如何将此查询转换为ActiveRecord（Rails 5）

Posted 2021-03-27

我有一个SQL查询，如下所示：

SELECT user_id, group_id
    FROM boats
    WHERE is_docked = 1
    AND (
      dock_id IS NULL
      OR
      dock_2_id IS NULL
    )

我在ActiveRecord中最接近的是：

Boat.where(is_docked: 1).where(dock_id: nil).or(Boat.where(dock_id_2:nil))

从上面生成的SQL语法不是我所期望的。什么是正确的方法呢？

答案

Boat.where('is_docked = ? AND (dock_id IS NULL OR dock_2_id IS NULL)', 1,).select(:property_id, :player_id)

要么

Update Boat Model

class Boat < ApplicationRecord
  scope :docked, -> { where('is_docked = ?', 1 }
  scope :with_unassigned_dock, -> { where('dock_id IS NULL OR dock_2_id IS NULL') }
end

new query

Boat.docked.with_unassigned_dock.select(:property_id, :player_id)