dio
- Dart course
- Advanced
- Lesson 35/83
- 5 min
Learn the advanced HTTP client with dio.
The dio package
dio is a more powerful HTTP client than the http package. It offers interceptors, timeouts, automatic JSON parsing, cancelable requests and FormData support.
Usage: create a client with var dio = Dio();. var r = await dio.get('https://api.example.com/users');. r.data is automatically parsed JSON (a Map or List).
dio is preferred over http in larger projects because of its interceptor chain and advanced configuration.
Configuration with BaseOptions
Dio(BaseOptions(baseUrl: 'https://api.example.com', connectTimeout: Duration(seconds: 5))) configures the client. baseUrl is prefixed to all requests.
So dio.get('/users') hits https://api.example.com/users. Timeouts are set separately for connection and reading.
Interceptors are added with dio.interceptors.add(...); used for logging, retry, auth token injection. This layered design gives power in large projects.
Practice Configure Dio with BaseOptions
Add import 'package:dio/dio.dart';. Inside main add var dio = Dio(BaseOptions(baseUrl: 'https://api.example.com'));. Add print(dio.options.baseUrl);.
Starter code
void main() {
// add dio import; set baseUrl via BaseOptions; print baseUrl
}Sample solution
import 'package:dio/dio.dart';
void main() {
var dio = Dio(BaseOptions(baseUrl: 'https://api.example.com'));
print(dio.options.baseUrl);
}Expected output
https://api.example.com
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Dio client
var dio = ____();var dio = Dio();Explanation: Dio() creates a new dio client.
2 Match the dio features
| Term | Meaning |
|---|---|
BaseOptions |
Configuration |
interceptors |
Request chain |
data |
Auto JSON |
cancelToken |
Request cancellation |
3 What does dio do automatically?
- Starts a new Isolate
- Opens a database
- Parses the JSON body Correct answer
- Draws UI
Explanation: dio parses the JSON body automatically (r.data is a Map/List).