diff --git a/app/api/mobile/entities/course.rb b/app/api/mobile/entities/course.rb
index 8e5609f32..0dd0d6aeb 100644
--- a/app/api/mobile/entities/course.rb
+++ b/app/api/mobile/entities/course.rb
@@ -3,14 +3,17 @@ module Mobile
     class Course < Grape::Entity
       def self.course_expose(field)
         expose field do |f,opt|
-          o = nil
-          o = f.img_url if f.respond_to?(:img_url)
+          c = nil
           if f.is_a? ::Course
-            o = f.send(field) if f.respond_to?(field)
+            c = f
           else
-            f[:course][field] || f[:course].__send__(field)
+            c = f[:course]
+          end
+          if field == :img_url
+            f.img_url if f.respond_to?(:img_url)
+          else
+            (c[field] if (c.is_a?(Hash) && c.key?(field))) || (c.send(field) if c.respond_to?(field))
           end
-          o
         end
       end
       course_expose :img_url
@@ -39,7 +42,13 @@ module Mobile
       course_expose :term
       course_expose :time
       course_expose :updated_at
-      course_expose :teacher
+      expose :teacher, using: Mobile::Entities::User do |c, opt|
+        if c.is_a? ::Course
+          c.teacher
+        else
+          c[:course].teacher
+        end
+      end
     end
   end
 end