Question

I'm trying to write a named scope in my model that retrieves all instances that are associated with another model. This is the model where I need the scope to retrieve all instances with EmailTemplate

class Answer < ApplicationRecord
  has_one :email_template, as: :templateable
  validates :text, presence: true

  scope :with_template, -> { where.not(email_template: nil) }
end

And my other model

class EmailTemplate < ApplicationRecord
  belongs_to :templateable, polymorphic: true
  validates :pre, presence: true
  validates :post, presence: true
end

When I do Answer.with_template, this error shows up.

[3] pry(main)> Answer.with_template
   (6.6ms)  SELECT COUNT(*) FROM "answers" WHERE ("answers"."templateable" IS NOT NULL)
ActiveRecord::StatementInvalid: PG::UndefinedColumn: ERROR:  no existe la columna answers.templateable
LINE 1: SELECT COUNT(*) FROM "answers" WHERE ("answers"."templateabl...
                                              ^
: SELECT COUNT(*) FROM "answers" WHERE ("answers"."templateable" IS NOT NULL)
from /home/pedro/.rvm/gems/ruby-2.4.0/gems/activerecord-5.1.1/lib/active_record/connection_adapters/postgresql_adapter.rb:620:in `async_exec'

Tried with this too, and doesn't work:

scope :with_template, -> { where.not(templateable: nil) }

Answer 1

ActiveRecord :: StatementInvalid：PG :: UndefinedColumn：ERROR：no existe la columna answers.templateable

根据多态关联，EmailTemplate应该是templateable_id而不是Answer。所以你应该加入模型并查询它们

这应该有效

scope :with_template, -> { includes(:email_template).where.not("email_templates.templateable_id IS NULL") }

Answer 2

我刚刚找到了解决方案。注意到dataType: "json"使用自己的属性。

where

Rails 5 named scope with polymorphic, UndefinedColumn

2 个答案: