调整

app/controllers/courses_controller.rb

@@ -1129,12 +1129,12 @@ class CoursesController < ApplicationController
 
   def validate_course_name
     tip_exception("课堂名称不能为空！") if params[:course][:name].blank?
-    if params[:subject_id].blank? || @course.subject.blank?
+    if params[:subject_id].blank? || (@course && @course.subject.blank?)
       tip_exception("课程名称不能为空！") if params[:course_list_name].blank?
       tip_exception("课堂名称应以课程名称开头命名") unless params[:course][:name].index(params[:course_list_name]) &&
         params[:course][:name].index(params[:course_list_name]) == 0
     else
-      @subject = @course ? @course.subject : Subject.find_by!(id: params[:subject_id])
+      @subject = @course.present? ? @course.subject : Subject.find_by!(id: params[:subject_id])
       tip_exception("开始时间不能为空") if params[:start_date].blank?
       tip_exception("结束时间不能为空") if params[:end_date].blank?
       tip_exception("结束时间必须晚于开始时间") if params[:end_date] <= params[:start_date]

app/models/course.rb

@@ -5,7 +5,7 @@ class Course < ApplicationRecord
 
   belongs_to :teacher, class_name: 'User', foreign_key: :tea_id  # 定义一个方法teacher，该方法通过tea_id来调用User表
   belongs_to :school, class_name: 'School', foreign_key: :school_id #定义一个方法school，该方法通过school_id来调用School表
-  belongs_to :course_list
+  belongs_to :course_list, optional: true
 
   # 所属实践课程
   belongs_to :subject, optional: true