[CE] Support multiple assignees for merge requestsosw-multi-assignees-merge-requests

Backports https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/10161
(code out of ee/ folder).

5 files changed, 14 insertions, 9 deletions

diff --git a/lib/api/entities.rb b/lib/api/entities.rb
index 2dd3120d3fc..8e0623887a8 100644
--- a/lib/api/entities.rb
+++ b/lib/api/entities.rb
@@ -663,7 +663,11 @@ module API
       expose(:user_notes_count) { |merge_request, options| issuable_metadata(merge_request, options, :user_notes_count) }
       expose(:upvotes)          { |merge_request, options| issuable_metadata(merge_request, options, :upvotes) }
       expose(:downvotes)        { |merge_request, options| issuable_metadata(merge_request, options, :downvotes) }
-      expose :author, :assignee, using: Entities::UserBasic
+      expose :assignee, using: ::API::Entities::UserBasic do |merge_request|
+        merge_request.assignee
+      end
+      expose :author, :assignees, using: Entities::UserBasic
+
       expose :source_project_id, :target_project_id
       expose :labels do |merge_request|
         # Avoids an N+1 query since labels are preloaded
diff --git a/lib/api/merge_requests.rb b/lib/api/merge_requests.rb
index e4b21b7d1c4..1cc0ecc6df8 100644
--- a/lib/api/merge_requests.rb
+++ b/lib/api/merge_requests.rb
@@ -20,6 +20,7 @@ module API
     def self.update_params_at_least_one_of
       %i[
         assignee_id
+        assignee_ids
         description
         labels
         milestone_id
@@ -184,6 +185,7 @@ module API
         params :optional_params do
           optional :description, type: String, desc: 'The description of the merge request'
           optional :assignee_id, type: Integer, desc: 'The ID of a user to assign the merge request'
+          optional :assignee_ids, type: Array[Integer], desc: 'The array of user IDs to assign issue'
           optional :milestone_id, type: Integer, desc: 'The ID of a milestone to assign the merge request'
           optional :labels, type: Array[String], coerce_with: Validations::Types::LabelsList.coerce, desc: 'Comma-separated list of label names'
           optional :remove_source_branch, type: Boolean, desc: 'Remove source branch when merging'
@@ -231,6 +233,7 @@ module API
 
         mr_params = declared_params(include_missing: false)
         mr_params[:force_remove_source_branch] = mr_params.delete(:remove_source_branch)
+        mr_params = convert_parameters_from_legacy_format(mr_params)
 
         merge_request = ::MergeRequests::CreateService.new(user_project, current_user, mr_params).execute
 
@@ -334,6 +337,7 @@ module API
 
         mr_params = declared_params(include_missing: false)
         mr_params[:force_remove_source_branch] = mr_params.delete(:remove_source_branch) if mr_params[:remove_source_branch].present?
+        mr_params = convert_parameters_from_legacy_format(mr_params)
 
         merge_request = ::MergeRequests::UpdateService.new(user_project, current_user, mr_params).execute(merge_request)
 
diff --git a/lib/banzai/reference_parser/merge_request_parser.rb b/lib/banzai/reference_parser/merge_request_parser.rb
index e8147ac591a..d7bf450465e 100644
--- a/lib/banzai/reference_parser/merge_request_parser.rb
+++ b/lib/banzai/reference_parser/merge_request_parser.rb
@@ -10,7 +10,7 @@ module Banzai
           nodes,
           MergeRequest.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/gitlab/hook_data/issuable_builder.rb b/lib/gitlab/hook_data/issuable_builder.rb
index 0803df65632..b8da6731081 100644
--- a/lib/gitlab/hook_data/issuable_builder.rb
+++ b/lib/gitlab/hook_data/issuable_builder.rb
@@ -20,11 +20,7 @@ module Gitlab
           repository: issuable.project.hook_attrs.slice(:name, :url, :description, :homepage)
         }
 
-        if issuable.is_a?(Issue)
-          hook_data[:assignees] = issuable.assignees.map(&:hook_attrs) if issuable.assignees.any?
-        else
-          hook_data[:assignee] = issuable.assignee.hook_attrs if issuable.assignee
-        end
+        hook_data[:assignees] = issuable.assignees.map(&:hook_attrs) if issuable.assignees.any?
 
         hook_data
       end
diff --git a/lib/gitlab/hook_data/merge_request_builder.rb b/lib/gitlab/hook_data/merge_request_builder.rb
index d77b1d04644..a8e993e087e 100644
--- a/lib/gitlab/hook_data/merge_request_builder.rb
+++ b/lib/gitlab/hook_data/merge_request_builder.rb
@@ -34,7 +34,6 @@ module Gitlab
       end
 
       SAFE_HOOK_RELATIONS = %i[
-        assignee
         labels
         total_time_spent
       ].freeze
@@ -51,7 +50,9 @@ module Gitlab
           work_in_progress: merge_request.work_in_progress?,
           total_time_spent: merge_request.total_time_spent,
           human_total_time_spent: merge_request.human_total_time_spent,
-          human_time_estimate: merge_request.human_time_estimate
+          human_time_estimate: merge_request.human_time_estimate,
+          assignee_ids: merge_request.assignee_ids,
+          assignee_id: merge_request.assignee_ids.first # This key is deprecated
         }
 
         merge_request.attributes.with_indifferent_access.slice(*self.class.safe_hook_attributes)