Only use boolean parameters internally

Use internally only boolean params.

app/controllers/concerns/issuable_collections.rb

@@ -91,7 +91,7 @@ module IssuableCollections
     options = {
       scope: params[:scope],
       state: params[:state],
-      confidential: params[:confidential],
+      confidential: Gitlab::Utils.to_boolean(params[:confidential]),
       sort: set_sort_order
     }
 

app/finders/issues_finder.rb

@@ -69,14 +69,16 @@ class IssuesFinder < IssuableFinder
   end
 
   def filter_items(items)
-    issues = by_due_date(super)
-    by_confidential(issues)
+    issues = super
+    issues = by_due_date(issues)
+    issues = by_confidential(issues)
+    issues
   end
 
   def by_confidential(items)
-    return items unless params[:confidential].present?
+    return items if params[:confidential].nil?
 
-    params[:confidential] == 'yes' ? items.confidential_only : items.public_only
+    params[:confidential] ? items.confidential_only : items.public_only
   end
 
   def by_due_date(items)

lib/api/issues.rb

@@ -15,14 +15,6 @@ module API
 
       params :issue_params_ee do
       end
-
-      def convert_confidential_param(args)
-        confidential = args.delete(:confidential)
-        return args if confidential.nil?
-
-        args[:confidential] = confidential ? 'yes' : 'no'
-        args
-      end
     end
 
     helpers do
@@ -34,7 +26,6 @@ module API
         args[:milestone_title] = args.delete(:milestone)
         args[:label_name] = args.delete(:labels)
         args[:scope] = args[:scope].underscore if args[:scope]
-        args = convert_confidential_param(args)
 
         issues = IssuesFinder.new(current_user, args).execute
           .preload(:assignees, :labels, :notes, :timelogs, :project, :author, :closed_by)

spec/controllers/concerns/issuable_collections_spec.rb

@@ -112,8 +112,8 @@ describe IssuableCollections do
         assignee_username: 'user1',
         author_id: '2',
         author_username: 'user2',
-        authorized_only: 'true',
-        confidential: 'yes',
+        authorized_only: 'yes',
+        confidential: true,
         due_date: '2017-01-01',
         group_id: '3',
         iids: '4',
@@ -141,7 +141,7 @@ describe IssuableCollections do
         'assignee_username' => 'user1',
         'author_id' => '2',
         'author_username' => 'user2',
-        'confidential' => 'yes',
+        'confidential' => true,
         'label_name' => 'foo',
         'milestone_title' => 'bar',
         'my_reaction_emoji' => 'thumbsup',

spec/finders/issues_finder_spec.rb

@@ -470,7 +470,7 @@ describe IssuesFinder do
         end
 
         context 'user filters confidential issues' do
-          let(:params) { { confidential: 'yes' } }
+          let(:params) { { confidential: true } }
 
           it 'returns only confdential issues' do
             expect(issues).to contain_exactly(confidential_issue)
@@ -478,7 +478,7 @@ describe IssuesFinder do
         end
 
         context 'user filters only public issues' do
-          let(:params) { { confidential: 'no' } }
+          let(:params) { { confidential: false } }
 
           it 'returns only confdential issues' do
             expect(issues).to contain_exactly(issue1, issue2, issue3, issue4)