Using routerLink to make result tabs as links

Using routerLink to make result tabs as links

In Susper, it was required that different result sections i.e All, Images,Videos and News should behave as links. Links provide us an advantage of opening the different result tabs in a New Tab by right clicking on it. Also at the same time we wanted that Active tabs must not behave as links. We wanted that tabs should behave in a similar way as Google, Bing and other search engine.In this blog, I will describe how we have achieved this by using routerLink and [hidden] attribute in Angular.

Steps:

1.Adding routerLink attribute in anchor tag.

Now, To make any element as link we must enclose it in anchor tag, therefore we will use <a> tag enclosing the <li> tag to make it a link.

<a [routerLink]="['/search']" [queryParams]="{query:this.searchdata.query,start:this.searchdata.start,rows:this.searchdata.rows,resultDisplay:'all',mode:'text',nopagechange:'false',append:'false'}"><li [class.active_view]="Display('all')" (click)="docClick()">All</li></a>
<a [routerLink]="['/search']" [queryParams]="{query:this.searchdata.query,start:this.searchdata.start,rows:this.searchdata.rows,mode:'text',nopagechange:'false',append:'false',fq:'url_file_ext_s%3A(png%2BOR%2Bjpeg%2BOR%2Bjpg%2BOR%2Bgif)',resultDisplay:'images'}"><li [class.active_view]="Display('images')" (click)="imageClick()">Images</li></a>
<a [routerLink]="['/search']" [queryParams]="{query:this.searchdata.query,start:this.searchdata.start,rows:this.searchdata.rows,resultDisplay:'videos',mode:'text',nopagechange:'false',append:'false',fq:'url_file_ext_s%3A(avi%2BOR%2Bmov%2BOR%2Bflv%2BOR%2Bmp4)'}"><li [class.active_view]="Display('videos')" (click)="videoClick()">Videos</li></a>
<a [routerLink]="['/search']" [queryParams]="{query:this.searchdata.query,start:this.searchdata.start,rows:this.searchdata.rows,resultDisplay:'news',mode:'text',nopagechange:'false',append:'false'}"><li [class.active_view]="Display('news')" (click)="newsClick()">News</li></a>

Now we must navigate to a link on the click of this tabs, for this we can simply use href attribute which we earlier tried to use but there is a disadvantage of using href tag. Using href tab reloads the whole page when we try to navigate to another tab.

Therefore we will use routerLink to achieve the same functionality as Susper is a single page application, where the page should not be reloaded. routerLink navigates to the new url and the component is rendered in place of <router-outlet> without reloading the whole page.

After using routerLink, we will use queryParams attribute to pass routing parameters to a route. Since these parameters will be variable we must use string interpolation to set query parameters. We will use searchdata object and set query parameters according to its value.

Now we are done with making tabs as links. But as of now all tabs will behave a links even if it is an active tab. Therefore we need to hide the link property of any tab when it is active.

2.Hiding the link property of the active tab:

Now we will use to different elements for each tab, one as link and other as normal li element.For hiding the link elements when the tab is active we will use [hidden] attribute in angular. We will just hide the link element when the value of resultDisplay variable is similar to current tab.

<a [routerLink]="['/search']" [queryParams]="{query:this.searchdata.query,start:this.searchdata.start,rows:this.searchdata.rows,resultDisplay:'all',mode:'text',nopagechange:'false',append:'false'}" [hidden]="this.resultDisplay==='all'"><li [class.active_view]="Display('all')" (click)="docClick()">All</li></a>
        <li [class.active_view]="Display('all')" (click)="docClick()" *ngIf="Display('all')">All</li>

For hiding the simple li element we will use *ngIf attribute which will remove the simple li element from the DOM for un active tabs. We might have used *ngIf attribute to hide link elements but rendering a lot of elements on DOM slows down the page and affects performance.

We will follow this for rest of the tabs also and we are done with our changes.

Now we can the inactive tabs will behave as link and the active tabs will not behave as link similar to Google.

Resources

  1. Angular Routing: https://angular.io/guide/router
  2. ngIf and [hidden]: https://stackoverflow.com/questions/39777990/angular2-conditional-display-bind-to-hidden-property-vs-ngif-directive
  3. Angular queryParams: https://stackoverflow.com/a/46008187
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