const App = () => {
  const client = createApolloClient()
  return (
    <ApolloProvider client={client}>
      <div>
        <h1>todos</h1>
        <input
          className="new-todo"
          placeholder="What needs to be done?"
          autoFocus={true}
        />
      </div>
    </ApolloProvider>
  )
}

export default App
Here we have created a simple instance of the Apollo client and passed the URL of our GraphQL API. Then we have passed the client to ApolloProvider and wrapped our App so that its accessible throughout the app.

​
Queries and Mutations

Now, let’s add some queries and mutations. First, let’s see how we can add a todo and get todos. Create a file src/GraphQLData.js and add the following. 
import gql from "graphql-tag"

export const GET_TODOS = gql`
  query {
    queryTodo: queryTask {
      id
      value: title
      completed
    }
  }
`

export const ADD_TODO = gql`
  mutation addTask($task: AddTaskInput!) {
    addTask(input: [$task]) {
      task {
        id
        value: title
        completed
      }
    }
  }
`
Now, let’s see how to use this to add a todo. Let’s import the dependencies first in src/App.js replacing all the code. Let’s now create the functions to add a todo and get todos. 
import { useQuery, useMutation } from "@apollo/react-hooks"
import { Todos } from "react-todomvc"
import "react-todomvc/dist/todomvc.css"
import { useAuth0 } from "@auth0/auth0-react"
import { GET_TODOS, ADD_TODO } from "./GraphQLData"

function App() {
  const [add] = useMutation(ADD_TODO)

  const { user, isAuthenticated, loginWithRedirect, logout } = useAuth0()

  const { loading, error, data } = useQuery(GET_TODOS)
  if (loading) return <p>Loading</p>
  if (error) {
    return <p>`Error: ${error.message}`</p>
  }

  const addNewTodo = (title) =>
    add({
      variables: {
        task: {
          title: title,
          completed: false,
          user: { username: user.email },
        },
      },
      refetchQueries: [
        {
          query: GET_TODOS,
        },
      ],
    })

  return (
    <div>
      <Todos
        todos={data.queryTodo}
        addNewTodo={addNewTodo}
        todosTitle="Todos"
      />
    </div>
  )
}

export default App

​
Auth0 Integration

Now, let’s integrate Auth0 in our app and use that to add the logged-in user. Let’s first create an app in Auth0.
  • Head over to Auth0 and create an account. Click ‘sign up’ here
  • Once the signup is done, click “Create Application” in “Integrate Auth0 into your app”.
  • Give your app a name and select “Single Page Web App” app type
  • Select React as the technology
  • No need to do the sample app, scroll down to “Configure Auth0” and select “Application Settings”.
  • Select your app and add the values of domain and clientid in the file src/auth_template.json. Check this link for more information.
  • Add http://localhost:3000 to “Allowed Callback URLs”, “Allowed Web Origins” and “Allowed Logout URLs”.
Now that we have prepared our src/App.js file let’s update our src/index.js file with the following code. 
import React from "react"
import ReactDOM from "react-dom"
import App from "./App"
import {
  ApolloClient,
  ApolloProvider,
  InMemoryCache,
  createHttpLink,
} from "@apollo/client"
import { setContext } from "@apollo/client/link/context"
import { Auth0Provider, useAuth0 } from "@auth0/auth0-react"
import config from "./auth_template.json"

const GRAPHQL_ENDPOINT = "http://localhost:8080/graphql"

const AuthorizedApolloProvider = ({ children }) => {
  const { isAuthenticated, getIdTokenClaims } = useAuth0()
  const httpLink = createHttpLink({
    uri: GRAPHQL_ENDPOINT,
  })

  const authLink = setContext(async (_, { headers }) => {
    if (!isAuthenticated) {
      return headers
    }

    const token = await getIdTokenClaims()

    return {
      headers: {
        ...headers,
        "X-Auth-Token": token ? token.__raw : "",
      },
    }
  })

  const apolloClient = new ApolloClient({
    link: authLink.concat(httpLink),
    cache: new InMemoryCache(),
  })

  return <ApolloProvider client={apolloClient}>{children}</ApolloProvider>
}

ReactDOM.render(
  <Auth0Provider
    domain={config.domain}
    clientId={config.clientId}
    redirectUri={window.location.origin}
  >
    <AuthorizedApolloProvider>
      <React.StrictMode>
        <App />
      </React.StrictMode>
    </AuthorizedApolloProvider>
  </Auth0Provider>,
  document.getElementById("root"),
)
Note that for the app to work from this point on, the src/auth_template.json file must be configured with your auth0 credentials. Here is a reference Here Let’s also add definitions for updating, deleting and clearing all tasks to src/GraphQLData.js. Let’s also add the constants user, isAuthenticated, loginWithRedirect and logout which they receive from the variable useAuth0. We also create a constant called logInOut that contains the logic to know if the user is logged in or not. This variable will show a button to login or logout depending on the status of logged in or logged out. Note that before calling the component Todos we call our variable {logInOut} so that our login button appears above the app. 
import React from "react"
import { useQuery, useMutation } from "@apollo/client"
import { Todos } from "react-todomvc"

import "react-todomvc/dist/todomvc.css"
import { useAuth0 } from "@auth0/auth0-react"
import {
  GET_TODOS,
  ADD_TODO,
  UPDATE_TODO,
  DELETE_TODO,
  CLEAR_COMPLETED_TODOS,
} from "./GraphQLData"

function App() {
  const [add] = useMutation(ADD_TODO)
  const [del] = useMutation(DELETE_TODO)
  const [upd] = useMutation(UPDATE_TODO)
  const [clear] = useMutation(CLEAR_COMPLETED_TODOS)

  const { user, isAuthenticated, loginWithRedirect, logout } = useAuth0()

  const { loading, error, data } = useQuery(GET_TODOS)
  if (loading) return <p>Loading</p>
  if (error) {
    return <p>`Error: ${error.message}`</p>
  }

  const addNewTodo = (title) =>
    add({
      variables: {
        task: {
          title: title,
          completed: false,
          user: { username: user.email },
        },
      },
      refetchQueries: [
        {
          query: GET_TODOS,
        },
      ],
    })

  const updateTodo = (modifiedTask) =>
    upd({
      variables: {
        id: modifiedTask.id,
        task: {
          value: modifiedTask.title,
          completed: modifiedTask.completed,
        },
      },
      update(cache, { data }) {
        data.updateTask.task.map((t) =>
          cache.modify({
            id: cache.identify(t),
            fields: {
              title: () => t.title,
              completed: () => t.completed,
            },
          }),
        )
      },
    })

  const deleteTodo = (id) =>
    del({
      variables: { id },
      update(cache, { data }) {
        data.deleteTask.task.map((t) => cache.evict({ id: cache.identify(t) }))
      },
    })

  const clearCompletedTodos = () =>
    clear({
      update(cache, { data }) {
        data.deleteTask.task.map((t) => cache.evict({ id: cache.identify(t) }))
      },
    })

  const logInOut = !isAuthenticated ? (
    <p>
      <a href="#" onClick={loginWithRedirect}>
        Log in
      </a>
      to use the app.
    </p>
  ) : (
    <p>
      <a
        href="#"
        onClick={() => {
          logout({ returnTo: window.location.origin })
        }}
      >
        Log out
      </a>
      once you are finished, {user.email}.
    </p>
  )

  return (
    <div>
      {logInOut}
      <Todos
        todos={data.queryTodo}
        addNewTodo={addNewTodo}
        updateTodo={updateTodo}
        deleteTodo={deleteTodo}
        clearCompletedTodos={clearCompletedTodos}
        todosTitle="Todos"
      />
    </div>
  )
}

export default App
For our app to work correctly we need to update the src/GraphQLData.js file with the remaining queries. 
import gql from "graphql-tag"

export const GET_TODOS = gql`
  query {
    queryTodo: queryTask {
      id
      value: title
      completed
    }
  }
`

export const ADD_TODO = gql`
  mutation addTask($task: AddTaskInput!) {
    addTask(input: [$task]) {
      task {
        id
        value: title
        completed
      }
    }
  }
`

export const UPDATE_TODO = gql`
  mutation updateTask($id: ID!, $task: TaskPatch!) {
    updateTask(input: { filter: { id: [$id] }, set: $task }) {
      task {
        id
        value: title
        completed
      }
    }
  }
`

export const DELETE_TODO = gql`
  mutation deleteTask($id: ID!) {
    deleteTask(filter: { id: [$id] }) {
      task {
        id
      }
    }
  }
`

export const CLEAR_COMPLETED_TODOS = gql`
  mutation updateTask {
    deleteTask(filter: { completed: true }) {
      task {
        id
      }
    }
  }
`
Here is the complete code Here Let’s now start the app. 
npm start
Now you should have an app running!