Routing & Navigating Pages in Angular 2
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Routing in Angular allows directing users to different pages/components based on their navigation choices. It defines routes for pages by creating components and linking them in the routes configuration. Components can link to routes using routerLink and navigate between them in code using the Router service. Route guards prevent navigation under certain conditions. Lazy loading allows splitting the app into smaller modules to improve performance. Code is cleaned up by exporting all imports from a single index file.
![Navigate from code
● Of course, You can navigate from page to another using code.
Let’s see How do we do that.
We will need to inject router in the constructor and call navigate
function.
export class TestComponent {constructor(private router:
Router) {}
back() {
this.router.navigate(['/']);}}](https://image.slidesharecdn.com/angular2-171117061817/85/Routing-Navigating-Pages-in-Angular-2-8-320.jpg)
Routing & Navigating Pages in Angular 2
- 1. Routing & Navigating Pages in Angular 2 By :- Deepak Mehra Software Consultant KNOLDUS SOFTWARE LLP By :- Deepak Mehra Software Consultant KNOLDUS SOFTWARE LLP
- 2. Agenda ● Why routing is necessary ● Define routes for pages ● Link to Routes ● Navigate from Code ● Route Guards ● Route Based Link Styling ● Lazy Loading ● Code Clean Up
- 3. Why routing is necessary? ● Routing helps in directing users to different pages based on the option they choose on the main page. Hence, based on the option they choose, the required Angular Component will be rendered to the user.
- 4. Define routes for pages ● Now, before you define routes for pages. Let’s see ● <base href> ● Most routing applications should add a <base> element to the index.html as the first child in the <head> tag to tell the router how to compose navigation URLs. ● ● Step 1 − Add the base reference tag in the index.html file. ● <html> ● <head><base href=”/”></head>
- 5. Define routes for pages ● Before we define define routes for the pages, Let’s create files for the pages. For example Let’s create Inventory.component.ts and Product.component.ts and write simple logic like below import {Component} from '@angular/core'; @Component ({ selector: 'app-root',template: '<h1>Inventory</h1>'}) export class InventoryComponent {}
- 6. Link to Routes ● The RouterLink directives on the anchor tags give the router control over those elements. The navigation paths are fixed, so you can assign a string to the routerLink (a "one-time" binding). That is how you navigate from one page to another <a routerLink="/product" routerLinkActive="active">Product</a>
- 7. Adding an error route ● We can also add an error route. In Routing, one can also add an error route. This can happen if the user goes to a page which does not exist in the application. Step1. Add a PageNotFound component as NotFound.component.ts. Step2. {path: '**', component: PageNotFoundComponent} ** is for any route which does not fit the default route. They will be directed to the PageNotFoundComponent component.
- 8. Navigate from code ● Of course, You can navigate from page to another using code. Let’s see How do we do that. We will need to inject router in the constructor and call navigate function. export class TestComponent {constructor(private router: Router) {} back() { this.router.navigate(['/']);}}
- 9. Route Guards ● Sometimes we want to prevent a user from going to a particular page or discourage them from leaving a page. That’s what route guards are designed for. Route guards have two properties 1. Can Activate 2.Can Deactivate
- 10. Route Guards 2. Can Deactivate We can use ‘Can deactivate’ to prevent a user from leaving a page. This is often helpful when a user is leaving the page before saving the data.
- 11. Route Based Linking Style ● If you have a header in your website and you want to highlight the currently active link then you can do that by using “routerLinkActive” Step1 . <li><a routerLink="/home" routerLinkActive="active">Home</a></li> Step2. Add css #nav-bar li > a.active { color: black;
- 12. Lazy Loading ● So far our app has only one module and that is app module. Let’s see how we can add multiple module. Our application can be broken down into smaller sections. We will add in a user module.
- 13. Code Cleanup ● In order to clean up the code, we can expose all of the imports inside the directory from a single index file and then we can just import it with a single import line. This is referred to as creating barrells. Step 1. Create an index file. Export * from ‘./test.component’ Step 2. In app module Import { } from ‘./index’
- 14. DEMO
- 16. Thank you