Tuesday, 1 November 2016

Routing concepts in Angular2

In this post we are going to see how to configure the routing in Angular2 applications, in previous versions we are used the ngRoute and UiRouter concepts to configure the Route, it is almost similar to that , but we are using here the Module system to configure the Routes.

import { Routes, RouterModule } from '@angular/router';


const routes: Routes = [
  { path: 'rating', component: webformComponent },
  { path: 'news',component:NewsComponent},
  { path: '', component:webformComponent },
  { path: '**', component:UnknownComponent }
];


export const routedComponents = [AppComponent, webformComponent,
     NewsComponent,PrintComponent,UnknownComponent];


@NgModule({
  imports : [CommonModule,RouterModule.forRoot(routes)],
  declarations:routedComponents,
  exports: [RouterModule,EditorModule,CommonModule],
})

export class AppRoutingModule { }


From the above code you can see that the RouterModule and Routes are used to configure the Routes.

We have to give the path and component which have to load for that url, here you can see the RouterModule.forRoot is used to load the routes , in overall applications we should have only one root route, others are must be child, because it is defines that is already defines and creates, so we dont need to create again and again, Here you can see the path is given as empty that means default routing, another one you can see is '**' that specifies the path whatever may be other than configured is routed to unknown component., Now this is the root component for Router module which is stored in separate file, so we have to configure or add this to main module, so we are configure the RouterModule to be exports , then only it can be import or can be used in another module.


Now we will define another set of routing which is separate from this , in this sample we are configuring and separating the routes based on module.


  import { NgModule } from '@angular/core';
  import { CommonModule} from '@angular/common'
  import { FormsModule } from '@angular/forms';
  import { Routes, RouterModule } from '@angular/router';
  import { EmployeeComponent,StudentComponent } from './employee.component'
  import { EmployeeDetailComponent } from './employee.detail'
  import { EmployeeDetailGuard } from './employeeDetailGuard';
  import { EmployeeResolver } from './employeeDetailResolve'
  import { EmployeeFilterPipe } from './employeePipe'

  const routes: Routes = [ 
    { path: 'employee',component:EmployeeComponent},
    { path: 'employee/:id',component:EmployeeDetailComponent, 
                canActivate:[EmployeeDetailGuard],
                resolve:{ userinfo:EmployeeResolver }},
    { path: 'student',component:StudentComponent},  
  ];

  export const routedComponents = [EmployeeComponent,StudentComponent,
  EmployeeDetailComponent,EmployeeFilterPipe];

  @NgModule({
    imports : [CommonModule,FormsModule, RouterModule.forChild(routes)],
    declarations:routedComponents,
    providers:[EmployeeDetailGuard,EmployeeResolver],
    exports: [RouterModule,FormsModule],
  })

  export class UserRoutingModule { }


Now we have to import both the module system in the main module which loads the application, in the above sample you can see the route is configure as ForChild, this is because we have to configure the routes as Root for only one time,
Finally we are going to import the both the things in Main module, in the above code you can see the CanActivate and Resolve properties in routes , we will discuss about this things in later posts.

import { NgModule } from '@angular/core';
    import { BrowserModule } from '@angular/platform-browser';
    import { FormsModule } from '@angular/forms';
    import { HttpModule } from '@angular/http';
        
    import { FocusedDirective } from './directives/onload.directive';
    import { FocusOnLoadDirective,RgMultilineEllipses } from './directives/onload.directive';
    import { FormComponent } from './Forms/form.component';
    import { BaseRequestOptions, Http, Headers } from '@angular/http';
    import { webformComponent } from './Component/web.component'
    
    import { AppLoadComponent } from './app.load.component'

    
    import { DataService } from './data.service';
    import { AppRoutingModule } from './app.routing.module'
    import { UserRoutingModule } from './user.routing.module';
  
    @NgModule({
        imports: [BrowserModule,HttpModule,UserRoutingModule,AppRoutingModule],
        exports: [],
        declarations: [AppLoadComponent,FormComponent,FocusedDirective,
                 RgMultilineEllipses],
        providers:[DataService],
        bootstrap:[AppLoadComponent]
    })
    export class AppModule { 

    }


In the module you can see that the both the Router module are imported, Main module loads the both the routes because the router module is exported in both modules,Now we will see how to configure the router links and containers


<div>
    <nav class="navbar navbar-fixed-top navbar-inverse">
        <div class="container-fluid">
            <div class="navbar-header">   
                
                <button type="button" class="navbar-toggle collapsed" 
                      data-toggle="collapse" 
                    data-target="#angular-collapse-menu" 
                    aria-expanded="false">
                    <span class="sr-only">Toggle Navigation</span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                    <span class="icon-bar"></span>
                </button>
                                             
                <a class="navbar-brand" href="#">Angular 2</a>
            </div>
            <div class="collapse navbar-collapse" id="angular-collapse-menu">
                <ul class="nav navbar-nav">                    
                        <li>
                            <a [routerLink]="['/employee']">Employees</a>
                        </li>
                        <li>
                            <a [routerLink]="['/student']">Student</a>
                        </li>
                        <li>
                            <a [routerLink]="['/rating']">Rating</a>
                        </li>
                        <li>
                            <a [routerLink]="['/news']">News</a>  
                        </li>
                    </ul>
            </div>
            
        </div>                        
    </nav>    
</div>
<div style="padding-top:65px;">
    <router-outlet></router-outlet>
</div>



that's it everything is configured, [routerLink]="['/news']"  is used to create a router link which will call the path /news and NewsComponent instance is created,  <router-outlet> </router-outlet>  is used to inject the view in the container we will load the applications, Let we see the output.


























From this post you can see how to configure the Routes and RoutesModule for the Angular2 Applications.





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