Merge branch 'issue_18135' into 'master'

Todos sorting dropdown

Implements #18135 

![todos_sorting](/uploads/bff76827c421628134dfb8b864e47c74/todos_sorting.png)  


- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5691

2 files changed, 18 insertions, 15 deletions

diff --git a/app/models/concerns/issuable.rb b/app/models/concerns/issuable.rb
index cbae1cd439b..afb5ce37c06 100644
--- a/app/models/concerns/issuable.rb
+++ b/app/models/concerns/issuable.rb
@@ -131,7 +131,10 @@ module Issuable
     end
 
     def order_labels_priority(excluded_labels: [])
-      select("#{table_name}.*, (#{highest_label_priority(excluded_labels).to_sql}) AS highest_priority").
+      condition_field = "#{table_name}.id"
+      highest_priority = highest_label_priority(name, condition_field, excluded_labels: excluded_labels).to_sql
+
+      select("#{table_name}.*, (#{highest_priority}) AS highest_priority").
         group(arel_table[:id]).
         reorder(Gitlab::Database.nulls_last_order('highest_priority', 'ASC'))
     end
@@ -159,20 +162,6 @@ module Issuable
 
       grouping_columns
     end
-
-    private
-
-    def highest_label_priority(excluded_labels)
-      query = Label.select(Label.arel_table[:priority].minimum).
-        joins(:label_links).
-        where(label_links: { target_type: name }).
-        where("label_links.target_id = #{table_name}.id").
-        reorder(nil)
-
-      query.where.not(title: excluded_labels) if excluded_labels.present?
-
-      query
-    end
   end
 
   def today?
diff --git a/app/models/concerns/sortable.rb b/app/models/concerns/sortable.rb
index 8b47b9e0abd..1ebecd86af9 100644
--- a/app/models/concerns/sortable.rb
+++ b/app/models/concerns/sortable.rb
@@ -35,5 +35,19 @@ module Sortable
         all
       end
     end
+
+    private
+
+    def highest_label_priority(object_types, condition_field, excluded_labels: [])
+      query = Label.select(Label.arel_table[:priority].minimum).
+        joins(:label_links).
+        where(label_links: { target_type: object_types }).
+        where("label_links.target_id = #{condition_field}").
+        reorder(nil)
+
+      query.where.not(title: excluded_labels) if excluded_labels.present?
+
+      query
+    end
   end
 end