[英]rails joins polymorphic association
我在名為Notifiaction
的模型中有一個名為Notifiable
的ploymorphic關聯:
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
當我嘗試加入通知時通知( Notification.joins{notifiable}
notifiable Notification.joins{notifiable}
- 它的吱吱聲,活動記錄代碼會有相同的結果)我得到錯誤: ActiveRecord::EagerLoadPolymorphicError: Can not eagerly load the polymorphic association :notifiable
我已經看過一些有關此異常的帖子,但當我嘗試加入表格時,它們都不是我的情況。 可能嗎? 我錯過了什么
您可以通過使用includes來急切加載兩個多態關聯:
Notification.where(whatever: "condition").includes(:notifiable)
考慮Bill和Balance結果與查詢結果匹配,include應該在查詢結果中預加載兩個模型。 即:
Notification.where(whatever: "condition").includes(:notifiable).map(&:notifiable)
# => [Bill, Balance, etc]
由於您已經聲明了帳單和余額關聯,因此您可以加入單個關聯並對其進行聯盟。
就像是
scope :billiables_for_account, ->(account) do
union_scope(joins(:bill).where(bills: {account: account}),
joins(:balance).where(bills: {account: account}))
end
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.