Issuable#labels_hash works with with_label([]) to fix CSV export

app/models/concerns/issuable.rb

@@ -205,9 +205,12 @@ module Issuable
 
     def labels_hash
       issue_labels = Hash.new { |h, k| h[k] = [] }
-      eager_load(:labels).pluck(:id, 'labels.title').each do |issue_id, label|
+
+      relation = unscoped.where(id: self.select(:id)).eager_load(:labels)
+      relation.pluck(:id, 'labels.title').each do |issue_id, label|
         issue_labels[issue_id] << label
       end
+
       issue_labels
     end
 

changelogs/unreleased-ee/jej-fix-csv-export-filter-by-multiple-labels.yml

+---
+title: Fix CSV export when filtering issues by multiple labels
+merge_request: 2852
+author:
+type: fixed

spec/models/concerns/issuable_spec.rb

@@ -328,11 +328,18 @@ describe Issuable do
 
   describe '.labels_hash' do
     let(:feature_label) { create(:label, title: 'Feature') }
-    let!(:issues) { create_list(:labeled_issue, 3, labels: [feature_label]) }
+    let(:second_label) { create(:label, title: 'Second Label') }
+    let!(:issues) { create_list(:labeled_issue, 3, labels: [feature_label, second_label]) }
+    let(:issue_id) { issues.first.id }
 
     it 'maps issue ids to labels titles' do
-      issue_id = issues.first.id
-      expect(Issue.labels_hash[issue_id]).to eq ['Feature']
+      expect(Issue.labels_hash[issue_id]).to include('Feature')
+    end
+
+    it 'works on relations filtered by multiple labels' do
+      relation = Issue.with_label(['Feature', 'Second Label'])
+
+      expect(relation.labels_hash[issue_id]).to include('Feature', 'Second Label')
     end
   end