调整

app/models/subject.rb

@@ -19,7 +19,7 @@ class Subject < ApplicationRecord
   has_many :stages, -> { order("stages.position ASC") }, dependent: :destroy
 
   # 开放课堂
-  has_many :courses, -> { order("courses.id ASC") }
+  has_many :courses, -> { where("is_delete = 0").order("courses.id ASC") }
 
   validates :name, length: { maximum: 60 }
   validates :description, length: { maximum: 5000 }