Improve PaginationRoute mixin

no issue
- returns the promise/result from `loadNextPage` so that it's return value can be utilised in closure actions
- sets the `isLoading` property in `loadFirstPage` to match `loadNextPage` behaviour
- reset the `isLoading` property even if the request fails
- adds a `didReceivePaginationMeta` hook so that consumers of the mixin can use the metadata values without having to rely on observers
  - eg. pulling the `total` into a separate property that can be manipulated when items are added/removed but still reset to the sever's total value the next time a page is loaded
- renames the `pagination-route` mixin to simply `pagination` as it's not tied to routes and works equally well in other objects that need to paginate an API resource

ghost/admin/app/mixins/pagination.js

@@ -3,6 +3,7 @@ import getRequestErrorMessage from 'ghost/utils/ajax';
 
 const {
     Mixin,
+    computed,
     inject: {service}
 } = Ember;
 
@@ -16,7 +17,20 @@ export default Mixin.create({
 
     paginationModel: null,
     paginationSettings: null,
-    paginationMeta: null,
+
+    // add a hook so that routes/controllers can do something with the meta data
+    paginationMeta: computed({
+        get() {
+            return this._paginationMeta;
+        },
+        set(key, value) {
+            if (this.didReceivePaginationMeta) {
+                this.didReceivePaginationMeta(value);
+            }
+            this._paginationMeta = value;
+            return value;
+        }
+    }),
 
     init() {
         let paginationSettings = this.get('paginationSettings');
@@ -51,11 +65,15 @@ export default Mixin.create({
 
         paginationSettings.page = 1;
 
+        this.set('isLoading', true);
+
         return this.get('store').query(modelName, paginationSettings).then((results) => {
             this.set('paginationMeta', results.meta);
             return results;
-        }, (response) => {
+        }).catch((response) => {
             this.reportLoadError(response);
+        }).finally(() => {
+            this.set('isLoading', false);
         });
     },
 
@@ -79,12 +97,13 @@ export default Mixin.create({
                 this.set('isLoading', true);
                 this.set('paginationSettings.page', nextPage);
 
-                store.query(modelName, paginationSettings).then((results) => {
-                    this.set('isLoading', false);
+                return store.query(modelName, paginationSettings).then((results) => {
                     this.set('paginationMeta', results.meta);
                     return results;
-                }, (response) => {
+                }).catch((response) => {
                     this.reportLoadError(response);
+                }).finally(() => {
+                    this.set('isLoading', false);
                 });
             }
         },

ghost/admin/app/routes/posts.js

@@ -1,9 +1,9 @@
 import Ember from 'ember';
 import AuthenticatedRoute from 'ghost/routes/authenticated';
 import ShortcutsRoute from 'ghost/mixins/shortcuts-route';
-import PaginationRouteMixin from 'ghost/mixins/pagination-route';
+import PaginationMixin from 'ghost/mixins/pagination';
 
-export default AuthenticatedRoute.extend(ShortcutsRoute, PaginationRouteMixin, {
+export default AuthenticatedRoute.extend(ShortcutsRoute, PaginationMixin, {
     titleToken: 'Content',
 
     paginationModel: 'post',

ghost/admin/app/routes/settings/tags.js

@@ -3,9 +3,9 @@ import Ember from 'ember';
 import AuthenticatedRoute from 'ghost/routes/authenticated';
 import CurrentUserSettings from 'ghost/mixins/current-user-settings';
 import ShortcutsRoute from 'ghost/mixins/shortcuts-route';
-import PaginationRoute from 'ghost/mixins/pagination-route';
+import PaginationMixin from 'ghost/mixins/pagination';
 
-export default AuthenticatedRoute.extend(CurrentUserSettings, PaginationRoute, ShortcutsRoute, {
+export default AuthenticatedRoute.extend(CurrentUserSettings, PaginationMixin, ShortcutsRoute, {
     titleToken: 'Settings - Tags',
 
     paginationModel: 'tag',

ghost/admin/app/routes/team/index.js

@@ -1,9 +1,9 @@
 import AuthenticatedRoute from 'ghost/routes/authenticated';
 import CurrentUserSettings from 'ghost/mixins/current-user-settings';
-import PaginationRouteMixin from 'ghost/mixins/pagination-route';
+import PaginationMixin from 'ghost/mixins/pagination';
 import styleBody from 'ghost/mixins/style-body';
 
-export default AuthenticatedRoute.extend(styleBody, CurrentUserSettings, PaginationRouteMixin, {
+export default AuthenticatedRoute.extend(styleBody, CurrentUserSettings, PaginationMixin, {
     titleToken: 'Team',
 
     classNames: ['view-team'],