Implementation

• Create a GraphQL API and database

  a. Add a GraphQL API to your app by running the the following command from the root of your app directory:
  

  amplify add api
  
  ? Please select from one of the below mentioned services: GraphQL
  ? Provide API name: notesapp
  ? Choose the default authorization type for the API: API Key
  ? Enter a description for the API key: demo
  ? After how many days from now the API key should expire: 7 (or your preferred expiration)
  ? Do you want to configure advanced settings for the GraphQL API: No, I am done.
  ? Do you have an annotated GraphQL schema?  No
  ? Do you want a guided schema creation?  Yes
  ? What best describes your project: Single object with fields
  ? Do you want to edit the schema now? Yes

  b. Open the GraphQL schema in your text editor: amplify/backend/api/myapi/schema.graphql.

  Update the file with the following schema:
  

  type Note @model {
    id: ID!
    name: String!
    description: String
  }
  

  c. Save the file. Then go back to the command line and hit enter to complete the API configuration step.

• Deploy the API

  Now that the API has been configured locally it is time to deploy it. To do so, run the Amplify push command:
  

  amplify push --y

  This will do 3 things:

  1. Create the AppSync API
  2. Create a DynamoDB table
  3. Create the local GraphQL operations in a folder located at src/graphql that you can use to query the API

  To view the GraphQL API in your account at any time, run the following command:

  amplify console api
  
  > Choose GraphQL
  

  To view the Amplify app in your account at any time, run the following command:
  

  amplify console

• Write front-end code to interact with the API

  Now that the back end has been deployed, let's write some code to allow users to create, list, and delete notes.

  Update src/App.js with the following code:

  import React, { useState, useEffect } from 'react';
  import './App.css';
  import { API } from 'aws-amplify';
  import { withAuthenticator, AmplifySignOut } from '@aws-amplify/ui-react';
  import { listNotes } from './graphql/queries';
  import { createNote as createNoteMutation, deleteNote as deleteNoteMutation } from './graphql/mutations';
  
  const initialFormState = { name: '', description: '' }
  
  function App() {
    const [notes, setNotes] = useState([]);
    const [formData, setFormData] = useState(initialFormState);
  
    useEffect(() => {
      fetchNotes();
    }, []);
  
    async function fetchNotes() {
      const apiData = await API.graphql({ query: listNotes });
      setNotes(apiData.data.listNotes.items);
    }
  
    async function createNote() {
      if (!formData.name || !formData.description) return;
      await API.graphql({ query: createNoteMutation, variables: { input: formData } });
      setNotes([ ...notes, formData ]);
      setFormData(initialFormState);
    }
  
    async function deleteNote({ id }) {
      const newNotesArray = notes.filter(note => note.id !== id);
      setNotes(newNotesArray);
      await API.graphql({ query: deleteNoteMutation, variables: { input: { id } }});
    }
  
    return (
      <div className="App">
        <h1>My Notes App</h1>
        <input
          onChange={e => setFormData({ ...formData, 'name': e.target.value})}
          placeholder="Note name"
          value={formData.name}
        />
        <input
          onChange={e => setFormData({ ...formData, 'description': e.target.value})}
          placeholder="Note description"
          value={formData.description}
        />
        <button onClick={createNote}>Create Note</button>
        <div style={{marginBottom: 30}}>
          {
            notes.map(note => (
              <div key={note.id || note.name}>
                <h2>{note.name}</h2>
                <p>{note.description}</p>
                <button onClick={() => deleteNote(note)}>Delete note</button>
              </div>
            ))
          }
        </div>
        <AmplifySignOut />
      </div>
    );
  }
  
  export default withAuthenticator(App);
  

  There are 3 main functions in our app:

  1. fetchNotes - This function uses the API class to send a query to the GraphQL API and retrieve a list of notes.
  2. createNote - This function also uses the API class to send a mutation to the GraphQL API, the main difference is that in this function we are passing in the variables needed for a GraphQL mutation so that we can create a new note with the form data.
  3. deleteNote - Like createNote, this function is sending a GraphQL mutation along with some variables, but instead of creating a note we are deleting a note.
• Run the app

  To test out the app, run the start command:
  

  npm start