Flutter – Make an HTTP POST Request

In app development, the ability to fetch data from external sources, such as REST APIs, is a fundamental requirement. In Flutter, whether you need to send some data to the RESTful API, access a database, or then Send content from the Flutter App, Flutter provides you with the tools and packages(HTTP) to do this kind of API calls easily. Here we will explore how to interact with external data sources, Send JSON data(Key-Value pairs), and integrate it into your Flutter application.

Required Tools

To build this app, you need the following items installed on your machine:

• Visual Studio Code / Android Studio
• Android Emulator / iOS Simulator / Physical Device device.
• Flutter Installed
• Flutter plugin for VS Code / Android Studio.

About the API

This is a API link of HTTP POST Request

POST - https://jsonplaceholder.typicode.com/posts 

Step By Step Implementations

Step 1: Create a New Project in Android Studio

To set up Flutter Development on Android Studio please refer to Android Studio Setup for Flutter Development, and then create a new project in Android Studio please refer to Creating a Simple Application in Flutter.

Step 2: Add the dependency to our project

In the pubspec.yaml file we have to add the below dependency for the http package which provide varrious API call methods.

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^1.0.2
  http: ^1.1.0

Step 3: Import the Package

First of all import material.dart file.

import 'package:flutter/material.dart';

Step 4: Execute the main Method

Here the execution of our app starts.

Dart

void main() {
  runApp(MyApp());
}

Step 5: Create MyApp Class

In this class we are going to implement the MaterialApp , here we are also set the Theme of our App.

Dart

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.green, // Set the app's primary theme color
      ),
      home: APICall(),
    );
  }
}

Step 6: Create APICall Class

In this class we are going to make HTTP POST request to the API endpoint and Display the result that would received from the API (Sucess Status Code for this API call is 201).

Dart

class APICall extends StatefulWidget {
  @override
  _APICallState createState() => _APICallState();
}

class _APICallState extends State<APICall> {
  final String apiUrl = 'https://jsonplaceholder.typicode.com/posts';
  final TextEditingController nameController = TextEditingController();
  final TextEditingController emailController = TextEditingController();
  String result = ''; // To store the result from the API call

  @override
  void dispose() {
    nameController.dispose();
    emailController.dispose();
    super.dispose();
  }

  Future<void> _postData() async {
    try {
      final response = await http.post(
        Uri.parse(apiUrl),
        headers: <String, String>{
          'Content-Type': 'application/json; charset=UTF-8',
        },
        body: jsonEncode(<String, dynamic>{
          'name': nameController.text,
          'email': emailController.text,
          // Add any other data you want to send in the body
        }),
      );

      if (response.statusCode == 201) {
        // Successful POST request, handle the response here
        final responseData = jsonDecode(response.body);
        setState(() {
          result = 'ID: ${responseData['id']}\nName: ${responseData['name']}\nEmail: ${responseData['email']}';
        });
      } else {
        // If the server returns an error response, throw an exception
        throw Exception('Failed to post data');
      }
    } catch (e) {
      setState(() {
        result = 'Error: $e';
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('POST Request Example'),
      ),
      body: Padding(
        padding: EdgeInsets.all(16.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            TextField(
              controller: nameController,
              decoration: InputDecoration(labelText: 'Name'),
            ),
            TextField(
              controller: emailController,
              decoration: InputDecoration(labelText: 'Email'),
            ),
            ElevatedButton(
              onPressed: _postData,
              child: Text('Submit'),
            ),
            SizedBox(height: 20.0),
            Text(
              result,
              style: TextStyle(fontSize: 16.0),
            ),
          ],
        ),
      ),
    );
  }
}

Here is the full Code of main.dart file

Dart

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.green, // Set the app's primary theme color
      ),
      home: APICall(),
    );
  }
}

class APICall extends StatefulWidget {
  @override
  _APICallState createState() => _APICallState();
}

class _APICallState extends State<APICall> {
  final String apiUrl = 'https://jsonplaceholder.typicode.com/posts';
  final TextEditingController nameController = TextEditingController();
  final TextEditingController emailController = TextEditingController();
  String result = ''; // To store the result from the API call

  @override
  void dispose() {
    nameController.dispose();
    emailController.dispose();
    super.dispose();
  }

  Future<void> _postData() async {
    try {
      final response = await http.post(
        Uri.parse(apiUrl),
        headers: <String, String>{
          'Content-Type': 'application/json; charset=UTF-8',
        },
        body: jsonEncode(<String, dynamic>{
          'name': nameController.text,
          'email': emailController.text,
          // Add any other data you want to send in the body
        }),
      );

      if (response.statusCode == 201) {
        // Successful POST request, handle the response here
        final responseData = jsonDecode(response.body);
        setState(() {
          result = 'ID: ${responseData['id']}\nName: ${responseData['name']}\nEmail: ${responseData['email']}';
        });
      } else {
        // If the server returns an error response, throw an exception
        throw Exception('Failed to post data');
      }
    } catch (e) {
      setState(() {
        result = 'Error: $e';
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('POST Request Example'),
      ),
      body: Padding(
        padding: EdgeInsets.all(16.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            TextField(
              controller: nameController,
              decoration: InputDecoration(labelText: 'Name'),
            ),
            TextField(
              controller: emailController,
              decoration: InputDecoration(labelText: 'Email'),
            ),
            ElevatedButton(
              onPressed: _postData,
              child: Text('Submit'),
            ),
            SizedBox(height: 20.0),
            Text(
              result,
              style: TextStyle(fontSize: 16.0),
            ),
          ],
        ),
      ),
    );
  }
}

Output: