react native-tutorial

React Native HTTP

You must send an HTTP request each time your application connects to the backend server (to get or upload data). Here, we’ll demonstrate how to use React Native to accomplish network activities.

Code Snippet of Basic Network Call using Fetch

fetch('Web URL HERE', {
    method: 'GET'
    //Request Type 
})
.then((response) => response.json())
//If response is in json then in success
.then((responseJson) => {
    //Success 
    console.log(responseJson);
})
//If response is not in json then in error
.catch((error) => {
    //Error 
    console.error(error);
});


In the example below, we are using free demo APIs. The example has two-button each has its own onPress which triggers our services. Just for the demo purpose, we are using buttons to trigger the request but If You need any data which needs to render while loading your screen you can use componentDidMount lifecycle method to load the data from the server as soon as the component is mounted. 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.

Code

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

App.js

import React from 'react';
import {
  SafeAreaView,
  StyleSheet,
  View,
  TouchableOpacity,
  Text,
} from 'react-native';

const App = () => {
  const getDataUsingGet = () => {
    //GET request
    fetch('https://jsonplaceholder.typicode.com/posts/1', {
      method: 'GET',
      //Request Type
    })
      .then((response) => response.json())
      //If response is in json then in success
      .then((responseJson) => {
        //Success
        alert(JSON.stringify(responseJson));
        console.log(responseJson);
      })
      //If response is not in json then in error
      .catch((error) => {
        //Error
        alert(JSON.stringify(error));
        console.error(error);
      });
  };

  const getDataUsingPost = () => {
    //POST json
    var dataToSend = {title: 'foo', body: 'bar', userId: 1};
    //making data to send on server
    var formBody = [];
    for (var key in dataToSend) {
      var encodedKey = encodeURIComponent(key);
      var encodedValue = encodeURIComponent(dataToSend[key]);
      formBody.push(encodedKey + '=' + encodedValue);
    }
    formBody = formBody.join('&');
    //POST request
    fetch('https://jsonplaceholder.typicode.com/posts', {
      method: 'POST', //Request Type
      body: formBody, //post body
      headers: {
        //Header Defination
        'Content-Type': 
          'application/x-www-form-urlencoded;charset=UTF-8',
      },
    })
      .then((response) => response.json())
      //If response is in json then in success
      .then((responseJson) => {
        alert(JSON.stringify(responseJson));
        console.log(responseJson);
      })
      //If response is not in json then in error
      .catch((error) => {
        alert(JSON.stringify(error));
        console.error(error);
      });
  };

  return (
    <SafeAreaView style={{flex: 1}}>
      <View style={styles.container}>
        <View style={styles.container}>
          {/*Running GET Request*/}
          <TouchableOpacity
            style={styles.buttonStyle}
            onPress={getDataUsingGet}>
            <Text style={styles.textStyle}>
              Get Data Using GET
            </Text>
          </TouchableOpacity>
          {/*Running POST Request*/}
          <TouchableOpacity
            style={styles.buttonStyle}
            onPress={getDataUsingPost}>
            <Text style={styles.textStyle}>
              Get Data Using POST
            </Text>
          </TouchableOpacity>
        </View>
        <Text
          style={{
            fontSize: 18,
            textAlign: 'center',
            color: 'grey'
          }}>
          React Native Fetch
        </Text>
        <Text
          style={{
            fontSize: 16,
            textAlign: 'center',
            color: 'grey'
          }}>
          www.aboutreact.com
        </Text>
      </View>
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: 'white',
    justifyContent: 'center',
    padding: 20,
  },
  textStyle: {
    fontSize: 18,
    color: 'white',
  },
  buttonStyle: {
    alignItems: 'center',
    backgroundColor: '#f4511e',
    padding: 10,
    marginVertical: 10,
  },
});

export default App;

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 (macOS only)


react-native run-ios

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