Example of Infinite Loading Listview in React Native using FlatList

Paging in ListView

This is an Example of Infinite Loading Listview in React Native using FlatList. A React Native list view that supports infinite scroll. In mobile application development, ListView has a very important part as we use ListView in almost all applications. If we have to load a huge amount of data in a listview we have to use pagination for the seamless performance. A ListView with Load More Button in the bottom to load data can be an option but what if we load the data automatically when the user reaches the end of the list? This feature will give a good user experience to your application users.

What is pagination?

Let’s take a case where you can simply imagine what if Facebook loads all the Facebook posts from the Facebook database on your Facebook wall? Doesn’t it sound nasty? It will take hundreds of hours even more than that so what is the best way to load the data? Simply paging. When you open the Facebook they just show you 10-20 post and while you scroll the Facebook they load the next 10-20 posts in background. That is what the paging is.

In our example,

1. We are loading the first 10 posts from the web API call in componentDidMount.
2. While the user reaches the bottom of the list we call the Web API again to get the next 10 posts.

We are using a variable offset to manage the index on upcoming Data. We will increase the offset by 1 after the successful call of the web API so that when we call the web API next time we will get the next data-set. So let’s get started with the example.

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.

Code for Infinite Loading Listview

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

App.js

//This is an example of React Native
//Pagination to Load More Data dynamically - Infinite List
import React, { Component } from 'react';
//import react in our code.
import {
  View,
  Text,
  StyleSheet,
  FlatList,
  ActivityIndicator
} from 'react-native';
//import all the components we are going to use.

export default class App extends Component {
  constructor() {
    super();
    this.state = {
      loading: false,
      isListEnd: false,
      //Loading state used while loading the data for the first time
      serverData: [],
      //Data Source for the FlatList
      fetching_from_server: false,
      //Loading state used while loading more data
    };
    this.offset = 1;
    //Index of the offset to load from web API
  }
  componentDidMount() {
    this.loadMoreData();
  }
  loadMoreData = () => {
    if (!this.state.fetching_from_server && !this.state.isListEnd) {
      //On click of Load More button We will call the web API again
      this.setState({ fetching_from_server: true }, () => {
        fetch('https://aboutreact.herokuapp.com/getpost.php?offset=' + this.offset)
          //Sending the currect offset with get request
          .then(response => response.json())
          .then(responseJson => {
            if (responseJson.results.length > 0) {
              //Successful response from the API Call
              this.offset = this.offset + 1;
              //After the response increasing the offset for the next API call.
              this.setState({
                serverData: [...this.state.serverData, ...responseJson.results],
                //adding the new data with old one available
                fetching_from_server: false,
                //updating the loading state to false
              });
            } else {
              this.setState({
                fetching_from_server: false,
                isListEnd: true,
              });
            }
          })
          .catch(error => {
            console.error(error);
          });
      });
    }
  };
  renderFooter() {
    return (
      <View style={styles.footer}>
        {this.state.fetching_from_server ? (
          <ActivityIndicator color="black" style={{ margin: 15 }} />
        ) : null}
      </View>
    );
  }
  render() {
    return (
      <View style={styles.container}>
        {this.state.loading ? (
          <ActivityIndicator size="large" />
        ) : (
          <FlatList
            style={{ width: '100%' }}
            keyExtractor={(item, index) => index.toString()}
            data={this.state.serverData}
            onEndReached={() => this.loadMoreData()}
            onEndReachedThreshold={0.5}
            renderItem={({ item, index }) => (
              <View style={styles.item}>
                <Text style={styles.text}>
                  {item.id}
                  {'.'}
                  {item.title.toUpperCase()}
                </Text>
              </View>
            )}
            ItemSeparatorComponent={() => <View style={styles.separator} />}
            ListFooterComponent={this.renderFooter.bind(this)}
            //Adding Load More button as footer component
          />
        )}
      </View>
    );
  }
}
const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    paddingTop: 30,
  },
  item: {
    padding: 10,
  },
  separator: {
    height: 0.5,
    backgroundColor: 'rgba(0,0,0,0.4)',
  },
  text: {
    fontSize: 15,
    color: 'black',
  },
  footer: {
    padding: 10,
    justifyContent: 'center',
    alignItems: 'center',
    flexDirection: 'row',
  },
});

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

Output in Online Emulator

That was the example of Infinite Loading Listview in React Native. If you have any doubts or you want to share something about the topic you can comment below or contact us here. There will be more posts coming soon. Stay tuned!

Hope you liked it. 🙂