How to Call a REST API in Flutter: http/dio and JSON
Mapping JSON to Dart objects
To fetch server data in Flutter, use the http (lightweight) or dio (feature-rich) package.
Convert JSON responses to Dart classes using the fromJson()/toJson() pattern, which can be auto-generated with json_serializable + build_runner.
Manage loading/error/success states with FutureBuilder or state management libraries (Riverpod's FutureProvider, etc.).
Implementation Steps
1
Add http or dio package + define API model classes
2
Write fromJson()/toJson() methods (or use json_serializable)
3
Separate API call logic with Repository pattern
4
Implement async UI with FutureBuilder or Riverpod FutureProvider
Pros
- ✓ dio allows centralized token refresh/error handling with interceptors
- ✓ Auto-generate serialization code with json_serializable
Cons
- ✗ build_runner code generation can be slow in large projects
- ✗ Confusion without pre-designed error handling strategy
Use Cases
Loading SNS feed list
E-commerce product search and detail view