rails加入多态关联

Question

我在名为Notifiable的模型中命名了一个ploymorphic关联Notifiaction:

module Notifiable
  def self.included(base)
    base.instance_eval do
      has_many :notifications, :as => :notifiable, :inverse_of => :notifiable, :dependent => :destroy
    end
  end
end

class Bill < ActiveRecord::Base
  include Notifiable
end

class Balance < ActiveRecord::Base
  include Notifiable
end

class Notification
  belongs_to :notifiable, :polymorphic => true
  belongs_to :bill, foreign_key: 'notifiable_id', conditions: "notifiable_type = 'Bill'"
  belongs_to :balance, foreign_key: 'notifiable_id', conditions: "notifiable_type = 'Balance'"
end

当我尝试加入通知时通知(Notification.joins{notifiable}- 它是吱吱声,活动记录代码会有相同的结果)我得到错误:ActiveRecord::EagerLoadPolymorphicError: Can not eagerly load the polymorphic association :notifiable

我已经看过一些有关此异常的帖子,但当我尝试加入表格时,它们都不是我的情况.可能吗？我错过了什么

Answer 1

您可以使用 include 预先加载这两个多态关联：

Notification.where(whatever: "condition").includes(:notifiable)

考虑到账单和余额结果都与查询结果匹配，包含应在查询结果中预加载这两个模型。IE：

Notification.where(whatever: "condition").includes(:notifiable).map(&:notifiable)
# => [Bill, Balance, etc]