Infinite Scroll on Posts List

closes #2414
- Add PostsController with loadNextPage action
- Collect and store pagination info from PostsRoute into PostsController
- Use `store.filter` on PostsRoute model hook to auto-update posts list template as post models are added to the store
- Add content list view and use it to check for scroll event
- Make PostRoute only load a post that's already in the store, until we figure how to load multiple pages on refresh
- Add util function from clientold that concats error messages from server response

core/client/controllers/posts.js

@@ -0,0 +1,65 @@
+import { getRequestErrorMessage } from 'ghost/utils/ajax';
+
+var PostsController = Ember.ArrayController.extend({
+    // set from PostsRoute
+    paginationSettings: null,
+
+    // holds the next page to load during infinite scroll
+    nextPage: null,
+
+    // indicates whether we're currently loading the next page
+    isLoading: null,
+
+    init: function () {
+        this._super();
+
+        var metadata = this.store.metadataFor('post');
+        this.set('nextPage', metadata.pagination.next);
+    },
+
+    /**
+     * Takes an ajax response, concatenates any error messages, then generates an error notification.
+     * @param {jqXHR} response The jQuery ajax reponse object.
+     * @return
+     */
+    reportLoadError: function (response) {
+        var message = 'A problem was encountered while loading more posts';
+
+        if (response) {
+            // Get message from response
+            message += ': ' + getRequestErrorMessage(response);
+        } else {
+            message += '.';
+        }
+
+        this.notifications.showError(message);
+    },
+
+    actions: {
+        /**
+        * Loads the next paginated page of posts into the ember-data store. Will cause the posts list UI to update.
+        * @return
+        */
+        loadNextPage: function () {
+            var self = this,
+                store = this.get('store'),
+                nextPage = this.get('nextPage'),
+                paginationSettings = this.get('paginationSettings');
+
+            if (nextPage) {
+                this.set('isLoading', true);
+                this.set('paginationSettings.page', nextPage);
+                store.find('post', paginationSettings).then(function () {
+                    var metadata = store.metadataFor('post');
+
+                    self.set('nextPage', metadata.pagination.next);
+                    self.set('isLoading', false);
+                }, function (response) {
+                    self.reportLoadError(response);
+                });
+            }
+        }
+    }
+});
+
+export default PostsController;

core/client/routes/posts.js

@@ -1,11 +1,27 @@
 import styleBody from 'ghost/mixins/style-body';
 import AuthenticatedRoute from 'ghost/routes/authenticated';
 
+var paginationSettings = {
+    status: 'all',
+    staticPages: 'all',
+    page: 1,
+    limit: 15
+};
+
 var PostsRoute = AuthenticatedRoute.extend(styleBody, {
     classNames: ['manage'],
 
     model: function () {
-        return this.store.find('post', { status: 'all', staticPages: 'all' });
+        // using `.filter` allows the template to auto-update when new models are pulled in from the server.
+        // we just need to 'return true' to allow all models by default.
+        return this.store.filter('post', paginationSettings, function () {
+            return true;
+        });
+    },
+
+    setupController: function (controller, model) {
+        this._super(controller, model);
+        controller.set('paginationSettings', paginationSettings);
     },
 
     actions: {

core/client/routes/posts/post.js

@@ -1,5 +1,11 @@
 export default Ember.Route.extend({
     model: function (params) {
-        return this.store.find('post', params.post_id);
+        var post = this.modelFor('posts').findBy('id', params.post_id);
+
+        if (!post) {
+            this.transitionTo('posts.index');
+        }
+
+        return post;
     }
 });

core/client/templates/posts.hbs

@@ -6,7 +6,7 @@
             </section>
             {{#link-to "new" class="button button-add" title="New Post"}}<span class="hidden">New Post</span>{{/link-to}}
         </header>
-        <section class="content-list-content">
+        {{#view 'content-list-content-view' tagName="section"}}
             <ol class="posts-list">
                 {{#each itemController="posts/post" itemView="post-item-view" itemTagName="li"}}
                     {{!-- @TODO: Restore functionality where 'featured' and 'page' classes are added for proper posts --}}
@@ -30,7 +30,7 @@
                     {{/link-to}}
                 {{/each}}
             </ol>
-        </section>
+        {{/view}}
     </section>
     <section class="content-preview js-content-preview">
         {{outlet}}

core/client/utils/ajax.js

@@ -1,4 +1,43 @@
 /* global ic */
-export default window.ajax = function () {
+
+var ajax = window.ajax = function () {
     return ic.ajax.request.apply(null, arguments);
 };
+
+// Used in API request fail handlers to parse a standard api error
+// response json for the message to display
+var getRequestErrorMessage = function (request) {
+    var message,
+        msgDetail;
+
+    // Can't really continue without a request
+    if (!request) {
+        return null;
+    }
+
+    // Seems like a sensible default
+    message = request.statusText;
+
+    // If a non 200 response
+    if (request.status !== 200) {
+        try {
+            // Try to parse out the error, or default to "Unknown"
+            if (request.responseJSON.errors && Ember.isArray(request.responseJSON.errors)) {
+
+                message = request.responseJSON.errors.map(function (errorItem) {
+                    return errorItem.message;
+                }).join('; ');
+            } else {
+                message =  request.responseJSON.error || "Unknown Error";
+            }
+        } catch (e) {
+            msgDetail = request.status ? request.status + " - " + request.statusText : "Server was not available";
+            message = "The server returned an error (" + msgDetail + ").";
+        }
+    }
+
+    return message;
+};
+
+export { getRequestErrorMessage, ajax };
+export default ajax;

core/client/views/content-list-content-view.js

@@ -0,0 +1,29 @@
+var PostsListView = Ember.View.extend({
+    classNames: ['content-list-content'],
+
+    checkScroll: function (event) {
+        var element = event.target,
+            triggerPoint = 100,
+            controller = this.get('controller'),
+            isLoading = controller.get('isLoading');
+
+        // If we haven't passed our threshold, exit
+        if (isLoading || (element.scrollTop + element.clientHeight + triggerPoint <= element.scrollHeight)) {
+            return;
+        }
+
+        controller.send('loadNextPage');
+    },
+
+    didInsertElement: function () {
+        var el = this.$();
+        el.bind('scroll', Ember.run.bind(this, this.checkScroll));
+    },
+
+    willDestroyElement: function () {
+        var el = this.$();
+        el.unbind('scroll');
+    }
+});
+
+export default PostsListView;