Angular2 router: how to correctly load children modules with their own routing rules

Question

here is my Angular2 app structure:

Here is part of my code. The following is the main module of the Angular2 app, that imports its routing rules and a child module (EdgeModule) and uses some components related to some pages.

app.module.ts

@NgModule({
    declarations: [
        AppComponent,
        PageNotFoundComponent,
        LoginComponent
    ],
    imports: [
        ...
        appRouting,
        EdgeModule
    ],
    providers: [
        appRoutingProviders,
        LoginService
    ],
    bootstrap: [AppComponent]
})

export class AppModule {
}

Here is the routing rules for the main module. It have paths to login page and page not found.

app.routing.ts

const appRoutes: Routes = [
    { path: 'login', component: LoginComponent },
    { path: '**', component: PageNotFoundComponent }
];

export const appRoutingProviders: any[] = [];

export const appRouting = RouterModule.forRoot(appRoutes, { useHash: true });

Here is EdgeModule that declares the component that it uses and import its own routing rules and 2 child modules (FirstSectionModule and SecondSectionModule).

edge.module.ts

@NgModule({
    declarations: [
        EdgeComponent,
        SidebarComponent,
        TopbarComponent
    ],
    imports: [
        ...
        edgeRouting,
        FirstSectionModule,
        SecondSectionModule
    ],
    providers: [
        AuthGuard
    ]
})

export class EdgeModule {
}

Here is the routing rules for the module that loads, as you can see, topbar and sidebar components.

edge.routing.ts

Paths['edgePaths'] = {
    firstSection: 'firstSection',
    secondSection: 'secondSection'
};

const appRoutes: Routes = [
    { path: '', component: EdgeComponent,
        canActivate: [AuthGuard],
        children: [
            { path: Paths.edgePaths.firstSection, loadChildren: '../somepath/first-section.module#FirstModule' },
            { path: Paths.edgePaths.secondSection, loadChildren: '../someotherpath/second-section.module#SecondModule' },
            { path: '', redirectTo: edgePaths.dashboard, pathMatch: 'full' }
        ]
    }
];

export const edgeRouting = RouterModule.forChild(appRoutes);

Finally, this is one of the two child module, that have its components and imports its routing rules.

first-section.module.ts

@NgModule({
    declarations: [
        FirstSectionComponent,
        SomeComponent
    ],
    imports: [
        ...
        firstSectionRouting
    ],
    providers: [
        AuthGuard,
    ]
})

export class FirstSectionModule {
}

These are the routing rules for the pages (components) of FirstSectionModule

first-section.routing.ts

Paths['firstSectionPaths'] = {
    someSubPage: 'some-sub-page',
    someOtherSubPage: 'some-other-sub-page'
};

const appRoutes: Routes = [
    {
        path: '',
        children: [
            { path: Paths.firstSectionPaths.someSubPage, component: someSubPageComponent},
            { path: Paths.firstSectionPaths.someOtherSubPage, component: someOtherSubPageComponent},
            { path: '', component: AnagraficheComponent }
        ]
    }
];

export const firstSectionRouting = RouterModule.forChild(appRoutes);

Almost the same happens for second-section.module.ts and second-section.routing.ts files.

When i run the app the first things that load is the page related to FirstSectionComponent, with no sidebar nor topbar.

Can you tell me what's wrong with my code? There are not errors in the console.

Answer 1

You can try this using loadChildren where the homeModule, productModule, aboutModule have their own route rules.

const routes: Routes = [
    { path: 'home', loadChildren: 'app/areas/home/home.module#homeModule' },
    { path: 'product', loadChildren: 'app/areas/product/product.module#ProductModule' },
    { path: 'drawing', loadChildren: 'app/areas/about/about.module#AboutModule' }
];

export const appRouting = RouterModule.forRoot(routes);

and the home route rules will be like

export const RouteConfig: Routes = [
    {
        path: '',
        component: HomeComponent,
        canActivate: [AuthGuard],
        children: [
            { path: '', component: HomePage },
            { path: 'test/:id', component: Testinfo},
            { path: 'test2/:id', component: Testinfo1},
            { path: 'test3/:id', component: Testinfo2}
        ]
    }
];

this is also known as lazy loading the modules.

{ path: 'lazy', loadChildren: 'lazy/lazy.module#LazyModule' }

There's a few important things to notice here: We use the property loadChildren instead of component. We pass a string instead of a symbol to avoid loading the module eagerly. We define not only the path to the module but the name of the class as well. There's nothing special about LazyModule other than it has its own routing and a component called LazyComponent.

Check out this awesome tutorial related to this: https://angular-2-training-book.rangle.io/handout/modules/lazy-loading-module.html

Answer 2

In your app.routing.ts, there are only 2 routes and no route included to navigate to the Main section (as in the diagram). There needs to be a route entry with loadchildren property so it will load the module for the Main section.

routes: Routes = [...
{ 
path: 'main', loadChildren: '<file path>/<Edge module file name>#EdgeModule' 
}
...];

This will load the rest of the modules, components routes and everything insite the EdgeModule.

Answer 3

Not sure if I get the problem correctly, but here is a small code snippet which I used to generate routes dynamically:

app.component.ts:

constructor(private _router: Router) {
}

ngOnInit() {
     ...
     this._router.config[0].children = myService.getRoutes(); 
     this._router.resetConfig(this._router.config);
     console.debug('Routes:', this._router.config);
     ...
}

It is not OOTB solution, but you can get information about current routes.

Answer 4

It's a dependency injection problem. We don't need to inject FirstSectionModule & SecondSectionModule in the edgeModule & about route we can use inside of FirstSectionModule & SecondSectionModule. So just removing it from edgeModule will work.

Answer 5

In Angular 13 & 13+ version, we can do like:-

const routes: Routes = [
  {
    path: "user",
    loadChildren: () => import("./user/user.module").then((m) => {m.UserModule})
  }
];