Merge branch 'mia_backort' into 'master'

Backport of Multiple Assignees feature

See merge request !11089

14 files changed, 74 insertions, 40 deletions

diff --git a/lib/api/api.rb b/lib/api/api.rb
index 302ccd3e532..52cd7cbe3db 100644
--- a/lib/api/api.rb
+++ b/lib/api/api.rb
@@ -6,6 +6,7 @@ module API
 
     version 'v3', using: :path do
       helpers ::API::V3::Helpers
+      helpers ::API::Helpers::CommonHelpers
 
       mount ::API::V3::AwardEmoji
       mount ::API::V3::Boards
@@ -80,6 +81,7 @@ module API
     # Ensure the namespace is right, otherwise we might load Grape::API::Helpers
     helpers ::SentryHelper
     helpers ::API::Helpers
+    helpers ::API::Helpers::CommonHelpers
 
     # Keep in alphabetical order
     mount ::API::AccessRequests
diff --git a/lib/api/entities.rb b/lib/api/entities.rb
index 6d6ccefe877..f8f5548d23d 100644
--- a/lib/api/entities.rb
+++ b/lib/api/entities.rb
@@ -256,7 +256,11 @@ module API
     class IssueBasic < ProjectEntity
       expose :label_names, as: :labels
       expose :milestone, using: Entities::Milestone
-      expose :assignee, :author, using: Entities::UserBasic
+      expose :assignees, :author, using: Entities::UserBasic
+
+      expose :assignee, using: ::API::Entities::UserBasic do |issue, options|
+        issue.assignees.first
+      end
 
       expose :user_notes_count
       expose :upvotes, :downvotes
diff --git a/lib/api/helpers/common_helpers.rb b/lib/api/helpers/common_helpers.rb
new file mode 100644
index 00000000000..6236fdd43ca
--- /dev/null
+++ b/lib/api/helpers/common_helpers.rb
@@ -0,0 +1,13 @@
+module API
+  module Helpers
+    module CommonHelpers
+      def convert_parameters_from_legacy_format(params)
+        if params[:assignee_id].present?
+          params[:assignee_ids] = [params.delete(:assignee_id)]
+        end
+
+        params
+      end
+    end
+  end
+end
diff --git a/lib/api/issues.rb b/lib/api/issues.rb
index 522f0f3be92..78db960ae28 100644
--- a/lib/api/issues.rb
+++ b/lib/api/issues.rb
@@ -32,7 +32,8 @@ module API
 
       params :issue_params_ce do
         optional :description, type: String, desc: 'The description of an issue'
-        optional :assignee_id, type: Integer, desc: 'The ID of a user to assign issue'
+        optional :assignee_ids, type: Array[Integer], desc: 'The array of user IDs to assign issue'
+        optional :assignee_id,  type: Integer, desc: '[Deprecated] The ID of a user to assign issue'
         optional :milestone_id, type: Integer, desc: 'The ID of a milestone to assign issue'
         optional :labels, type: String, desc: 'Comma-separated list of label names'
         optional :due_date, type: String, desc: 'Date string in the format YEAR-MONTH-DAY'
@@ -135,6 +136,8 @@ module API
 
         issue_params = declared_params(include_missing: false)
 
+        issue_params = convert_parameters_from_legacy_format(issue_params)
+
         issue = ::Issues::CreateService.new(user_project,
                                             current_user,
                                             issue_params.merge(request: request, api: true)).execute
@@ -159,7 +162,7 @@ module API
                               desc: 'Date time when the issue was updated. Available only for admins and project owners.'
         optional :state_event, type: String, values: %w[reopen close], desc: 'State of the issue'
         use :issue_params
-        at_least_one_of :title, :description, :assignee_id, :milestone_id,
+        at_least_one_of :title, :description, :assignee_ids, :assignee_id, :milestone_id,
                         :labels, :created_at, :due_date, :confidential, :state_event
       end
       put ':id/issues/:issue_iid' do
@@ -173,6 +176,8 @@ module API
 
         update_params = declared_params(include_missing: false).merge(request: request, api: true)
 
+        update_params = convert_parameters_from_legacy_format(update_params)
+
         issue = ::Issues::UpdateService.new(user_project,
                                             current_user,
                                             update_params).execute(issue)
diff --git a/lib/api/v3/entities.rb b/lib/api/v3/entities.rb
index 832b4bdeb4f..7c8be7e51db 100644
--- a/lib/api/v3/entities.rb
+++ b/lib/api/v3/entities.rb
@@ -248,6 +248,13 @@ module API
         expose :project_id, :issues_events, :merge_requests_events
         expose :note_events, :build_events, :pipeline_events, :wiki_page_events
       end
+
+      class Issue < ::API::Entities::Issue
+        unexpose :assignees
+        expose :assignee do |issue, options|
+          ::API::Entities::UserBasic.represent(issue.assignees.first, options)
+        end
+      end
     end
   end
 end
diff --git a/lib/api/v3/issues.rb b/lib/api/v3/issues.rb
index 715083fc4f8..cb371fdbab8 100644
--- a/lib/api/v3/issues.rb
+++ b/lib/api/v3/issues.rb
@@ -8,6 +8,7 @@ module API
       helpers do
         def find_issues(args = {})
           args = params.merge(args)
+          args = convert_parameters_from_legacy_format(args)
 
           args.delete(:id)
           args[:milestone_title] = args.delete(:milestone)
@@ -51,7 +52,7 @@ module API
 
       resource :issues do
         desc "Get currently authenticated user's issues" do
-          success ::API::Entities::Issue
+          success ::API::V3::Entities::Issue
         end
         params do
           optional :state, type: String, values: %w[opened closed all], default: 'all',
@@ -61,7 +62,7 @@ module API
         get do
           issues = find_issues(scope: 'authored')
 
-          present paginate(issues), with: ::API::Entities::Issue, current_user: current_user
+          present paginate(issues), with: ::API::V3::Entities::Issue, current_user: current_user
         end
       end
 
@@ -70,7 +71,7 @@ module API
       end
       resource :groups, requirements: { id: %r{[^/]+} } do
         desc 'Get a list of group issues' do
-          success ::API::Entities::Issue
+          success ::API::V3::Entities::Issue
         end
         params do
           optional :state, type: String, values: %w[opened closed all], default: 'all',
@@ -82,7 +83,7 @@ module API
 
           issues = find_issues(group_id: group.id, match_all_labels: true)
 
-          present paginate(issues), with: ::API::Entities::Issue, current_user: current_user
+          present paginate(issues), with: ::API::V3::Entities::Issue, current_user: current_user
         end
       end
 
@@ -94,7 +95,7 @@ module API
 
         desc 'Get a list of project issues' do
           detail 'iid filter is deprecated have been removed on V4'
-          success ::API::Entities::Issue
+          success ::API::V3::Entities::Issue
         end
         params do
           optional :state, type: String, values: %w[opened closed all], default: 'all',
@@ -107,22 +108,22 @@ module API
 
           issues = find_issues(project_id: project.id)
 
-          present paginate(issues), with: ::API::Entities::Issue, current_user: current_user, project: user_project
+          present paginate(issues), with: ::API::V3::Entities::Issue, current_user: current_user, project: user_project
         end
 
         desc 'Get a single project issue' do
-          success ::API::Entities::Issue
+          success ::API::V3::Entities::Issue
         end
         params do
           requires :issue_id, type: Integer, desc: 'The ID of a project issue'
         end
         get ":id/issues/:issue_id" do
           issue = find_project_issue(params[:issue_id])
-          present issue, with: ::API::Entities::Issue, current_user: current_user, project: user_project
+          present issue, with: ::API::V3::Entities::Issue, current_user: current_user, project: user_project
         end
 
         desc 'Create a new project issue' do
-          success ::API::Entities::Issue
+          success ::API::V3::Entities::Issue
         end
         params do
           requires :title, type: String, desc: 'The title of an issue'
@@ -140,6 +141,7 @@ module API
 
           issue_params = declared_params(include_missing: false)
           issue_params = issue_params.merge(merge_request_to_resolve_discussions_of: issue_params.delete(:merge_request_for_resolving_discussions))
+          issue_params = convert_parameters_from_legacy_format(issue_params)
 
           issue = ::Issues::CreateService.new(user_project,
                                               current_user,
@@ -147,14 +149,14 @@ module API
           render_spam_error! if issue.spam?
 
           if issue.valid?
-            present issue, with: ::API::Entities::Issue, current_user: current_user, project: user_project
+            present issue, with: ::API::V3::Entities::Issue, current_user: current_user, project: user_project
           else
             render_validation_error!(issue)
           end
         end
 
         desc 'Update an existing issue' do
-          success ::API::Entities::Issue
+          success ::API::V3::Entities::Issue
         end
         params do
           requires :issue_id, type: Integer, desc: 'The ID of a project issue'
@@ -176,6 +178,7 @@ module API
           end
 
           update_params = declared_params(include_missing: false).merge(request: request, api: true)
+          update_params = convert_parameters_from_legacy_format(update_params)
 
           issue = ::Issues::UpdateService.new(user_project,
                                               current_user,
@@ -184,14 +187,14 @@ module API
           render_spam_error! if issue.spam?
 
           if issue.valid?
-            present issue, with: ::API::Entities::Issue, current_user: current_user, project: user_project
+            present issue, with: ::API::V3::Entities::Issue, current_user: current_user, project: user_project
           else
             render_validation_error!(issue)
           end
         end
 
         desc 'Move an existing issue' do
-          success ::API::Entities::Issue
+          success ::API::V3::Entities::Issue
         end
         params do
           requires :issue_id, type: Integer, desc: 'The ID of a project issue'
@@ -206,7 +209,7 @@ module API
 
           begin
             issue = ::Issues::MoveService.new(user_project, current_user).execute(issue, new_project)
-            present issue, with: ::API::Entities::Issue, current_user: current_user, project: user_project
+            present issue, with: ::API::V3::Entities::Issue, current_user: current_user, project: user_project
           rescue ::Issues::MoveService::MoveError => error
             render_api_error!(error.message, 400)
           end
diff --git a/lib/api/v3/merge_requests.rb b/lib/api/v3/merge_requests.rb
index 1616142a619..b6b7254ae29 100644
--- a/lib/api/v3/merge_requests.rb
+++ b/lib/api/v3/merge_requests.rb
@@ -34,7 +34,7 @@ module API
             if project.has_external_issue_tracker?
               ::API::Entities::ExternalIssue
             else
-              ::API::Entities::Issue
+              ::API::V3::Entities::Issue
             end
           end
 
diff --git a/lib/api/v3/milestones.rb b/lib/api/v3/milestones.rb
index be90cec4afc..4c7061d4939 100644
--- a/lib/api/v3/milestones.rb
+++ b/lib/api/v3/milestones.rb
@@ -39,7 +39,7 @@ module API
         end
 
         desc 'Get all issues for a single project milestone' do
-          success ::API::Entities::Issue
+          success ::API::V3::Entities::Issue
         end
         params do
           requires :milestone_id, type: Integer, desc: 'The ID of a project milestone'
@@ -56,7 +56,7 @@ module API
           }
 
           issues = IssuesFinder.new(current_user, finder_params).execute
-          present paginate(issues), with: ::API::Entities::Issue, current_user: current_user, project: user_project
+          present paginate(issues), with: ::API::V3::Entities::Issue, current_user: current_user, project: user_project
         end
       end
     end
diff --git a/lib/banzai/reference_parser/issue_parser.rb b/lib/banzai/reference_parser/issue_parser.rb
index e02b360924a..89ec715ddf6 100644
--- a/lib/banzai/reference_parser/issue_parser.rb
+++ b/lib/banzai/reference_parser/issue_parser.rb
@@ -28,7 +28,7 @@ module Banzai
           nodes,
           Issue.all.includes(
             :author,
-            :assignee,
+            :assignees,
             {
               # These associations are primarily used for checking permissions.
               # Eager loading these ensures we don't end up running dozens of
diff --git a/lib/github/import.rb b/lib/github/import.rb
index d49761fd6c6..06beb607a3e 100644
--- a/lib/github/import.rb
+++ b/lib/github/import.rb
@@ -245,7 +245,7 @@ module Github
               issue.label_ids    = label_ids(representation.labels)
               issue.milestone_id = milestone_id(representation.milestone)
               issue.author_id    = author_id
-              issue.assignee_id  = user_id(representation.assignee)
+              issue.assignee_ids = [user_id(representation.assignee)]
               issue.created_at   = representation.created_at
               issue.updated_at   = representation.updated_at
               issue.save!(validate: false)
diff --git a/lib/gitlab/chat_commands/presenters/issue_base.rb b/lib/gitlab/chat_commands/presenters/issue_base.rb
index 054f7f4be0c..25bc82994ba 100644
--- a/lib/gitlab/chat_commands/presenters/issue_base.rb
+++ b/lib/gitlab/chat_commands/presenters/issue_base.rb
@@ -22,7 +22,7 @@ module Gitlab
           [
             {
               title: "Assignee",
-              value: @resource.assignee ? @resource.assignee.name : "_None_",
+              value: @resource.assignees.any? ? @resource.assignees.first.name : "_None_",
               short: true
             },
             {
diff --git a/lib/gitlab/fogbugz_import/importer.rb b/lib/gitlab/fogbugz_import/importer.rb
index 222bcdcbf9c..3dcee681c72 100644
--- a/lib/gitlab/fogbugz_import/importer.rb
+++ b/lib/gitlab/fogbugz_import/importer.rb
@@ -122,15 +122,15 @@ module Gitlab
           author_id = user_info(bug['ixPersonOpenedBy'])[:gitlab_id] || project.creator_id
 
           issue = Issue.create!(
-            iid:         bug['ixBug'],
-            project_id:  project.id,
-            title:       bug['sTitle'],
-            description: body,
-            author_id:   author_id,
-            assignee_id: assignee_id,
-            state:       bug['fOpen'] == 'true' ? 'opened' : 'closed',
-            created_at:  date,
-            updated_at:  DateTime.parse(bug['dtLastUpdated'])
+            iid:          bug['ixBug'],
+            project_id:   project.id,
+            title:        bug['sTitle'],
+            description:  body,
+            author_id:    author_id,
+            assignee_ids: [assignee_id],
+            state:        bug['fOpen'] == 'true' ? 'opened' : 'closed',
+            created_at:   date,
+            updated_at:   DateTime.parse(bug['dtLastUpdated'])
           )
 
           issue_labels = ::LabelsFinder.new(nil, project_id: project.id, title: labels).execute(skip_authorization: true)
diff --git a/lib/gitlab/github_import/issue_formatter.rb b/lib/gitlab/github_import/issue_formatter.rb
index 6f5ac4dac0d..977cd0423ba 100644
--- a/lib/gitlab/github_import/issue_formatter.rb
+++ b/lib/gitlab/github_import/issue_formatter.rb
@@ -10,7 +10,7 @@ module Gitlab
           description: description,
           state: state,
           author_id: author_id,
-          assignee_id: assignee_id,
+          assignee_ids: Array(assignee_id),
           created_at: raw_data.created_at,
           updated_at: raw_data.updated_at
         }
diff --git a/lib/gitlab/google_code_import/importer.rb b/lib/gitlab/google_code_import/importer.rb
index 5ca3e6a95ca..1b43440673c 100644
--- a/lib/gitlab/google_code_import/importer.rb
+++ b/lib/gitlab/google_code_import/importer.rb
@@ -108,13 +108,13 @@ module Gitlab
           end
 
           issue = Issue.create!(
-            iid:         raw_issue['id'],
-            project_id:  project.id,
-            title:       raw_issue['title'],
-            description: body,
-            author_id:   project.creator_id,
-            assignee_id: assignee_id,
-            state:       raw_issue['state'] == 'closed' ? 'closed' : 'opened'
+            iid:          raw_issue['id'],
+            project_id:   project.id,
+            title:        raw_issue['title'],
+            description:  body,
+            author_id:    project.creator_id,
+            assignee_ids: [assignee_id],
+            state:        raw_issue['state'] == 'closed' ? 'closed' : 'opened'
           )
 
           issue_labels = ::LabelsFinder.new(nil, project_id: project.id, title: labels).execute(skip_authorization: true)