FIX: categories with non-ascii names will have broken next page urls

app/controllers/list_controller.rb

@@ -104,9 +104,9 @@ class ListController < ApplicationController
     discourse_expires_in 1.minute
 
     @title = @category.name
-    @link = "#{Discourse.base_url}/category/#{@category.slug}"
+    @link = "#{Discourse.base_url}/category/#{@category.slug_for_url}"
     @description = "#{I18n.t('topics_in_category', category: @category.name)} #{@category.description}"
-    @atom_link = "#{Discourse.base_url}/category/#{@category.slug}.rss"
+    @atom_link = "#{Discourse.base_url}/category/#{@category.slug_for_url}.rss"
     @topic_list = TopicQuery.new.list_new_in_category(@category)
 
     render 'list', formats: [:rss]
@@ -222,8 +222,8 @@ class ListController < ApplicationController
   def page_params(opts = nil)
     opts ||= {}
     route_params = {format: 'json'}
-    route_params[:category]        = @category.slug if @category
+    route_params[:category]        = @category.slug_for_url if @category
-    route_params[:parent_category] = @category.parent_category.slug if @category && @category.parent_category
+    route_params[:parent_category] = @category.parent_category.slug_for_url if @category && @category.parent_category
     route_params[:sort_order]      = opts[:sort_order] if opts[:sort_order].present?
     route_params[:sort_descending] = opts[:sort_descending] if opts[:sort_descending].present?
     route_params

app/models/category.rb

@@ -186,6 +186,10 @@ SQL
     end
   end
 
+  def slug_for_url
+    slug.present? ? self.slug : "#{self.id}-category"
+  end
+
   def publish_categories_list
     MessageBus.publish('/categories', {categories: ActiveModel::ArraySerializer.new(Category.latest).as_json})
   end

spec/models/category_spec.rb

@@ -150,6 +150,7 @@ describe Category do
 
     it "creates a blank slug, this is OK." do
       category.slug.should be_blank
+      category.slug_for_url.should == "#{category.id}-category"
     end
   end
 
@@ -158,6 +159,7 @@ describe Category do
 
     it 'creates a blank slug' do
       category.slug.should be_blank
+      category.slug_for_url.should == "#{category.id}-category"
     end
   end
 
@@ -169,6 +171,7 @@ describe Category do
 
     it 'is created correctly' do
       @category.slug.should == 'amazing-category'
+      @category.slug_for_url.should == @category.slug
 
       @category.description.should be_blank
 
@@ -204,7 +207,9 @@ describe Category do
 
     describe "creating a new category with the same slug" do
       it "should have a blank slug" do
-        Fabricate(:category, name: "Amazing Categóry").slug.should be_blank
+        category = Fabricate(:category, name: "Amazing Categóry")
+        category.slug.should be_blank
+        category.slug_for_url.should == "#{category.id}-category"
       end
     end