实训作业的选用实训弹框、申请加入课堂时判断是否有同学号的用户存在

app/controllers/courses_controller.rb

@@ -883,7 +883,7 @@ class CoursesController < ApplicationController
         u_extension = current_user.user_extension
         if params[:student].present? && u_extension.student?
           same_student_id_users = UserExtension.where.not(user_id: current_user.id).where(student_id: u_extension.student_id, identity: %i[student], school_id: u_extension.school_id).pluck(:user_id)
-          tip_exception("该课堂已存在同学号的学生，暂时无法加入，请联系老师") if course.students.where(user_id: same_student_id_users).size > 0
+          tip_exception("该课堂已存在同学号的学生，暂时无法加入，请联系老师") if course.students.exists?(user_id: same_student_id_users)
         end
 
         # 创建学生身份