我想基于多态关联的属性来编写作用域。
我有模特:
class Item < ApplicationRecord
belongs_to :person, polymorphic: true
end
class Teacher < ApplicationRecord
has_many :items, as: :person
end
class Student < ApplicationRecord
has_many :items, as: :person
end
老师和学生都具有属性名称,我想将该属性用于以下范围:
scope :by_name, ->(name) { joins(:person).where(persons: {name: name}) }
由于我不能只提及范围,有没有办法很好地限制范围?
答案 0 :(得分:1)
我不知道这样做的一种真正干净的方法……虽然笨重,但应该可以工作,但是扩展性不好。希望有人能有更好的答案。
scope :by_name, ->(name) { joins("left join teachers on person_type = 'Teacher' and person_id = teachers.id")
.joins("left join students on person_type = 'Student' and person_id = students.id")
.where('teachers.name = ? OR students.name = ?', name, name) }
要处理名称数组,可以如下进行修改...
scope :by_name, ->(*name) do
name = name.flatten
joins("left join teachers on person_type = 'Teacher' and person_id = teachers.id")
.joins("left join students on person_type = 'Student' and person_id = students.id")
.where('teachers.name IN (?) OR students.name IN (?)', name, name)
end
这将使您可以做到
item.by_name('Smith')
item.by_name('Smith', 'Jones')
item.by_name(['Smith', 'Jones'])