Add merge request count to each issue on issues list

app/assets/images/icon-merge-request-unmerged.svg

+<svg width="12" height="15" viewBox="0 0 12 15" xmlns="http://www.w3.org/2000/svg"><path d="M10.267 11.028V5.167c-.028-.728-.318-1.372-.878-1.923-.56-.55-1.194-.85-1.922-.877h-.934V.5l-2.8 2.8 2.8 2.8V4.233h.934a.976.976 0 0 1 .644.29.88.88 0 0 1 .289.644v5.861a1.86 1.86 0 0 0 .933 3.472 1.86 1.86 0 0 0 .934-3.472zM3.733 3.3a1.86 1.86 0 0 0-1.866-1.867 1.86 1.86 0 0 0-.934 3.472v6.123a1.86 1.86 0 0 0 .933 3.472 1.86 1.86 0 0 0 .934-3.472V4.905c.55-.317.933-.914.933-1.605z" fill-rule="nonzero"/></svg>

app/assets/stylesheets/pages/issues.scss

@@ -10,6 +10,11 @@
     .issue-labels {
       display: inline-block;
     }
+
+    .icon-merge-request-unmerged {
+      height: 13px;
+      margin-bottom: 3px;
+     }
   }
 }

app/controllers/concerns/issuable_collections.rb

@@ -9,24 +9,32 @@ module IssuableCollections
   private
-  def issuable_meta_data(issuable_collection)
+  def issuable_meta_data(issuable_collection, collection_type)
     # map has to be used here since using pluck or select will
     # throw an error when ordering issuables by priority which inserts
     # a new order into the collection.
     # We cannot use reorder to not mess up the paginated collection.
-    issuable_ids         = issuable_collection.map(&:id)
-    issuable_note_count  = Note.count_for_collection(issuable_ids, @collection_type)
+    issuable_ids = issuable_collection.map(&:id)
+    issuable_note_count = Note.count_for_collection(issuable_ids, @collection_type)
     issuable_votes_count = AwardEmoji.votes_for_collection(issuable_ids, @collection_type)
+    issuable_merge_requests_count =
+      if collection_type == 'Issue'
+        MergeRequestsClosingIssues.count_for_collection(issuable_ids)
+      else
+        []
+      end
     issuable_ids.each_with_object({}) do |id, issuable_meta|
       downvotes = issuable_votes_count.find { |votes| votes.awardable_id == id && votes.downvote? }
-      upvotes   = issuable_votes_count.find { |votes| votes.awardable_id == id && votes.upvote? }
-      notes     = issuable_note_count.find  { |notes| notes.noteable_id == id }
+      upvotes = issuable_votes_count.find { |votes| votes.awardable_id == id && votes.upvote? }
+      notes = issuable_note_count.find { |notes| notes.noteable_id == id }
+      merge_requests = issuable_merge_requests_count.find { |mr| mr.issue_id == id }
       issuable_meta[id] = Issuable::IssuableMeta.new(
         upvotes.try(:count).to_i,
         downvotes.try(:count).to_i,
-        notes.try(:count).to_i
+        notes.try(:count).to_i,
+        merge_requests.try(:count).to_i
       )
     end
   end

app/controllers/concerns/issues_action.rb

@@ -10,7 +10,7 @@ module IssuesAction
               .page(params[:page])
     @collection_type    = "Issue"
-    @issuable_meta_data = issuable_meta_data(@issues)
+    @issuable_meta_data = issuable_meta_data(@issues, @collection_type)
     respond_to do |format|
       format.html

app/controllers/concerns/merge_requests_action.rb

@@ -9,7 +9,7 @@ module MergeRequestsAction
                       .page(params[:page])
     @collection_type    = "MergeRequest"
-    @issuable_meta_data = issuable_meta_data(@merge_requests)
+    @issuable_meta_data = issuable_meta_data(@merge_requests, @collection_type)
   end
   private

app/controllers/projects/issues_controller.rb

@@ -26,7 +26,7 @@ class Projects::IssuesController < Projects::ApplicationController
     @collection_type    = "Issue"
     @issues             = issues_collection
     @issues             = @issues.page(params[:page])
-    @issuable_meta_data = issuable_meta_data(@issues)
+    @issuable_meta_data = issuable_meta_data(@issues, @collection_type)
     if @issues.out_of_range? && @issues.total_pages != 0
       return redirect_to url_for(params.merge(page: @issues.total_pages))

app/controllers/projects/merge_requests_controller.rb

@@ -39,7 +39,7 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     @collection_type    = "MergeRequest"
     @merge_requests     = merge_requests_collection
     @merge_requests     = @merge_requests.page(params[:page])
-    @issuable_meta_data = issuable_meta_data(@merge_requests)
+    @issuable_meta_data = issuable_meta_data(@merge_requests, @collection_type)
     if @merge_requests.out_of_range? && @merge_requests.total_pages != 0
       return redirect_to url_for(params.merge(page: @merge_requests.total_pages))

app/models/concerns/issuable.rb

@@ -16,9 +16,9 @@ module Issuable
   include TimeTrackable
   # This object is used to gather issuable meta data for displaying
-  # upvotes, downvotes and notes count for issues and merge requests
+  # upvotes, downvotes, notes and closing merge requests count for issues and merge requests
   # lists avoiding n+1 queries and improving performance.
-  IssuableMeta = Struct.new(:upvotes, :downvotes, :notes_count)
+  IssuableMeta = Struct.new(:upvotes, :downvotes, :notes_count, :merge_requests_count)
   included do
     cache_markdown_field :title, pipeline: :single_line

app/models/merge_requests_closing_issues.rb

@@ -4,4 +4,12 @@ class MergeRequestsClosingIssues < ActiveRecord::Base
   validates :merge_request_id, uniqueness: { scope: :issue_id }, presence: true
   validates :issue_id, presence: true
+
+  class << self
+    def count_for_collection(ids)
+      select('issue_id', 'COUNT(*) as count').
+        group(:issue_id).
+        where(issue_id: ids)
+    end
+  end
 end

app/views/shared/_issuable_meta_data.html.haml

@@ -2,6 +2,12 @@
 - issue_votes        = @issuable_meta_data[issuable.id]
 - upvotes, downvotes = issue_votes.upvotes, issue_votes.downvotes
 - issuable_url       = @collection_type == "Issue" ? issue_path(issuable, anchor: 'notes') : merge_request_path(issuable, anchor: 'notes')
+- issuable_mr        = @issuable_meta_data[issuable.id].merge_requests_count
+
+- if issuable_mr > 0
+  %li
+    = image_tag('icon-merge-request-unmerged', class: 'icon-merge-request-unmerged')
+    = issuable_mr
 - if upvotes > 0
   %li

changelogs/unreleased/add_mr_info_to_issues_list.yml

+---
+title: Add merge request count to each issue on issues list
+merge_request: 9252
+author: blackst0ne