What are the HTTP Request In Flutter ?

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A composable, Future-based library for making HTTP requests.  It is easy to retrieve and upload JSON via a REST-based web service. So in this article, we will go through What are the HTTP Request In Flutter?

What is the HTTP Request In Flutter?

We will be using JSONPlaceholder as a target for our API examples below.

GET     /posts
GET     /posts/1
GET     /posts/1/comments
GET     /comments?postId=1
GET     /posts?userId=1
POST    /posts
PUT     /posts/1
PATCH   /posts/1
DELETE  /posts/1

Setup

Add the HTTP package dependency in pubspec.yaml.

dependencies:
  http: ^0.12.0+1

GET requests

_makeGetRequest() async {

  // make request
  Response response = await get('https://jsonplaceholder.typicode.com/posts');

  // sample info available in response
  int statusCode = response.statusCode;
  Map<String, String> headers = response.headers;
  String contentType = headers['content-type'];
  String json = response.body;

  // TODO convert json to object...

}

Replace /posts with /posts/1 and the other GET requests mentioned above. Using posts returns an array of JSON objects while /posts/1 returns a single JSON object. You can use dart: convert to convert the raw JSON string to objects.

POST request

_makePostRequest() async {

  // set up POST request arguments
  String url = 'https://jsonplaceholder.typicode.com/posts';
  Map<String, String> headers = {"Content-type": "application/json"};
  String json = '{"title": "Hello", "body": "body text", "userId": 1}';

  // make POST request
  Response response = await post(url, headers: headers, body: json);

  // check the status code for the result
  int statusCode = response.statusCode;

  // this API passes back the id of the new item added to the body
  String body = response.body;
  // {
  //   "title": "Hello",
  //   "body": "body text",
  //   "userId": 1,
  //   "id": 101
  // }

}

PUT request

A PUT request is meant to replace a resource or create it if it doesn’t exist.

_makePutRequest() async {

  // set up PUT request arguments
  String url = 'https://jsonplaceholder.typicode.com/posts/1';
  Map<String, String> headers = {"Content-type": "application/json"};
  String json = '{"title": "Hello", "body": "body text", "userId": 1}';

  // make PUT request
  Response response = await put(url, headers: headers, body: json);

  // check the status code for the result
  int statusCode = response.statusCode;

  // this API passes back the updated item with the id added
  String body = response.body;
  // {
  //   "title": "Hello",
  //   "body": "body text",
  //   "userId": 1,
  //   "id": 1
  // }

}

PATCH request

A PATCH request is meant to modify an existing resource.

_makePatchRequest() async {

  // set up PATCH request arguments
  String url = 'https://jsonplaceholder.typicode.com/posts/1';
  Map<String, String> headers = {"Content-type": "application/json"};
  String json = '{"title": "Hello"}';

  // make PATCH request
  Response response = await patch(url, headers: headers, body: json);

  // check the status code for the result
  int statusCode = response.statusCode;

  // only the title is updated
  String body = response.body;
  // {
  //   "userId": 1,
  //   "id": 1
  //   "title": "Hello",
  //   "body": "quia et suscipit\nsuscipit recusandae... (old body text not changed)",
  // }

}

DELETE request

_makeDeleteRequest() async {

  // post 1
  String url = 'https://jsonplaceholder.typicode.com/posts/1';

  // make DELETE request
  Response response = await delete(url);

  // check the status code for the result
  int statusCode = response.statusCode;

}

Authentication

// import 'dart:convert'

final username = 'username';
final password = 'password';
final credentials = '$username:$password';
final stringToBase64Url = utf8.fuse(base64Url);
final encodedCredentials = stringToBase64Url.encode(credentials);

Map<String, String> headers = {
  HttpHeaders.contentTypeHeader: "application/json", // or whatever
  HttpHeaders.authorizationHeader: "Basic $encodedCredentials",
};

Bearer (token) Authentication

// import 'dart:io';

final token = 'WIiOiIxMjM0NTY3ODkwIiwibmFtZSI6Ikpv';

Map<String, String> headers = {
  HttpHeaders.contentTypeHeader: "application/json", // or whatever
  HttpHeaders.authorizationHeader: "Bearer $token",
};

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Written by Abhishek Dhanani

Abhishek Dhanani, a skilled software developer with 3+ years of experience, masters Dart, JavaScript, TypeScript, and frameworks like Flutter and NodeJS. Proficient in MySQL, Firebase, and cloud platforms AWS and GCP, he delivers innovative digital solutions.