title: how to use pipe for router link in angular2?
body: <p>i have 3 link for navigate to 3 page.all three pages almost  do one work:</p>
  
  <pre class="lang-html prettyprint-override"><code> &lt;a *ngIf="item.questionnaireType==1" class="primary small ui icon button" [routerLink]="['/UpdateLikert', item.id]" title="edit"&gt;
     &lt;i class="edit   icon"&gt;&lt;/i&gt;
   &lt;/a&gt;
   &lt;a *ngIf="item.questionnaireType==2" class="primary small ui icon button" [routerLink]="['/UpdateForceChoice', item.id]" title="edit"&gt;
     &lt;i class="edit  icon"&gt;&lt;/i&gt;
   &lt;/a&gt;
   &lt;a *ngIf="item.questionnaireType==3" class="primary small ui icon button" [routerLink]="['/UpdateChoice', item.id]" title="edit"&gt;
     &lt;i class="edit  icon"&gt;&lt;/i&gt;
   &lt;/a&gt;
  </code></pre>
  
  <p>but i want to have a link that dynamically route to page by it's questionnairetype.
  then i create a pipe and inject in component and use it by bellow way:</p>
  
  <pre class="lang-ts prettyprint-override"><code>  &lt;-- pipe --&gt;
    import { Pipe, PipeTransform } from '@angular/core';
  
    @Pipe({
      name: 'questionnaireTypeForRoute'
    })
    export class QuestionnaireTypeForRoutePipe implements PipeTransform {
      transform(value: number, args?: any): string {
        switch (value) {
          case 1: return "/UpdateLikert";
          case 2: return "/UpdateForceChoice";
          case 3: return "/UpdateChoice";
        }
      }
    }
  </code></pre>
  
  <p>using one link after create pipe:</p>
  
  <pre class="lang-html prettyprint-override"><code> &lt;a  class="primary small ui icon button" [routerLink]="[{{item.questionnaireType | questionnaireTypeForRoute}}, item.id]" title="edit"&gt;
     &lt;i class="edit icon"&gt;&lt;/i&gt;
   &lt;/a&gt;
  </code></pre>
  
  <p>then i  get template parse error.
  is there any way to use pipe for url of routerLink ?</p>