Update
Originally I wrote the answer here first, but I ended up writing a more detailed post later:
The full source code is there, too.
How to make HTTP requests in Flutter
This answer tells how to make HTTP requests using the http package by the Dart team. If more advanced functionality is needed, check out the Dio package mentioned in the comments.
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
final response = await get(Uri.parse('https://jsonplaceholder.typicode.com/posts'));
// sample info available in response
final statusCode = response.statusCode;
final headers = response.headers;
final contentType = headers['content-type'];
final 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
final url = Uri.parse('https://jsonplaceholder.typicode.com/posts');
final headers = {"Content-type": "application/json"};
final json = '{"title": "Hello", "body": "body text", "userId": 1}';
// make POST request
final response = await post(url, headers: headers, body: json);
// check the status code for the result
final statusCode = response.statusCode;
// this API passes back the id of the new item added to the body
final 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
final url = Uri.parse('https://jsonplaceholder.typicode.com/posts/1');
final headers = {"Content-type": "application/json"};
final json = '{"title": "Hello", "body": "body text", "userId": 1}';
// make PUT request
final response = await put(url, headers: headers, body: json);
// check the status code for the result
final statusCode = response.statusCode;
// this API passes back the updated item with the id added
final body = response.body;
// {
// "title": "Hello",
// "body": "body text",
// "userId": 1,
// "id": 1
// }
}
PATCH request
A PATCH request is meant to modify a existing resource.
_makePatchRequest() async {
// set up PATCH request arguments
final url = Uri.parse('https://jsonplaceholder.typicode.com/posts/1');
final headers = {"Content-type": "application/json"};
final json = '{"title": "Hello"}';
// make PATCH request
final response = await patch(url, headers: headers, body: json);
// check the status code for the result
final statusCode = response.statusCode;
// only the title is updated
final body = response.body;
// {
// "userId": 1,
// "id": 1
// "title": "Hello",
// "body": "quia et suscipit
suscipit recusandae... (old body text not changed)",
// }
}
Notice that the JSON string that is passed in only includes the title, not the other parts like in the PUT example.
DELETE request
_makeDeleteRequest() async {
// post 1
final url = Uri.parse('https://jsonplaceholder.typicode.com/posts/1');
// make DELETE request
final response = await delete(url);
// check the status code for the result
final statusCode = response.statusCode;
}
Authentication
Although the demo site we used above did not require it, if you need to include authentication headers, you can do it like this:
Basic Authentication
// import 'dart:convert'
final username = 'username';
final password = 'password';
final credentials = '$username:$password';
final stringToBase64Url = utf8.fuse(base64Url);
final encodedCredentials = stringToBase64Url.encode(credentials);
final headers = {
HttpHeaders.contentTypeHeader: "application/json", // or whatever
HttpHeaders.authorizationHeader: "Basic $encodedCredentials",
};
Bearer (token) Authentication
// import 'dart:io';
final token = 'WIiOiIxMjM0NTY3ODkwIiwibmFtZSI6Ikpv';
final headers = {
HttpHeaders.contentTypeHeader: "application/json", // or whatever
HttpHeaders.authorizationHeader: "Bearer $token",
};
Related
