List subcategories on categories page

app/assets/javascripts/discourse/models/category_list.js

@@ -34,6 +34,10 @@ Discourse.CategoryList.reopenClass({
         c.parentCategory = list.findBy('id', c.parent_category_id);
       }
 
+      if (c.subcategory_ids) {
+        c.subcategories = c.subcategory_ids.map(function(scid) { return list.findBy('id', parseInt(scid, 10)); });
+      }
+
       if (c.featured_user_ids) {
         c.featured_users = c.featured_user_ids.map(function(u) {
           return users[u];

app/assets/javascripts/discourse/routes/list_categories_route.js

@@ -26,7 +26,7 @@ Discourse.ListCategoriesRoute = Discourse.Route.extend({
 
   model: function() {
     var listTopicsController = this.controllerFor('listTopics');
-    if (listTopicsController) listTopicsController.set('content', null);
+    if (listTopicsController) { listTopicsController.set('content', null); }
     return this.controllerFor('list').load('categories');
   },
 

app/assets/javascripts/discourse/templates/featured_topics.js.handlebars

@@ -56,6 +56,19 @@
     </tr>
   {{/each}}
 
+  {{#if subcategories}}
+    <tr>
+      <td>
+        <div class='subcategories'>
+          {{i18n categories.subcategories}}
+          {{#each subcategory in subcategories}}
+            {{categoryLink subcategory}}
+          {{/each}}
+        </div>
+      </td>
+    </tr>
+  {{/if}}
+
 </table>
 <footer class="clearfix">
   <figure title="{{i18n year_desc}}">{{number topics_year}} <figcaption>{{i18n category.this_year}}</figcaption></figure>

app/assets/javascripts/discourse/templates/list/wide_categories.js.handlebars

@@ -37,6 +37,15 @@
               {{{description_excerpt}}}
             </div>
           {{/if}}
+
+          {{#if subcategories}}
+            <div class='subcategories'>
+              {{i18n categories.subcategories}}
+              {{#each subcategory in subcategories}}
+                {{categoryLink subcategory}}
+              {{/each}}
+            </div>
+          {{/if}}
         </td>
         <td class='num'>{{number topic_count}}</td>
         <td class='num'>{{number post_count}}</td>

app/assets/stylesheets/desktop/topic-list.scss

@@ -235,9 +235,23 @@
   tbody td {
     padding-bottom: 20px;
   }
+
+  td.category {
+    padding-top: 15px;
+  }
+
   .category{
     position: relative;
     width: 55%;
+
+    .subcategories {
+      margin-top: 10px;
+      .badge-category {
+        font-size: 12px;
+        padding: 4px;
+      }
+    }
+
     .featured-users {
       position: absolute;
       right: 18px;
@@ -287,7 +301,7 @@
   #topic-list tbody tr:nth-child(even) {
     background-color: $white;
   }
-  .badge-category {
+  th .badge-category {
     float: left;
     margin: 1px 4px 0 0;
   }

app/models/category.rb

@@ -75,7 +75,7 @@ class Category < ActiveRecord::Base
 
   # permission is just used by serialization
   # we may consider wrapping this in another spot
-  attr_accessor :displayable_topics, :permission
+  attr_accessor :displayable_topics, :permission, :subcategory_ids
 
 
   def self.scoped_to_permissions(guardian, permission_types)

app/models/category_list.rb

@@ -61,6 +61,23 @@ class CategoryList
 
       @categories = @categories.to_a
 
+      subcategories = {}
+      to_delete = Set.new
+      @categories.each do |c|
+        if c.parent_category_id.present?
+          subcategories[c.parent_category_id] ||= []
+          subcategories[c.parent_category_id] << c.id
+          to_delete << c
+        end
+      end
+
+      if subcategories.present?
+        @categories.each do |c|
+          c.subcategory_ids = subcategories[c.id]
+        end
+        @categories.delete_if {|c| to_delete.include?(c) }
+      end
+
       if latest_post_only?
         @all_topics = []
         @categories.each do |c|

app/serializers/category_detailed_serializer.rb

@@ -5,7 +5,8 @@ class CategoryDetailedSerializer < BasicCategorySerializer
              :topics_month,
              :topics_year,
              :description_excerpt,
-             :is_uncategorized
+             :is_uncategorized,
+             :subcategory_ids
 
   has_many :featured_users, serializer: BasicUserSerializer
   has_many :displayable_topics, serializer: ListableTopicSerializer, embed: :objects, key: :topics
@@ -38,4 +39,8 @@ class CategoryDetailedSerializer < BasicCategorySerializer
     PrettyText.excerpt(description,300) if description
   end
 
+  def include_subcategory_ids?
+    subcategory_ids.present?
+  end
+
 end

config/locales/client.en.yml

@@ -192,6 +192,7 @@ en:
       latest: "Latest"
       latest_by: "latest by"
       toggle_ordering: "toggle ordering control"
+      subcategories: "Subcategories:"
 
     user:
       said: "{{username}} said:"