dio

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.

Exercise 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);.

Show example solution

import 'package:dio/dio.dart';

void main() {
  var dio = Dio(BaseOptions(baseUrl: 'https://api.example.com'));
  print(dio.options.baseUrl);
}

Test yourself

Dio client
```
var dio = ____();
```
Show answer
```
var dio = Dio();
```
Match the dio features

BaseOptions

Configuration
interceptors

Request chain
data

Auto JSON
cancelToken

Request cancellation
What does dio do automatically?
- Starts a new Isolate
- Opens a database
- Parses the JSON body
- Draws UI
Show answer

Parses the JSON body — dio parses the JSON body automatically (r.data is a Map/List).

Next lesson: Summary - HTTP

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