Preview: AWS Amplify's new code-first DX (Gen 2)

The next generation of Amplify's backend building experience with a TypeScript-first DX.

Add authentication

The next feature you will be adding is authentication.

Authentication with Amplify

Amplify uses Amazon Cognito as its authentication provider. Amazon Cognito is a robust user directory service that handles user registration, authentication, account recovery & other operations. In this tutorial, you'll learn how to add authentication to your application using Amazon Cognito and username/password login.

Create authentication service

To add authentication to your app, run this command:

1amplify add auth

Select the defaults for the following prompts:

1? Do you want to use the default authentication and security configuration? Default configuration
2
3Warning: you will not be able to edit these selections.
4? How do you want users to be able to sign in? Username
5? Do you want to configure advanced settings? No, I am done.

To deploy the service, run the push command:

1amplify push
2
3✔ Are you sure you want to continue? (Y/n) · yes

Now, the authentication service has been deployed and you can start using it. To view the deployed services in your project at any time, go to Amplify Console by running the following command:

1amplify console

Now that you have your authentication service deployed to AWS, it's time to add authentication to your app. Creating a login flow can be quite difficult and time consuming to get right. Luckily, Amplify UI has an Authenticator component that provides an entire authentication flow for you, using the configuration you specified in amplifyconfiguration.json.

Install Amplify UI

The @aws-amplify/ui-react-native package includes React Native specific UI components you'll use to build your app. Install it with the following command:

1expo install @aws-amplify/ui-react-native react-native-safe-area-context

1npm install @aws-amplify/ui-react-native react-native-safe-area-context

You will also need to install the pod dependencies for iOS:

1npx pod-install

After installing pod dependencies, rebuild the app:

1npm run ios

Add the Amplify UI Authenticator component

Open App.js and make the following changes:

Open App.tsx and make the following changes:

Import the withAuthenticator Higher-Order Component and useAuthenticator hook:

1import {
2  withAuthenticator,
3  useAuthenticator
4} from '@aws-amplify/ui-react-native';

Create a custom SignOutButton component that will be used within the App component and only re-render when its user context changes. Destructure the user and signOut properties returned from the hook.

1// retrieves only the current value of 'user' from 'useAuthenticator'
2const userSelector = (context) => [context.user];
3
4const SignOutButton = () => {
5  const { user, signOut } = useAuthenticator(userSelector);
6  return (
7    <Pressable onPress={signOut} style={styles.buttonContainer}>
8      <Text style={styles.buttonText}>
9        Hello, {user.username}! Click here to sign out!
10      </Text>
11    </Pressable>
12  );
13};

Add the SignOutButton component to your App component inside of the containers you defined in the last section:

1// ...
2return (
3  <SafeAreaView style={styles.container}>
4    <View style={styles.container}>
5      <SignOutButton />
6    </View>
7  </SafeAreaView>
8);
9//...

Lastly, wrap your App export with the withAuthenticator Amplify UI component:

1export default withAuthenticator(App);

Run the app to see the new authentication flow protecting the app:

1npm start

Now you should see the app load with an authentication flow allowing users to sign up and sign in. Below you can find a full sample of the code:

1import React, { useEffect, useState } from 'react';
2import {
3  StyleSheet,
4  Text,
5  View,
6  TextInput,
7  Pressable,
8  SafeAreaView
9} from 'react-native';
10import { generateClient } from 'aws-amplify/api';
11import { createTodo } from './src/graphql/mutations';
12import { listTodos } from './src/graphql/queries';
13import {
14  withAuthenticator,
15  useAuthenticator
16} from '@aws-amplify/ui-react-native';
17
18import { Amplify } from 'aws-amplify';
19import config from './src/amplifyconfiguration.json';
20Amplify.configure(config);
21
22// retrieves only the current value of 'user' from 'useAuthenticator'
23const userSelector = (context) => [context.user];
24
25const SignOutButton = () => {
26  const { user, signOut } = useAuthenticator(userSelector);
27  return (
28    <Pressable onPress={signOut} style={styles.buttonContainer}>
29      <Text style={styles.buttonText}>
30        Hello, {user.username}! Click here to sign out!
31      </Text>
32    </Pressable>
33  );
34};
35
36const initialFormState = { name: '', description: '' };
37const client = generateClient();
38
39const App = () => {
40  const [formState, setFormState] = useState(initialFormState);
41  const [todos, setTodos] = useState([]);
42
43  useEffect(() => {
44    fetchTodos();
45  }, []);
46
47  function setInput(key, value) {
48    setFormState({ ...formState, [key]: value });
49  }
50
51  async function fetchTodos() {
52    try {
53      const todoData = await client.graphql({
54        query: listTodos
55      });
56      const todos = todoData.data.listTodos.items;
57      setTodos(todos);
58    } catch (err) {
59      console.log('error fetching todos');
60    }
61  }
62
63  async function addTodo() {
64    try {
65      if (!formState.name || !formState.description) return;
66      const todo = { ...formState };
67      setTodos([...todos, todo]);
68      setFormState(initialFormState);
69      await client.graphql({
70        query: createTodo,
71        variables: { input: todo }
72      });
73    } catch (err) {
74      console.log('error creating todo:', err);
75    }
76  }
77
78  return (
79    <SafeAreaView style={styles.container}>
80      <View style={styles.container}>
81        <SignOutButton />
82        <TextInput
83          onChangeText={(value) => setInput('name', value)}
84          style={styles.input}
85          value={formState.name}
86          placeholder="Name"
87        />
88        <TextInput
89          onChangeText={(value) => setInput('description', value)}
90          style={styles.input}
91          value={formState.description}
92          placeholder="Description"
93        />
94        <Pressable onPress={addTodo} style={styles.buttonContainer}>
95          <Text style={styles.buttonText}>Create todo</Text>
96        </Pressable>
97        {todos.map((todo, index) => (
98          <View key={todo.id ? todo.id : index} style={styles.todo}>
99            <Text style={styles.todoName}>{todo.name}</Text>
100            <Text style={styles.todoDescription}>{todo.description}</Text>
101          </View>
102        ))}
103      </View>
104    </SafeAreaView>
105  );
106};
107
108export default withAuthenticator(App);
109
110const styles = StyleSheet.create({
111  container: { width: 400, flex: 1, padding: 20, alignSelf: 'center' },
112  todo: { marginBottom: 15 },
113  input: {
114    backgroundColor: '#ddd',
115    marginBottom: 10,
116    padding: 8,
117    fontSize: 18
118  },
119  todoName: { fontSize: 20, fontWeight: 'bold' },
120  buttonContainer: {
121    alignSelf: 'center',
122    backgroundColor: 'black',
123    paddingHorizontal: 8
124  },
125  buttonText: { color: 'white', padding: 16, fontSize: 18 }
126});

1import React, { useEffect, useState } from 'react';
2import {
3  StyleSheet,
4  Text,
5  View,
6  TextInput,
7  Pressable,
8  SafeAreaView
9} from 'react-native';
10import { generateClient } from 'aws-amplify/api';
11import { createTodo } from './src/graphql/mutations';
12import { listTodos } from './src/graphql/queries';
13import {
14  withAuthenticator,
15  useAuthenticator
16} from '@aws-amplify/ui-react-native';
17
18// retrieves only the current value of 'user' from 'useAuthenticator'
19const userSelector = (context) => [context.user];
20
21const SignOutButton = () => {
22  const { user, signOut } = useAuthenticator(userSelector);
23  return (
24    <Pressable onPress={signOut} style={styles.buttonContainer}>
25      <Text style={styles.buttonText}>
26        Hello, {user.username}! Click here to sign out!
27      </Text>
28    </Pressable>
29  );
30};
31
32const initialFormState = { name: '', description: '' };
33const client = generateClient();
34
35const App = () => {
36  const [formState, setFormState] = useState(initialFormState);
37  const [todos, setTodos] = useState([]);
38
39  useEffect(() => {
40    fetchTodos();
41  }, []);
42
43  function setInput(key, value) {
44    setFormState({ ...formState, [key]: value });
45  }
46
47  async function fetchTodos() {
48    try {
49      const todoData = await client.graphql({
50        query: listTodos
51      });
52      const todos = todoData.data.listTodos.items;
53      setTodos(todos);
54    } catch (err) {
55      console.log('error fetching todos');
56    }
57  }
58
59  async function addTodo() {
60    try {
61      if (!formState.name || !formState.description) return;
62      const todo = { ...formState };
63      setTodos([...todos, todo]);
64      setFormState(initialFormState);
65      await client.graphql({
66        query: createTodo,
67        variables: { input: todo }
68      });
69    } catch (err) {
70      console.log('error creating todo:', err);
71    }
72  }
73
74  return (
75    <SafeAreaView style={styles.container}>
76      <View style={styles.container}>
77        <SignOutButton />
78        <TextInput
79          onChangeText={(value) => setInput('name', value)}
80          style={styles.input}
81          value={formState.name}
82          placeholder="Name"
83        />
84        <TextInput
85          onChangeText={(value) => setInput('description', value)}
86          style={styles.input}
87          value={formState.description}
88          placeholder="Description"
89        />
90        <Pressable onPress={addTodo} style={styles.buttonContainer}>
91          <Text style={styles.buttonText}>Create todo</Text>
92        </Pressable>
93        {todos.map((todo, index) => (
94          <View key={todo.id ? todo.id : index} style={styles.todo}>
95            <Text style={styles.todoName}>{todo.name}</Text>
96            <Text style={styles.todoDescription}>{todo.description}</Text>
97          </View>
98        ))}
99      </View>
100    </SafeAreaView>
101  );
102};
103
104export default withAuthenticator(App);
105
106const styles = StyleSheet.create({
107  container: { width: 400, flex: 1, padding: 20, alignSelf: 'center' },
108  todo: { marginBottom: 15 },
109  input: {
110    backgroundColor: '#ddd',
111    marginBottom: 10,
112    padding: 8,
113    fontSize: 18
114  },
115  todoName: { fontSize: 20, fontWeight: 'bold' },
116  buttonContainer: {
117    alignSelf: 'center',
118    backgroundColor: 'black',
119    paddingHorizontal: 8
120  },
121  buttonText: { color: 'white', padding: 16, fontSize: 18 }
122});

Using Amplify UI connected components makes it easier to manage styling across your entire app.

In this example, you used the Amplify UI library and the withAuthenticator Higher-Order Component to quickly get up and running with a real-world authentication flow. You can also customize this component to add or remove fields, update styling, or other configurations. You can even override function calls if needed. To learn more, visit the Amplify UI documentation website.

In addition to withAuthenticator, you can build custom authentication flows with the Amplify Library for JS. Amplify's Auth package has several methods including signUp, signIn, forgotPassword, and signOut that allow you full control over all aspects of the user authentication flow.

Connect API and database to the app

Next steps

Add authentication

Authentication with Amplify

Create authentication service

Create login UI

Install Amplify UI

Add the Amplify UI Authenticator component