Resolve "Return how many commits the source branch is behind the target branch through the API"

2 files changed, 4 insertions, 1 deletions

diff --git a/lib/api/entities.rb b/lib/api/entities.rb
index 624eda3f5dd..e63f11d721e 100644
--- a/lib/api/entities.rb
+++ b/lib/api/entities.rb
@@ -687,6 +687,8 @@ module API
 
       expose :diff_refs, using: Entities::DiffRefs
 
+      expose :diverged_commits_count, as: :diverged_commits_count, if: -> (_, options) { options[:include_diverged_commits_count] }
+
       def build_available?(options)
         options[:project]&.feature_available?(:builds, options[:current_user])
       end
diff --git a/lib/api/merge_requests.rb b/lib/api/merge_requests.rb
index abad418771c..55f54fe3c43 100644
--- a/lib/api/merge_requests.rb
+++ b/lib/api/merge_requests.rb
@@ -233,6 +233,7 @@ module API
       params do
         requires :merge_request_iid, type: Integer, desc: 'The IID of a merge request'
         optional :render_html, type: Boolean, desc: 'Returns the description and title rendered HTML'
+        optional :include_diverged_commits_count, type: Boolean, desc: 'Returns the commits count behind the target branch'
       end
       desc 'Get a single merge request' do
         success Entities::MergeRequest
@@ -240,7 +241,7 @@ module API
       get ':id/merge_requests/:merge_request_iid' do
         merge_request = find_merge_request_with_access(params[:merge_request_iid])
 
-        present merge_request, with: Entities::MergeRequest, current_user: current_user, project: user_project, render_html: params[:render_html]
+        present merge_request, with: Entities::MergeRequest, current_user: current_user, project: user_project, render_html: params[:render_html], include_diverged_commits_count: params[:include_diverged_commits_count]
       end
 
       desc 'Get the participants of a merge request' do