Router
- Dart course
- Advanced
- Lesson 28/83
- 5 min
Learn routing with shelf_router.
shelf_router
shelf_router is a package that maps URL paths to handlers. You create a Router() and add routes with .add('/path', handler).
There is also an annotation-based API: methods marked with @Route.get('/hello') are wired automatically via Router<MyApi>().add. This works through code generation (source_gen).
A Router is a handler: var handler = Router()..get('/hello', helloHandler);. You can pass this handler to shelf_io.
Multiple routers with Cascade
A Cascade tries multiple handlers; the first successful (200-level) response wins. A handler that returns 404 is skipped and the next is tried.
Usage: var handler = Cascade().add(apiRouter).add(staticHandler).handler;. The API is tried first; if no match, the static file handler.
This is a common pattern for REST API + static file serving.
Practice Add a route with Router
Add import 'package:shelf/shelf.dart'; import 'package:shelf_router/shelf_router.dart';. Define Response helloHandler(Request r) => Response.ok('merhaba');. Make main async; add var router = Router()..get('/hello', helloHandler);, var resp = await router(Request('GET', Uri.parse('http://localhost/hello'))); and print(await resp.readAsString());.
Starter code
void main() {
// add shelf and shelf_router imports; define helloHandler
// build Router with /hello route; call; print body
}Sample solution
import 'package:shelf/shelf.dart';
import 'package:shelf_router/shelf_router.dart';
Response helloHandler(Request r) => Response.ok('merhaba');
void main() async {
var router = Router()..get('/hello', helloHandler);
var resp = await router(Request('GET', Uri.parse('http://localhost/hello')));
print(await resp.readAsString());
}Expected output
merhaba
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does a Router do?
- Manages a database
- Does logging
- Produces JSON
- Maps URL paths to handlers Correct answer
Explanation: a router maps URL paths to handlers.
2 Match the Router methods
| Term | Meaning |
|---|---|
.get('/path', h) |
GET route |
.post('/path', h) |
POST route |
.add('/path', h) |
Manual add |
@Route.get |
Annotation |
3 Add a GET route
router.____('/hello', helloHandler);router.get('/hello', helloHandler);Explanation: router.get('/hello', handler) adds a GET route.