hierarchical route | Better definition and usage of routes in an AngularJS

hierarchical-route

hierarchical-route

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Created by Adelino Rodrigues

bower install angular-hierarchical-route

Demo Download GitHub

angular-hierarchical-route

This module complements ngRoute and is of particular benefit when the routes of your application have a hierarchical structure.

This project includes two sample applications which do exactly the same thing (read the about section!) ... but are implemented differently:

  • The /with-route-only sample application (access live demo!) uses ngRoute and nothing else
  • The /with-helper sample application (access live demo!) uses ngRoute in conjunction with angular-hierarchical-route to implement a more advanced routing behavior. Please note that this sample could also be implemented with plain ngRoute with some trade-offs.

You can also run the sample applications on your local machine

Background

Routing allows a developer to break an application into smaller and more manageable chunks. ngRoute with its ng-view directive and $routeProvider allows to partition an application into several top level templates and controllers, hence helping dealing with the complexity.

Routing provides two additional benefits for the end user (and for the developer who is testing repeatedly his development):

  • Allows to use the browser's Back button to return back to a previous state of the application

  • Allows to book mark the application in a certain state and return to it directly. This is also known as deep linking.

Why did this module come to exist?

When a view in an ng-view is itself like a mini-application

Typically one route (or more), in an application, have significant functionality. In the sample, all views are trivial but the #/home plays the role of the complex portion in the application.

Some options:

  • If possible, have the complex route as the application and the rest as static pages. This approach cannot be applied when other paths require dynamic behavior (for instance the #/admin in the sample)

  • Create a big directive for the complex route to make it into a sort of mini-application. I personally tried this approach and ended-up with a big blob module not very understandable.

  • Using routing. With experience this is what best fits with the AngularJS way of working. As side benefits you enable the back button and allow to deep linking within the application (for instance the #/home/FR/2988507/forecast in the sample)

How to use it?

Registering simple routes

Routes for which you do not require sub-states, can be registered with ngRoute's $routeProvider:

$routeProvider.when('/admin', {templateUrl: '../common/admin/admin.html', controller: 'AdminCityCtrl'});

When needing sub-states for a view in ng-view

This is when you create a hierarchy of routes. To create a hierachical route with the hierarchyProvider:

hierarchyProvider.add({
    rootPath: '/home',
    templateUrl: 'home/home.html',
    controller: 'HomeCtrl'})

... then you need to add all the callable paths within that hierarchy (including the root path). For every path you can associate a logical name:

.callableFrom('/home','home')
    .resolve({
        countries: annotatedFnCountries
    })
.callableFrom('/home/:countryId','country')
    .resolve({
        countries: annotatedFnCountries,
        cities: annotatedFnCities
    })

... and conclude by registering that hierarchy of routes using the $routeProvider:

.registerWith($routeProvider);

Promises to resolve

As shown above you can define for every path a map of promises to resolve. This map of resolved objects will be injected in the controller as an object named resolved:

.controller('HomeCtrl', ['$scope', 'weatherService', 'resolved', 'constants', 'routeCalled',
                         function($scope, weatherService, resolved, constants, routeCalled) {
    //Set loaded data in scope
    $scope.countries = resolved.countries;
    $scope.cities = resolved.cities;

Constants

Constants can be attached to a callable path. They will then be injected under the name constants (see controller definition above).

In the sample application, this is used to define the view name of a nested view:

.callableFrom('/home/:countryId/:cityId/forecast','forecast')
    .resolve({
        // ...
    })
    .constants({weatherView: 'home/forecast-weather.html'})

This view is then made visible to view by the controller:

$scope.weatherView = constants.weatherView;

... and finally included using the ng-include directive:

<div class="col-xs-6" ng-show="cityId" ng-include="weatherView">
</div>

Injection of route context

Another object can be injected in the controller under the name routeCalled which represents the route context:

  • this will include the angular route services as properties: routeCalled.$location, routeCalled.$route and routeCalled.$routeParams
  • it provides you with a way to find out weather a route is active based on its logical name: routeCalled.isActive('forecast')
  • a few goTo options (as detailed in Navigation section below)

Navigation

Simple Go to

This is achieved by invoking the routeCalled.goTo function:

routeCalled.goTo('forecast', {countryId: $scope.countryId, cityId: $scope.cityId});

Go to first route which accepts the provided parameters

This function allows to find a path, not by its name, but by the signature of its parameters:

routeCalled.goToFirstWith({countryId: newId});

Update current parameters or move on to next

When a user input bound to a path parameter changes, the routeCalled.updateOrGoToFirstWith function becomes very useful. Typically a parameter changes either because it was undefined and now is set, or, because its value was updated.

When going from blank to a value, this corresponds to a move further down in the route. It is otherwise an update of the current route parameters:

routeCalled.updateOrGoToFirstWith({countryId: $scope.countryId, cityId: newId});

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