已经创建过作品的用户不允许重复创建

app/controllers/student_work_controller.rb

@@ -13,10 +13,15 @@ class StudentWorkController < ApplicationController
   end
 
   def new
+    student_work = @homework.student_works.where("user_id = ?",User.current.id).first
+    if student_work.nil?
       @stundet_work = StudentWork.new
       respond_to do |format|
         format.html
       end
+    else
+      render_403
+    end
   end
 
   def create