gem paranoia - PG::SyntaxError：错误：“FROM”处或附近的语法错误答案

【问题标题】：gem paranoia - PG::SyntaxError: ERROR: syntax error at or near "FROM"gem paranoia - PG::SyntaxError：错误：“FROM”处或附近的语法错误
【发布时间】：2019-01-20 02:18:22
【问题描述】：

在我的应用程序中，我有以下模型

费用.rb

class Fee < ActiveRecord::Base
  acts_as_paranoid
  belongs_to :instructor_student
  belongs_to :instructor
  has_many :fee_payment_notifications, dependent: :destroy
end

fee_payment_notifications.rb

class FeePaymentNotification < ActiveRecord::Base
  belongs_to :fee
end

instructor.rb

class Instructor < ActiveRecord::Base
  has_many :fees
  has_many :fee_payment_notifications, through: :fees
end

我想通过费用支付通知来做内部加入费用当我直接将费用加入与费用支付通知一起使用时，它会给我以下错误

@instructor.fee_payment_notifications.joins(:fee)

PG::UndefinedTable: ERROR:  invalid reference to FROM-clause entry for table "fees"
LINE 1: ..."."id" = "fee_payment_notifications"."fee_id" AND "fees"."de...
                                                             ^
HINT:  Perhaps you meant to reference the table alias "fees_fee_payment_notifications".
: SELECT "fee_payment_notifications".* FROM "fee_payment_notifications" INNER JOIN "fees" "fees_fee_payment_notifications" ON "fees_fee_payment_notifications"."id" = "fee_payment_notifications"."fee_id" AND "fees"."deleted_at" IS NULL INNER JOIN "fees" ON "fee_payment_notifications"."fee_id" = "fees"."id" WHERE "fees"."deleted_at" IS NULL AND "fees"."instructor_id" = $1

可能是因为 deleted_at 字段，这就是为什么我想使用以下查询进行手动连接

@instructor.fee_payment_notifications.select("fee_payment_notifications.* from fee_payment_notifications AS fp INNER JOIN fees as f ON fp.fee_id = f.id")

它给了我以下错误

PG::SyntaxError: ERROR: "FROM" 处或附近的语法错误第 1 行： ...ns AS fp INNER JOIN 费用为 f ON fp.fee_id = f.id FROM "fee_... ^ : SELECT fee_payment_notifications.* from fee_payment_notifications AS fp INNER JOIN fee as f ON fp.fee_id = f.id FROM "fee_payment_notifications" INNER JOIN "fees" ON "fee_payment_notifications"."fee_id" = "fees"."id" WHERE "fees "."deleted_at" 为空且 "fees"."instructor_id" = $1 => #

我应该如何编写手动加入费用和费用支付通知的查询？

【问题讨论】：

写成@instructor.fee_payment_notifications.joins(:fees).select("fee_payment_notifications.*")。你写的是产生无效的 SQL。 Rails .select() 没有被那样使用。
@ArupRakshit 它应该是 join(fee) 也不起作用
Rails 有一个方法调用 .joins() 而不是 .join().. 新错误是什么？你有has_many :fees，所以它应该是joins(:fees)。
@ArupRakshit 是的，我的意思是 joins(:fee) 。我想通过付费通知加入费用，而不是让教师检查我更新的问题。

标签： ruby-on-rails postgresql

【解决方案1】：

这不是查询问题。这是因为paranoia gem。所以你应该在你的模型中写这个。

acts_as_paranoid without_default_scope: true

请查看this 链接。你可以找到添加默认范围。

【讨论】：