add json actions for approvals/approve/unapprove

app/controllers/projects/merge_requests_controller.rb

@@ -496,11 +496,29 @@ class Projects::MergeRequestsController < Projects::ApplicationController
       new(project, current_user).
       execute(@merge_request)
 
-    redirect_to merge_request_path(@merge_request)
+    render_approvals_json
+  end
+
+  def approvals
+    render_approvals_json
+  end
+
+  def unapprove
+    if merge_request.has_approved?(current_user)
+      MergeRequests::RemoveApprovalService.
+        new(project, current_user).
+        execute(@merge_request)
+    end
+
+    render_approvals_json
   end
 
   protected
 
+  def render_approvals_json
+    render json: API::Entities::MergeRequestApprovals.new(@merge_request)
+  end
+
   def selected_target_project
     if @project.id.to_s == params[:target_project_id] || @project.forked_project_link.nil?
       @project

config/routes/project.rb

@@ -96,7 +96,10 @@ constraints(ProjectUrlConstrainer.new) do
           post :toggle_subscription
 
           ## EE-specific
-          post :approve
+          get :approvals
+          post :approvals, to: :approve
+          delete :approvals, to: :unapprove
+
           post :rebase
           ## EE-specific