FEATURE: per-category default topic list sort order

app/assets/javascripts/discourse/components/edit-category-settings.js.es6

@@ -1,7 +1,25 @@
 import { setting } from 'discourse/lib/computed';
 import { buildCategoryPanel } from 'discourse/components/edit-category-panel';
+import computed from "ember-addons/ember-computed-decorators";
 
 export default buildCategoryPanel('settings', {
   emailInEnabled: setting('email_in'),
   showPositionInput: setting('fixed_category_positions'),
+
+  isDefaultSortOrder: Em.computed.empty('category.sort_order'),
+
+  @computed
+  availableSorts() {
+    return ['likes', 'op_likes', 'views', 'posts', 'activity', 'posters', 'category', 'created']
+      .map(s => ({ name: I18n.t('category.sort_options.' + s), value: s }))
+      .sort((a,b) => { return a.name > b.name; });
+  },
+
+  @computed
+  sortAscendingOptions() {
+    return [
+      {name: I18n.t('category.sort_ascending'),  value: 'true'},
+      {name: I18n.t('category.sort_descending'), value: 'false'}
+    ];
+  }
 });

app/assets/javascripts/discourse/models/category.js.es6

@@ -98,7 +98,9 @@ const Category = RestModel.extend({
         topic_template: this.get('topic_template'),
         suppress_from_homepage: this.get('suppress_from_homepage'),
         allowed_tags: this.get('allowed_tags'),
-        allowed_tag_groups: this.get('allowed_tag_groups')
+        allowed_tag_groups: this.get('allowed_tag_groups'),
+        sort_order: this.get('sort_order'),
+        sort_ascending: this.get('sort_ascending')
       },
       type: id ? 'PUT' : 'POST'
     });

app/assets/javascripts/discourse/templates/components/edit-category-settings.hbs

@@ -19,6 +19,16 @@
   </label>
 </section>
 
+<section class="field">
+  <label>
+    {{i18n "category.sort_order"}}
+    {{combo-box valueAttribute="value" content=availableSorts value=category.sort_order none="category.sort_options.default"}}
+    {{#unless isDefaultSortOrder}}
+      {{combo-box valueAttribute="value" content=sortAscendingOptions value=category.sort_ascending none="category.sort_options.default"}}
+    {{/unless}}
+  </label>
+</section>
+
 {{#if emailInEnabled}}
     <section class='field'>
       <label>

app/controllers/categories_controller.rb

@@ -238,6 +238,8 @@ class CategoriesController < ApplicationController
                         :slug,
                         :allow_badges,
                         :topic_template,
+                        :sort_order,
+                        :sort_ascending,
                         :custom_fields => [params[:custom_fields].try(:keys)],
                         :permissions => [*p.try(:keys)],
                         :allowed_tags => [],

app/models/category.rb

@@ -536,6 +536,8 @@ end
 #  topic_template                :text
 #  suppress_from_homepage        :boolean          default(FALSE)
 #  contains_messages             :boolean
+#  sort_order                    :string
+#  sort_ascending                :boolean
 #
 # Indexes
 #

app/serializers/basic_category_serializer.rb

@@ -19,7 +19,9 @@ class BasicCategorySerializer < ApplicationSerializer
              :notification_level,
              :can_edit,
              :topic_template,
-             :has_children
+             :has_children,
+             :sort_order,
+             :sort_ascending
 
   def include_parent_category_id?
     parent_category_id