Rails - 传递给 #or 的关系必须在结构上兼容。不兼容的值：[:joins]

Question

我想在我的 rails 应用程序中合并两个查询。每一个都不是很复杂，但是我不能合并它们。

owner_packages = Package.where(owner: current_user)
admins_packages = current_user.managed_packages
@managable_packages = owner_packages.or(admins_packages)

用户.rb

has_many :package_admins, dependent: :destroy
has_many :managed_packages, through: :package_admins, source: :package

package.rb

  has_many :package_admins, dependent: :destroy
  has_many :admins, through: :package_admins, source: :user

我遇到了这个错误：

传递给#or 的关系必须在结构上兼容。不相容 值：[:joins]

Answer 1

我认为您正在寻找的是子选择：

owner_packages = Package.where(owner: current_user)
admins_packages = current_user.managed_packages
@managable_packages = owner_packages.or(Package.where(id: admins_packages))

这段代码真的应该移到模型中，而不是让所有的电线都悬空：

class User < ApplicationRecord
  has_many :owned_packages, class_name: 'Package',
                            foreign_key: :owner_id # just guessing here
  has_many :package_admins, dependent: :destroy
  has_many :managed_packages, through: :package_admins, source: :package


  def managable_packages 
    owned_packages.or(Package.where(id: managed_packages))
  end
end

另一种方法是使用联合：

class User < ApplicationRecord 
  # ...

  def managable_packages
    Package.from(
      owned_packages.arel.union(managed_packages.arel).as('packages')
    )
  end
end