How to assign default values for routing parameters in angular.dart?

问题

Consider the following route config:

route
    ..addRoute(
      name: 'custom',
      defaultRoute: true,
      path: '/:param1/:param2',
      enter: view('view/template.html')
    );

I am injecting the router into a controller and setting up router.onRouteStart.listen, within which I am accessing parameters via router.activePath.last.parameters, now, if param2 is not present in the user entered route, then i want to assign a default value to param2 (also replace the route). How do I go about it?

回答1:

After a bit more of exploration found this sample on angular.dart.tutorial: https://github.com/angular/angular.dart.tutorial/blob/master/Chapter_06/lib/routing/recipe_book_router.dart#L19-L24

Which has the following way of doing it (changes according to my sample code):

route
    ..addRoute(
        name: 'default',
        defaultRoute: true,
        path: '/:param1',
        enter: (RouteEnterEvent e) => 
            router.go('custom', {
                    'param1': router.activePath.last.parameters['param1'],
                    'param2': 'defaultValue'},
                //[Optional, if mounted in a nested route]  
                //startingFrom: router.root.findRoute('custom_head'),
                replace: true))
    ..addRoute(
        name: 'custom',
        defaultRoute: true,
        path: '/:param1/:param2',
        enter: view('view/template.html')
    );

If the user doesn't provide a value for param2 then the first route gets activated, which will assign a default value for param2 and force update of url by replacing earlier one.

来源：https://stackoverflow.com/questions/22871434/how-to-assign-default-values-for-routing-parameters-in-angular-dart