From a318bb49527dd13f0fcecc7c500fe472ba3002ba Mon Sep 17 00:00:00 2001
From: Toby Zerner <toby.zerner@gmail.com>
Date: Fri, 6 Feb 2015 10:30:38 +1030
Subject: [PATCH] Load discussion and posts with one request

Speeds things up a heap.
Also fix a whole bunch of bugs with the post stream.
---
 .../components/discussions/stream-content.js  | 51 ++++++++-----
 .../components/discussions/stream-scrubber.js | 11 ++-
 .../core/ember/app/controllers/discussion.js  | 31 +-------
 .../ember/app/initializers/find-query-one.js  | 25 ++++++
 .../core/ember/app/models/post-stream.js      | 42 +++++++---
 framework/core/ember/app/routes/discussion.js | 76 +++++++++++++------
 framework/core/ember/app/views/discussion.js  | 45 +++--------
 .../core/src/Flarum/Api/Actions/Base.php      |  9 ++-
 .../Flarum/Api/Actions/Discussions/Show.php   | 32 +++++++-
 .../Actions/Posts/GetsPostsForDiscussion.php  | 19 +++++
 .../src/Flarum/Api/Actions/Posts/Index.php    | 63 +++++++--------
 .../Api/Serializers/DiscussionSerializer.php  |  5 +-
 .../src/Flarum/Core/Posts/PostRepository.php  | 34 +++++++++
 13 files changed, 279 insertions(+), 164 deletions(-)
 create mode 100644 framework/core/ember/app/initializers/find-query-one.js
 create mode 100644 framework/core/src/Flarum/Api/Actions/Posts/GetsPostsForDiscussion.php

diff --git a/framework/core/ember/app/components/discussions/stream-content.js b/framework/core/ember/app/components/discussions/stream-content.js
index 796c65918..703314ba9 100644
--- a/framework/core/ember/app/components/discussions/stream-content.js
+++ b/framework/core/ember/app/components/discussions/stream-content.js
@@ -24,6 +24,11 @@ export default Ember.Component.extend({
 		return this.get('loaded') && ! this.get('paused');
 	}.property('loaded', 'paused'),
 
+	refresh: function() {
+		this.set('paused', true);
+		clearTimeout(this.updateStateTimeout);
+	}.observes('stream'),
+
 	didInsertElement: function() {
 		$(window).on('scroll', {view: this}, this.windowWasScrolled);
 	},
@@ -105,41 +110,41 @@ export default Ember.Component.extend({
 		}, 250);
 	}.observes('active'),
 
-	loadingNumber: function(number) {
+	loadingNumber: function(number, noAnimation) {
 		// The post with this number is being loaded. We want to scroll to where
 		// we think it will appear. We may be scrolling to the edge of the page,
 		// but we don't want to trigger any terminal post gaps to load by doing
 		// that. So, we'll disable the window's scroll handler for now.
 		this.set('paused', true);
-		this.jumpToNumber(number);
+		this.jumpToNumber(number, noAnimation);
 	},
 
-	loadedNumber: function(number) {
+	loadedNumber: function(number, noAnimation) {
 		// The post with this number has been loaded. After we scroll to this
 		// post, we want to resume scroll events.
 		var view = this;
 		Ember.run.scheduleOnce('afterRender', function() {
-			view.jumpToNumber(number).done(function() {
+			view.jumpToNumber(number, noAnimation).done(function() {
 				view.set('paused', false);
 			});
 		});
 	},
 
-	loadingIndex: function(index) {
+	loadingIndex: function(index, noAnimation) {
 		// The post at this index is being loaded. We want to scroll to where we
 		// think it will appear. We may be scrolling to the edge of the page,
 		// but we don't want to trigger any terminal post gaps to load by doing
 		// that. So, we'll disable the window's scroll handler for now.
 		this.set('paused', true);
-		this.jumpToIndex(index);
+		this.jumpToIndex(index, noAnimation);
 	},
 
-	loadedIndex: function(index) {
+	loadedIndex: function(index, noAnimation) {
 		// The post at this index has been loaded. After we scroll to this post,
 		// we want to resume scroll events.
 		var view = this;
 		Ember.run.scheduleOnce('afterRender', function() {
-			view.jumpToIndex(index).done(function() {
+			view.jumpToIndex(index, noAnimation).done(function() {
 				view.set('paused', false);
 			});
 		});
@@ -147,7 +152,7 @@ export default Ember.Component.extend({
 
 	// Scroll down to a certain post by number (or the gap which we think the
 	// post is in) and highlight it.
-	jumpToNumber: function(number) {
+	jumpToNumber: function(number, noAnimation) {
 		// Clear the highlight class from all posts, and attempt to find and
 		// highlight a post with the specified number. However, we don't apply
 		// the highlight to the first post in the stream because it's pretty
@@ -165,22 +170,26 @@ export default Ember.Component.extend({
 			$item = this.findNearestToNumber(number);
 		}
 
-		return this.scrollToItem($item);
+		return this.scrollToItem($item, noAnimation);
 	},
 
 	// Scroll down to a certain post by index (or the gap the post is in.)
-	jumpToIndex: function(index) {
+	jumpToIndex: function(index, noAnimation) {
 		var $item = this.findNearestToIndex(index);
-		return this.scrollToItem($item);
+		return this.scrollToItem($item, noAnimation);
 	},
 
-	scrollToItem: function($item) {
+	scrollToItem: function($item, noAnimation) {
 		var $container = $('html, body');
 		if ($item.length) {
 			var marginTop = this.getMarginTop();
 			var scrollTop = $item.is(':first-child') ? 0 : $item.offset().top - marginTop;
 			if (scrollTop !== $(document).scrollTop()) {
-				$container.stop(true).animate({scrollTop: scrollTop});
+				if (noAnimation) {
+					$container.stop(true).scrollTop(scrollTop);
+				} else {
+					$container.stop(true).animate({scrollTop: scrollTop});
+				}
 			}
 		}
 		return $container.promise();
@@ -221,35 +230,35 @@ export default Ember.Component.extend({
     },
 
     actions: {
-    	goToNumber: function(number) {
+    	goToNumber: function(number, noAnimation) {
             number = Math.max(number, 1);
 
             // Let's start by telling our listeners that we're going to load
             // posts near this number. Elsewhere we will listen and
             // consequently scroll down to the appropriate position.
-            this.trigger('loadingNumber', number);
+            this.trigger('loadingNumber', number, noAnimation);
 
             // Now we have to actually make sure the posts around this new start
             // position are loaded. We will tell our listeners when they are.
             // Again, a listener will scroll down to the appropriate post.
             var controller = this;
             this.get('stream').loadNearNumber(number).then(function() {
-                controller.trigger('loadedNumber', number);
+                controller.trigger('loadedNumber', number, noAnimation);
             });
         },
 
-        goToIndex: function(index, backwards) {
+        goToIndex: function(index, backwards, noAnimation) {
             // Let's start by telling our listeners that we're going to load
             // posts at this index. Elsewhere we will listen and consequently
             // scroll down to the appropriate position.
-            this.trigger('loadingIndex', index);
+            this.trigger('loadingIndex', index, noAnimation);
 
             // Now we have to actually make sure the posts around this index
             // are loaded. We will tell our listeners when they are. Again, a
             // listener will scroll down to the appropriate post.
             var controller = this;
             this.get('stream').loadNearIndex(index, backwards).then(function() {
-                controller.trigger('loadedIndex', index);
+                controller.trigger('loadedIndex', index, noAnimation);
             });
         },
 
@@ -276,4 +285,4 @@ export default Ember.Component.extend({
             this.get('stream').loadRange(start, end, backwards);
         }
     }
-});
\ No newline at end of file
+});
diff --git a/framework/core/ember/app/components/discussions/stream-scrubber.js b/framework/core/ember/app/components/discussions/stream-scrubber.js
index 29ee00631..95c855e4d 100644
--- a/framework/core/ember/app/components/discussions/stream-scrubber.js
+++ b/framework/core/ember/app/components/discussions/stream-scrubber.js
@@ -218,10 +218,13 @@ export default Ember.Component.extend({
 	// after a bunch of posts have been loaded), then we want to update the
 	// scrubber scrollbar according to the window's current scroll position.
 	resume: function() {
-		if (this.get('streamContent.active')) {
-			this.update();
-			this.updateScrollbar(true);
-		}
+		var scrubber = this;
+		Ember.run.scheduleOnce('afterRender', function() {
+			if (scrubber.get('streamContent.active')) {
+				scrubber.update();
+				scrubber.updateScrollbar(true);
+			}
+		});
 	}.observes('streamContent.active'),
 
 	// Update the index/visible/description properties according to the
diff --git a/framework/core/ember/app/controllers/discussion.js b/framework/core/ember/app/controllers/discussion.js
index b2a3d97bf..5c26b53cf 100644
--- a/framework/core/ember/app/controllers/discussion.js
+++ b/framework/core/ember/app/controllers/discussion.js
@@ -1,12 +1,10 @@
 import Ember from 'ember';
 
-import PostStream from '../models/post-stream';
 import ComposerReply from '../components/discussions/composer-reply';
 import ActionButton from '../components/ui/controls/action-button';
 import AlertMessage from '../components/alert-message';
 
 export default Ember.ObjectController.extend(Ember.Evented, {
-
     needs: ['application', 'composer'],
     
     queryParams: ['start'],
@@ -16,31 +14,6 @@ export default Ember.ObjectController.extend(Ember.Evented, {
     loaded: false,
     stream: null,
 
-    setup: function(discussion) {
-        this.set('model', discussion);
-
-        // Set up the post stream object. It needs to know about the discussion
-        // its representing the posts for, and we also need to inject the Ember
-        // data store.
-        var stream = PostStream.create();
-        stream.set('discussion', discussion);
-        stream.set('store', this.get('store'));
-        this.set('stream', stream);
-
-        // Next, we need to load a list of the discussion's post IDs into the
-        // post stream object. If we don't already have this information, we'll
-        // need to reload the discussion model.
-        var promise = discussion.get('posts') ? Ember.RSVP.resolve(discussion) : discussion.reload();
-
-        // When we know we have the post IDs, we can set up the post stream with
-        // them. Then the view will trigger the stream to load as it sees fit.
-        var controller = this;
-        promise.then(function(discussion) {
-            stream.setup(discussion.get('postIds'));
-            controller.set('loaded', true);
-        });
-    },
-
     // Save a reply. This may be called by a composer-reply component that was
     // set up on a different discussion, so we require a discussion model to
     // be explicitly passed rather than using the controller's implicit one.
@@ -61,7 +34,6 @@ export default Ember.ObjectController.extend(Ember.Evented, {
             composer.send('hide');
 
             discussion.setProperties({
-                posts: discussion.get('posts')+','+post.get('id'),
                 lastTime: post.get('time'),
                 lastUser: post.get('user'),
                 lastPost: post,
@@ -74,8 +46,7 @@ export default Ember.ObjectController.extend(Ember.Evented, {
             // If we're currently viewing the discussion which this reply was
             // made in, then we can add the post to the end of the post
             // stream.
-            if (discussion == controller.get('model')) {
-                stream.set('ids', discussion.get('postIds'));
+            if (discussion == controller.get('model') && stream) {
                 stream.addPostToEnd(post);
             } else {
                 // Otherwise, we'll create an alert message to inform the user
diff --git a/framework/core/ember/app/initializers/find-query-one.js b/framework/core/ember/app/initializers/find-query-one.js
new file mode 100644
index 000000000..6e9adc934
--- /dev/null
+++ b/framework/core/ember/app/initializers/find-query-one.js
@@ -0,0 +1,25 @@
+import DS from 'ember-data';
+
+// This can be removed when
+// https://github.com/emberjs/data/pull/2584 is implemented.
+
+export default {
+  name: 'find-query-one',
+  initialize: function(container) {
+    DS.Store.reopen({
+      findQueryOne: function(type, id, query) {
+        var store = this;
+        var typeClass = store.modelFor(type);
+        var adapter = store.adapterFor(typeClass);
+        var serializer = store.serializerFor(typeClass);
+        var url = adapter.buildURL(type, id);
+        var ajaxPromise = adapter.ajax(url, 'GET', { data: query });
+
+        return ajaxPromise.then(function(rawPayload) {
+          var extractedPayload = serializer.extract(store, typeClass, rawPayload, id, 'find');
+          return store.push(typeClass, extractedPayload);
+        });
+      }
+    });
+  }
+};
\ No newline at end of file
diff --git a/framework/core/ember/app/models/post-stream.js b/framework/core/ember/app/models/post-stream.js
index 1eb1c4e32..c759cbe90 100644
--- a/framework/core/ember/app/models/post-stream.js
+++ b/framework/core/ember/app/models/post-stream.js
@@ -15,15 +15,6 @@ export default Ember.ArrayProxy.extend(Ember.Evented, {
 
 	postLoadCount: 20,
 
-	_init: function() {
-		this.clear();
-	}.on('init'),
-
-	setup: function(ids) {
-		this.set('ids', ids);
-		this.get('content').objectAt(0).set('indexEnd', this.get('count') - 1);
-	},
-
 	count: Ember.computed.alias('ids.length'),
 
 	loadedCount: function() {
@@ -40,12 +31,35 @@ export default Ember.ArrayProxy.extend(Ember.Evented, {
 		return last && last.content;
 	}.property('content.@each'),
 
+	init: function() {
+		this._super();
+		this.set('ids', Ember.A());
+		this.clear();
+	},
+
+	setup: function(ids) {
+		// Set our ids to the array provided and reset the content of the
+		// stream to a big gap that covers the amount of posts we now have.
+		this.set('ids', ids);
+		this.clear();
+
+		// Look in the store and see if we already have the data for any of
+		// these posts. If we do, we can add them to the stream.
+		var posts = [];
+		var store = this.get('store');
+		ids.forEach(function(id) {
+			if (store.hasRecordForId('post', id)) {
+				posts.pushObject(store.getById('post', id));
+			}
+		});
+		this.addPosts(posts);
+	},
+
 	// Clear the contents of the post stream, resetting it to one big gap.
 	clear: function() {
 		var content = Ember.A();
 		content.clear().pushObject(this.makeItem(0, this.get('count') - 1).set('loading', true));
 		this.set('content', content);
-		this.set('ids', Ember.A());
 	},
 
 	loadRange: function(start, end, backwards) {
@@ -124,9 +138,12 @@ export default Ember.ArrayProxy.extend(Ember.Evented, {
 		this.trigger('postsLoaded', posts);
 
 		var stream = this;
+		var content = this.get('content');
+		content.beginPropertyChanges();
 		posts.forEach(function(post) {
 			stream.addPost(post);
 		});
+		content.endPropertyChanges();
 
 		this.trigger('postsAdded');
 	},
@@ -156,6 +173,7 @@ export default Ember.ArrayProxy.extend(Ember.Evented, {
 	},
 
 	addPostToEnd: function(post) {
+		this.get('ids').pushObject(post.get('id'));
 		var index = this.get('count') - 1;
         this.get('content').pushObject(this.makeItem(index, index, post));
 	},
@@ -171,10 +189,10 @@ export default Ember.ArrayProxy.extend(Ember.Evented, {
 	findNearestTo: function(index, property) {
 		var nearestItem;
         this.get('content').some(function(item) {
-            nearestItem = item;
             if (item.get(property) > index) {
                 return true;
             }
+            nearestItem = item;
         });
         return nearestItem;
 	},
@@ -184,6 +202,6 @@ export default Ember.ArrayProxy.extend(Ember.Evented, {
     },
 
     findNearestToIndex: function(index) {
-    	return this.findNearestTo(index, 'indexEnd');
+    	return this.findNearestTo(index, 'indexStart');
     }
 });
diff --git a/framework/core/ember/app/routes/discussion.js b/framework/core/ember/app/routes/discussion.js
index a818d4934..0731f0c77 100644
--- a/framework/core/ember/app/routes/discussion.js
+++ b/framework/core/ember/app/routes/discussion.js
@@ -1,13 +1,22 @@
 import Ember from 'ember';
 
-export default Ember.Route.extend({
+import PostStream from '../models/post-stream';
 
+export default Ember.Route.extend({
 	queryParams: {
 		start: {replace: true}
 	},
 
 	model: function(params) {
-		return this.store.find('discussion', params.id);
+		// Each time we view a discussion we want to reload its posts from
+		// scratch so that we have the most up-to-date data. Also, if we were
+		// to leave them in the store, the stream would try and render them
+		// which has the potential to be slow.
+		this.store.unloadAll('post');
+		return this.store.findQueryOne('discussion', params.id, {
+			include: 'posts',
+			near: params.start
+		});
 	},
 
 	resetController: function(controller) {
@@ -19,18 +28,42 @@ export default Ember.Route.extend({
 		controller.set('stream', null);
 	},
 
-	setupController: function(controller, model) {
-		controller.setup(model);
+	setupController: function(controller, discussion) {
+		controller.set('model', discussion);
 
-		// Tell the discussions controller that the discussions list should be
-		// displayed as a pane, hidden on the side of the screen. Also set the
-		// application back button's target as the discussions controller.
-		this.controllerFor('index').set('paned', true);
-		this.controllerFor('application').set('backButtonTarget', this.controllerFor('index'));
+        // Set up the post stream object. It needs to know about the discussion
+        // it's representing the posts for, and we also need to inject the Ember
+        // Data store.
+        var stream = PostStream.create({
+        	discussion: discussion,
+        	store: this.store
+        });
+        controller.set('stream', stream);
+
+        // Next, we need to make sure we have a list of the discussion's post
+        // IDs. If we don't already have this information, we'll need to
+        // reload the discussion model.
+        var promise = discussion.get('posts') ? Ember.RSVP.resolve(discussion) : this.model({
+        	id: discussion.get('id'),
+        	start: controller.get('start')
+        });
+
+        // When we know we have the post IDs, we can set up the post stream with
+        // them. Then we will tell the view that we have finished loading so that
+        // it can scroll down to the appropriate post.
+        promise.then(function(discussion) {
+            stream.setup(discussion.get('postIds'));
+            controller.store.push('discussion', {id: discussion.get('id'), posts: ''});
+            if (controller.get('model') === discussion) {
+	            controller.set('loaded', true);
+	            Ember.run.scheduleOnce('afterRender', function() {
+	            	controller.trigger('loaded');
+	            });
+	        }
+        });
 	},
 
 	actions: {
-
 		queryParamsDidChange: function(params) {
 			// If the ?start param has changed, we want to tell the view to
 			// tell the streamContent component to jump to this start point.
@@ -39,26 +72,25 @@ export default Ember.Route.extend({
 			// queryParamsDidChange is fired before the controller is reset.
 			// Thus, controller.loaded would still be true and the
 			// startWasChanged event would be triggered inappropriately.
-			var controller = this.get('controller'),
-			    oldStart = parseInt(this.get('controller.start'));
+			var newStart = parseInt(params.start) || 1;
+			var controller = this.controllerFor('discussion');
+			var oldStart = parseInt(controller.get('start'));
 			Ember.run.next(function() {
-				if (! params.start || ! controller || ! controller.get('loaded') || parseInt(params.start) === oldStart) {
-					return;
+				if (controller.get('loaded') && newStart !== oldStart) {
+					controller.trigger('startWasChanged', newStart);
 				}
-				controller.trigger('startWasChanged', params.start);
 			});
 		},
 
-		willTransition: function() {
+		didTransition: function() {
 			// When we transition into a new discussion, we want to hide the
 			// discussions list pane. This means that when the user selects a
 			// different discussion within the pane, the pane will slide away.
-			this.controllerFor('index').set('paneShowing', false);
+			// We also minimize the composer.
+			this.controllerFor('index')
+				.set('paned', true)
+				.set('paneShowing', false);
+			this.controllerFor('composer').send('minimize');
 		},
-
-	    didTransition: function() {
-	    	this.controllerFor('composer').send('minimize');
-	    }
-
 	}
 });
diff --git a/framework/core/ember/app/views/discussion.js b/framework/core/ember/app/views/discussion.js
index c9585f749..59da3d6ea 100644
--- a/framework/core/ember/app/views/discussion.js
+++ b/framework/core/ember/app/views/discussion.js
@@ -11,58 +11,37 @@ export default Ember.View.extend(Ember.Evented, {
 
 	sidebarItems: null,
 
-	loadingNumber: false,
-
 	didInsertElement: function() {
 		// Create and populate an array of items to be rendered in the sidebar.
 		var sidebarItems = TaggedArray.create();
 		this.trigger('populateSidebar', sidebarItems);
 		this.set('sidebarItems', sidebarItems);
 
-		// By this stage the discussion controller has initialized the post
-		// stream object, and there may or may not be posts loaded into it.
-		// Either way, we want to tell our stream content component to jump
-		// down to the start position specified in the controller's query
-		// params.
-		this.loadStreamContentForNewDiscussion();
-
-		// For that matter, whenever the controller's start query param
-		// changes, we want to tell our stream content component to jump down
-		// to it.
-		this.get('controller').on('startWasChanged', this, this.goToNumber);
-		this.get('streamContent').on('loadedNumber', this, this.loadedNumber);
+		this.get('controller').on('loaded', this, this.loaded);
+		this.get('controller').on('startWasChanged', this, this.startWasChanged);
 	},
 
 	willDestroyElement: function() {
-		this.get('controller').off('startWasChanged', this, this.goToNumber);
-		this.get('streamContent').off('loadedNumber', this, this.loadedNumber);
+		this.get('controller').off('loaded', this, this.loaded);
+		this.get('controller').off('startWasChanged', this, this.startWasChanged);
 	},
 
-	goToNumber: function(start) {
-		// We can only proceed if the controller has loaded the discussion
-		// details and the view has been rendered.
-		if (this.get('controller.loaded') && this.get('streamContent') && ! this.get('loadingNumber')) {
-			this.get('streamContent').send('goToNumber', start);
-			this.set('loadingNumber', true);
-		}
+	// When the controller has finished loading, we want to scroll down to the
+	// appropriate post instantly (without animation).
+	loaded: function() {
+		this.get('streamContent').send('goToNumber', this.get('controller.start'), true);
 	},
 
-	loadedNumber: function() {
-		this.set('loadingNumber', false);
+	// When the start position of the discussion changes, we want to scroll
+	// down to the appropriate post.
+	startWasChanged: function(start) {
+		this.get('streamContent').send('goToNumber', start);
 	},
 
 	// ------------------------------------------------------------------------
 	// OBSERVERS
 	// ------------------------------------------------------------------------
 
-	// Whenever the controller has switched out the old discussion model for a
-	// new one, we want to begin loading posts according to the ?start param.
-	loadStreamContentForNewDiscussion: function() {
-		if (this.get('controller.loaded')) {
-			this.goToNumber(this.get('controller.start'));
-		}
-	}.observes('controller.loaded'),
-
 	// Whenever the model's title changes, we want to update that document's
 	// title the reflect the new title.
 	updateTitle: function() {
diff --git a/framework/core/src/Flarum/Api/Actions/Base.php b/framework/core/src/Flarum/Api/Actions/Base.php
index a90b75602..df43dc5d4 100644
--- a/framework/core/src/Flarum/Api/Actions/Base.php
+++ b/framework/core/src/Flarum/Api/Actions/Base.php
@@ -26,7 +26,7 @@ abstract class Base extends Controller
     
     abstract protected function run();
 
-    public function handle($request, $parameters)
+    public function handle($request, $parameters = [])
     {
         $this->registerErrorHandlers();
 
@@ -39,6 +39,11 @@ abstract class Base extends Controller
         return $this->run();
     }
 
+    public function setRequest($request)
+    {
+        $this->request = $request;
+    }
+
     public function param($key, $default = null)
     {
         return array_get($this->parameters, $key, $default);
@@ -74,7 +79,7 @@ abstract class Base extends Controller
     protected function included($available)
     {
         $requested = explode(',', $this->input('include'));
-        return array_intersect($available, $requested);
+        return array_intersect((array) $available, $requested);
     }
 
     protected function explodeIds($ids)
diff --git a/framework/core/src/Flarum/Api/Actions/Discussions/Show.php b/framework/core/src/Flarum/Api/Actions/Discussions/Show.php
index 3b6e1238a..a5ad5e6d0 100644
--- a/framework/core/src/Flarum/Api/Actions/Discussions/Show.php
+++ b/framework/core/src/Flarum/Api/Actions/Discussions/Show.php
@@ -1,11 +1,32 @@
 <?php namespace Flarum\Api\Actions\Discussions;
 
 use Flarum\Core\Discussions\Discussion;
+use Flarum\Core\Posts\PostRepository;
 use Flarum\Api\Actions\Base;
+use Flarum\Api\Actions\Posts\GetsPostsForDiscussion;
 use Flarum\Api\Serializers\DiscussionSerializer;
 
 class Show extends Base
 {
+    use GetsPostsForDiscussion;
+
+    /**
+     * The post repository.
+     * 
+     * @var PostRepository
+     */
+    protected $posts;
+
+    /**
+     * Instantiate the action.
+     *
+     * @param PostRepository $posts
+     */
+    public function __construct(PostRepository $posts)
+    {
+        $this->posts = $posts;
+    }
+
     /**
      * Show a single discussion.
      *
@@ -13,10 +34,19 @@ class Show extends Base
      */
     protected function run()
     {
-        $include = $this->included(['startPost', 'lastPost']);
+        $include = $this->included(['startPost', 'lastPost', 'posts']);
 
         $discussion = Discussion::whereCanView()->findOrFail($this->param('id'));
 
+        if (in_array('posts', $include)) {
+            $relations = ['user', 'user.groups', 'editUser', 'deleteUser'];
+            $discussion->posts = $this->getPostsForDiscussion($this->posts, $discussion->id, $relations);
+
+            $include = array_merge($include, array_map(function ($relation) {
+                return 'posts.'.$relation;
+            }, $relations));
+        }
+
         // Set up the discussion serializer, which we will use to create the
         // document's primary resource. As well as including the requested
         // relations, we will specify that we want the 'posts' relation to be
diff --git a/framework/core/src/Flarum/Api/Actions/Posts/GetsPostsForDiscussion.php b/framework/core/src/Flarum/Api/Actions/Posts/GetsPostsForDiscussion.php
new file mode 100644
index 000000000..809f2bc7d
--- /dev/null
+++ b/framework/core/src/Flarum/Api/Actions/Posts/GetsPostsForDiscussion.php
@@ -0,0 +1,19 @@
+<?php namespace Flarum\Api\Actions\Posts;
+
+trait GetsPostsForDiscussion
+{
+	protected function getPostsForDiscussion($repository, $discussionId, $relations = [])
+	{
+		$sort = $this->sort(['time']);
+        $count = $this->count(20, 50);
+
+        if (($near = $this->input('near')) > 1) {
+            $start = $repository->getIndexForNumber($discussionId, $near);
+            $start = max(0, $start - $count / 2);
+        } else {
+            $start = 0;
+        }
+
+        return $repository->findByDiscussion($discussionId, $relations, $sort['by'], $sort['order'] ?: 'asc', $count, $start);
+	}
+}
diff --git a/framework/core/src/Flarum/Api/Actions/Posts/Index.php b/framework/core/src/Flarum/Api/Actions/Posts/Index.php
index 862e71dbb..8385fe458 100644
--- a/framework/core/src/Flarum/Api/Actions/Posts/Index.php
+++ b/framework/core/src/Flarum/Api/Actions/Posts/Index.php
@@ -2,11 +2,31 @@
 
 use Illuminate\Database\Eloquent\ModelNotFoundException;
 use Flarum\Core\Posts\Post;
+use Flarum\Core\Posts\PostRepository;
 use Flarum\Api\Actions\Base;
 use Flarum\Api\Serializers\PostSerializer;
 
 class Index extends Base
 {
+    use GetsPostsForDiscussion;
+
+    /**
+     * The post repository.
+     * 
+     * @var PostRepository
+     */
+    protected $posts;
+
+    /**
+     * Instantiate the action.
+     *
+     * @param PostRepository $posts
+     */
+    public function __construct(PostRepository $posts)
+    {
+        $this->posts = $posts;
+    }
+
     /**
      * Show posts from a discussion, or by providing an array of IDs.
 	 *
@@ -14,47 +34,16 @@ class Index extends Base
 	 */
     protected function run()
     {
-        $discussionId = $this->input('discussions');
         $postIds = (array) $this->input('ids');
+        $include = ['user', 'user.groups', 'editUser', 'deleteUser'];
 
-        $count = $this->count(20, 50);
-
-        if ($near = $this->input('near')) {
-            // fetch the nearest post
-            $post = Post::orderByRaw('ABS(CAST(number AS SIGNED) - ?)', [$near])->whereNotNull('number')->where('discussion_id', $discussionId)->take(1)->first();
-
-            $start = max(
-                0,
-                Post::whereCanView()
-                    ->where('discussion_id', $discussionId)
-                    ->where('time', '<=', $post->time)
-                    ->count() - round($count / 2)
-            );
-        } else {
-            $start = $this->start();
-        }
-
-        $include = $this->included([]);
-        $sort    = $this->sort(['time']);
-
-        $relations = array_merge(['user', 'user.groups', 'editUser', 'deleteUser'], $include);
-
-        // @todo move to post repository
-        $posts = Post::with($relations)
-            ->whereCanView();
-
-        if ($discussionId) {
-            $posts->where('discussion_id', $discussionId);
-        }
         if (count($postIds)) {
-            $posts->whereIn('id', $postIds);
+            $posts = $this->posts->findMany($postIds, $include);
+        } else {
+            $discussionId = $this->input('discussions');
+            $posts = $this->getPostsForDiscussion($this->posts, $discussionId, $include);
         }
 
-        $posts = $posts->skip($start)
-            ->take($count)
-            ->orderBy($sort['by'], $sort['order'] ?: 'asc')
-            ->get();
-
         if (! count($posts)) {
             throw new ModelNotFoundException;
         }
@@ -62,7 +51,7 @@ class Index extends Base
         // Finally, we can set up the post serializer and use it to create
         // a post resource or collection, depending on how many posts were
         // requested.
-        $serializer = new PostSerializer($relations);
+        $serializer = new PostSerializer($include);
         $this->document->setPrimaryElement($serializer->collection($posts));
 
         return $this->respondWithDocument();
diff --git a/framework/core/src/Flarum/Api/Serializers/DiscussionSerializer.php b/framework/core/src/Flarum/Api/Serializers/DiscussionSerializer.php
index 67032adde..764e23358 100644
--- a/framework/core/src/Flarum/Api/Serializers/DiscussionSerializer.php
+++ b/framework/core/src/Flarum/Api/Serializers/DiscussionSerializer.php
@@ -58,7 +58,8 @@ class DiscussionSerializer extends DiscussionBasicSerializer
     }
 
     /**
-     * Get a collection containing a discussion's viewable posts.
+     * Get a collection containing a discussion's viewable posts. Assumes that
+     * the discussion model's posts attributes has been filled.
      * 
      * @param Discussion $discussion
      * @param array $relations
@@ -66,7 +67,7 @@ class DiscussionSerializer extends DiscussionBasicSerializer
      */
     public function includePosts(Discussion $discussion, $relations)
     {
-        return (new PostSerializer($relations))->collection($discussion->posts()->whereCanView()->get());
+        return (new PostSerializer($relations))->collection($discussion->posts);
     }
 
     /**
diff --git a/framework/core/src/Flarum/Core/Posts/PostRepository.php b/framework/core/src/Flarum/Core/Posts/PostRepository.php
index 4fa42333a..8718fa829 100755
--- a/framework/core/src/Flarum/Core/Posts/PostRepository.php
+++ b/framework/core/src/Flarum/Core/Posts/PostRepository.php
@@ -18,6 +18,40 @@ class PostRepository
         return $query->findOrFail($id);
     }
 
+    public function getIndexForNumber($discussionId, $number)
+    {
+        return Post::whereCanView()
+            ->where('discussion_id', $discussionId)
+            ->where('time', '<', function ($query) use ($discussionId, $number) {
+                $query->select('time')
+                      ->from('posts')
+                      ->where('discussion_id', $discussionId)
+                      ->whereNotNull('number')
+                      ->orderByRaw('ABS(CAST(number AS SIGNED) - ?)', [$number])
+                      ->take(1);
+            })
+            ->count();
+    }
+
+    public function findByDiscussion($discussionId, $relations = [], $sortBy = 'time', $sortOrder = 'asc', $count = null, $start = 0)
+    {
+        return Post::with($relations)
+            ->whereCanView()
+            ->where('discussion_id', $discussionId)
+            ->skip($start)
+            ->take($count)
+            ->orderBy($sortBy, $sortOrder)
+            ->get();
+    }
+
+    public function findMany($ids, $relations = [])
+    {
+        return Post::with($relations)
+            ->whereCanView()
+            ->whereIn('id', $ids)
+            ->get();
+    }
+
     public function save(Post $post)
     {
         $post->assertValid();