refactor canonicalURL into computed property

app/routes/project-version.js

@@ -1,7 +1,7 @@
 import Ember from 'ember';
 import _ from 'lodash';
 
-const { inject, run } = Ember;
+const { inject } = Ember;
 
 export default Ember.Route.extend({
   projectService: Ember.inject.service('project'),
@@ -21,35 +21,17 @@ export default Ember.Route.extend({
     const id = `${params.project}-${version}`;
     const projectVersion = await this.store.findRecord('project-version', id, { includes: 'project' });
 
-    this.setCanonicalURL(params, projectVersion);
+    this.injectDataIntoHeadModel(params, projectVersion);
 
     return projectVersion;
 
   },
 
-  setCanonicalURL({project_version}, versionModel) {
-    if (project_version !== 'lts' && project_version !== 'release') {
-
-
-      // run next is required so router.currentURL is present
-      // but it can be performance issue
-      // constructing the URL via href-to helper could be a good alternative
-      run.next(() => {
-        const currentURL = this.get('router.currentURL') || "";
-
-        if (versionModel.get('isRelease')) {
-          this.set('headData.canonicalURL', currentURL.replace(project_version, 'release'));
-        } else if (versionModel.get('isLTS')) {
-          this.set('headData.canonicalURL', currentURL.replace(project_version, 'lts'));
-        } else {
-          this.set('headData.canonicalURL', null);
-        }
-
-      });
-
-    } else {
-      this.set('headData.canonicalURL', null);
-    } 
+  injectDataIntoHeadModel({project_version}, projectVersionModel) {
+    this.get('headData').setProperties({
+      projectVersionModel,
+      projectVersionParam: project_version
+    });
   },
 
   // Using redirect instead of afterModel so transition succeeds and returns 30

app/services/head-data.js

@@ -0,0 +1,34 @@
+import Ember from 'ember';
+import HeadDataService from 'ember-cli-head/services/head-data';
+
+const { computed, inject } = Ember;
+
+export default HeadDataService.extend({
+
+  router: inject.service(),
+
+  projectVersionParam: null, //injected in project-version route
+  projectVersionModel: null, // injected in project-version route
+
+  canonicalURL: computed('projectVersionModel.{isRelease,isLTS}', 'router.currentURL', 'projectVersionParam', function() {
+    const versionParam = this.get('projectVersionParam');
+    if (versionParam !== 'release' && versionParam !== 'lts') {
+      const versionModel = this.get('projectVersionModel');
+      const currentURL = this.get('router.currentURL') || "";
+
+      if (versionModel) {
+        if (versionModel.get('isRelease')) {
+          return currentURL.replace(versionParam, 'release');
+        } else if (versionModel.get('isLTS')) {
+          return currentURL.replace(versionParam, 'lts');
+        }
+      }
+
+      return null;
+    }
+
+    return null;
+
+  })
+
+});

tests/acceptance/release-lts-project-versions-test.js

@@ -1,9 +1,7 @@
 import { test } from 'qunit';
 import moduleForAcceptance from 'ember-api-docs/tests/helpers/module-for-acceptance';
-import { click } from 'ember-native-dom-helpers';
+import { click, visit } from 'ember-native-dom-helpers';
 import Ember from 'ember';
-import { visit } from 'ember-native-dom-helpers';
-
 
 const {$} = Ember;