Allow link-active to react to linkTo input changes

lib/link-active.ts

@@ -4,6 +4,7 @@ import {
   ElementRef,
   Input,
   OnDestroy,
+  OnInit,
   Query,
   QueryList,
   Renderer,
@@ -13,6 +14,8 @@ import {
 } from '@angular/core';
 import { LinkTo } from './link-to';
 import { Router } from './router';
+import { Observable } from 'rxjs/Observable';
+import 'rxjs/add/operator/mergeAll';
 
 export interface LinkActiveOptions {
   exact: boolean;
@@ -33,11 +36,12 @@ export const LINK_ACTIVE_OPTIONS: LinkActiveOptions = {
  * </ol>
  */
  @Directive({ selector: '[linkActive]' })
- export class LinkActive implements AfterViewInit, OnDestroy {
+ export class LinkActive implements AfterViewInit, OnInit, OnDestroy {
    @Input('linkActive') activeClass: string = 'active';
    @Input() activeOptions: LinkActiveOptions;
-   private _sub: any;
    private _activeOptions: LinkActiveOptions = { exact: true };
+   private _routerSub: any;
+   private _linksSub: any;
 
    constructor(
      @Query(LinkTo) public links: QueryList<LinkTo>,
@@ -49,14 +53,20 @@ export const LINK_ACTIVE_OPTIONS: LinkActiveOptions = {
       private defaultActiveOptions: LinkActiveOptions
    ) {}
 
+   ngOnInit () {
+     this.links.changes.subscribe(_ => {
+       this.subscribeLinks();
+     });
+   }
+
    ngAfterViewInit() {
      if (this.defaultActiveOptions && !this.activeOptions) {
        this._activeOptions = this.defaultActiveOptions;
      } else if (this.activeOptions) {
        this._activeOptions = this.activeOptions;
      }
 
-     this._sub = this.router$
+     this._routerSub = this.router$
      .map(({path}) => this.router$.prepareExternalUrl(path || '/'))
      .subscribe(path => {
        this.checkActive(path);
@@ -80,9 +90,28 @@ export const LINK_ACTIVE_OPTIONS: LinkActiveOptions = {
      });
    }
 
+   subscribeLinks() {
+     if (this._linksSub) {
+       this._linksSub.unsubscribe();
+     }
+
+     let observables = this.links.map(link => {
+       return link.hrefUpdated;
+     });
+
+     this._linksSub = Observable.from(observables)
+       .mergeAll()
+       .subscribe(_ => {
+         this.checkActive(this.router$.prepareExternalUrl(this.router$.path() || '/'));
+       });
+   }
+
    ngOnDestroy() {
-     if (this._sub) {
-       this._sub.unsubscribe();
+     if (this._routerSub) {
+       this._routerSub.unsubscribe();
+     }
+     if (this._linksSub) {
+       this._linksSub.unsubscribe();
      }
    }
  }

lib/link-to.ts

@@ -1,4 +1,4 @@
-import { Directive, HostBinding, HostListener, Input } from  '@angular/core';
+import { Directive, HostBinding, HostListener, Input, Output, EventEmitter } from  '@angular/core';
 import { Router } from './router';
 
 /**
@@ -25,6 +25,8 @@ export class LinkTo {
     this._updateHref();
   }
 
+  @Output() hrefUpdated: EventEmitter<string> = new EventEmitter<string>();
+
   private _href: string;
   private _query: string | Object;
 
@@ -47,6 +49,7 @@ export class LinkTo {
     let path = this._cleanUpHref(this._href);
 
     this.linkHref = this._router.prepareExternalUrl(path, this._query);
+    this.hrefUpdated.emit(this.linkHref);
   }
 
   /**

spec/link-active.spec.ts

@@ -6,7 +6,9 @@ import {
   iit,
   async,
   inject,
-  expect
+  expect,
+  fakeAsync,
+  tick
 } from '@angular/core/testing';
 import { MockLocationStrategy, SpyLocation } from '@angular/common/testing';
 import { TestComponentBuilder } from '@angular/compiler/testing';
@@ -24,7 +26,10 @@ import { ROUTER_PROVIDERS, Router } from '../lib/router';
   template: '',
   directives: [LinkTo, LinkActive]
 })
-class TestComponent {}
+class TestComponent {
+  public link1: string;
+  public link2: string;
+}
 
 const compile = (tcb: TestComponentBuilder, template: string = '') => {
   return tcb
@@ -73,6 +78,36 @@ describe('Link Active', () => {
       });
   })));
 
+  it('should react to changes to the linkTo parameter', fakeAsync(inject([TestComponentBuilder, Router], (tcb, router$) => {
+    router$.go('/page');
+
+    return compile(tcb, `
+        <a id="page" linkActive="active" [linkTo]="link1">Page</a>
+        <a id="other" linkActive="active" [linkTo]="link2">Other</a>`)
+      .then((fixture) => {
+        let component = fixture.componentInstance as TestComponent;
+        let compiled = fixture.debugElement.nativeElement;
+        let linkPage: Element = compiled.querySelector('a#page');
+        let linkOther: Element = compiled.querySelector('a#other');
+
+        component.link1 = '/page';
+        component.link2 = '/other';
+        fixture.detectChanges();
+        tick();
+
+        expect(linkPage.getAttribute('class')).toEqual('active');
+        expect(linkOther.getAttribute('class')).not.toEqual('active');
+
+        component.link1 = '/other';
+        component.link2 = '/page';
+        fixture.detectChanges();
+        tick();
+
+        expect(linkPage.getAttribute('class')).not.toEqual('active');
+        expect(linkOther.getAttribute('class')).toEqual('active');
+      });
+  })));
+
   it('should support multiple classes on the active element', async(inject([TestComponentBuilder, Router], (tcb, router$) => {
     router$.next({
       path: '/page'