AsyncStorage in React Native to Store Data in Session

React Native AsyncStorage

This is an Example to Store Data in Session Using AsyncStorage in React Native. React Native AsyncStorage can be used to manage sessions.

If you want the user to log in once and don’t want to log in again when the user opens the app after some time then, you have to store any variable in the app which can be checked and according to that, we will show the screen.

For example, once we login we can store the user id in the AsyncStorage to remember the user and when we open the app again we check for the user id, If it is there in the AsyncStorage then we can directly send the user to the next screen without login else we will show the Login Screen. This process is called session management using AsyncStorage.

AsyncStorage can only be used to store small values in the form of a key and value pair because it has some limitations to store the data. You can store your value with respect to any key and then can access the value using the key again. It works perfectly on both platforms (Android and IOS).

Under the Lean Core Project AsyncStorage has been moved to its new home @react-native-community/async-storage after the launch of React Native 0.59. If you are using React Native >= 0.59 then please follow the instruction for React Native >= 0.59.

To Import AsyncStorage in Code

import AsyncStorage from '@react-native-community/async-storage'

Store the value in AsyncStorage

AsyncStorage.setItem('any_key_here', this.state.textInputData);

Get the value from the AsyncStorage

AsyncStorage.getItem('any_key_here').then(value =>
    //AsyncStorage returns a promise so adding a callback to get the value
    this.setState({ getValue: value })
    //Setting the value in Text
);

In this Example. We will see the use of AsyncStorage by storing some value and after that, we will retrieve the value from the same key. So let’s get started.

To Make a React Native App

Getting started with React Native will help you to know more about the way you can make a React Native project. We are going to use react-native init to make our React Native App. Assuming that you have node installed, you can use npm to install the react-native-cli command line utility. Open the terminal and go to the workspace and run

npm install -g react-native-cli

Run the following commands to create a new React Native project

react-native init ProjectName

If you want to start a new project with a specific React Native version, you can use the --version argument:

react-native init ProjectName --version X.XX.X
react-native init ProjectName --version react-native@next

This will make a project structure with an index file named App.js in your project directory.

Installation of Dependency

To use AsyncStorage we need to install @react-native-community/async-storage dependency.

To install this open the terminal and jump into your project using

cd ProjectName

Run the following command to install

npm install @react-native-community/async-storage --save

This command will copy all the dependency into your node_module directory. –save is optional, it is just to update the @react-native-community/async-storage dependency in your package.json file.

CocoaPods Installation

After the updation of React Native 0.60, they have introduced autolinking so we do not require to link the library but need to install pods. So to install pods use

cd ios && pod install && cd ..

Code

Now, Open App.js in any code editor and replace the code with the following code

App.js

//This is an example code to understand AsyncStorage// 
import React, { Component } from 'react';
//import react in our code. 

import AsyncStorage from '@react-native-community/async-storage'
import { StyleSheet, View, TextInput, Button, Alert, Text, TouchableOpacity } from 'react-native';

export default class App extends Component {
  constructor() {
    super();
    this.state = {
      textInputData: '',
      //to get the value from the TextInput
      getValue: '',
      //to set the value on Text
    };
  }
  saveValueFunction = () => {
    //function to save the value in AsyncStorage
    if(this.state.textInputData){
      //To check the input not empty
      AsyncStorage.setItem('any_key_here', this.state.textInputData);
      //Setting a data to a AsyncStorage with respect to a key 
      this.setState({ textInputData: '' })
      //Resetting the TextInput
      alert('Data Saved');
      //alert to confirm
    }else{
      alert('Please fill data');
      //alert for the empty InputText
    }
  };
  getValueFunction = () => {
    //function to get the value from AsyncStorage
    AsyncStorage.getItem('any_key_here').then(value =>
      //AsyncStorage returns a promise so adding a callback to get the value
      this.setState({ getValue: value })
      //Setting the value in Text 
    );
  };
  render() {
    return (
      <View style={styles.MainContainer}>
        <TextInput
          placeholder="Enter Some Text here"
          value={this.state.textInputData}
          onChangeText={data => this.setState({ textInputData: data })}
          underlineColorAndroid="transparent"
          style={styles.TextInputStyle}
        />
        <TouchableOpacity
          onPress={this.saveValueFunction}
          style={styles.button}>
          <Text style={styles.buttonText}> SAVE VALUE </Text>
        </TouchableOpacity>
        <TouchableOpacity
          onPress={this.getValueFunction}
          style={styles.button}>
          <Text style={styles.buttonText}> GET VALUE </Text>
        </TouchableOpacity>
        <Text style={styles.text}> {this.state.getValue} </Text>
      </View>
    );
  }
}
const styles = StyleSheet.create({
  MainContainer: {
    alignItems: 'center',
    flex: 1,
    margin: 10,
    marginTop:60
  },
  TextInputStyle: {
    textAlign: 'center',
    height: 40,
    width: '100%',
    borderWidth: 1,
    borderColor: '#808000',
  },
  button: {
    width: '100%',
    height: 40,
    padding: 10,
    backgroundColor: '#808000',
    marginTop: 10,
  },
  buttonText: {
    color: '#fff',
    textAlign: 'center',
  },
  text: {
    fontSize: 20,
    textAlign: 'center',
  },
});

To Run the React Native App

Open the terminal again and jump into your project using.
cd ProjectName
To run the project on an Android Virtual Device or on real debugging device
react-native run-android
or on the iOS Simulator by running
react-native run-ios (macOS only).

Output Screenshots

Android

IOS

       

Output in Online Emulator

That was the React Native AsyncStorage. If you have any doubts or you want to share something about the topic you can comment below or contact us here. The remaining components will be covered in the next article. Stay tuned!

Hope you liked it. 🙂

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