从联接更改为包含中断查询

Question

我有这个工作查询：

@search = Availability.joins{facility.activities}
.where{activities.id == s_activity}

但我的观点是从 Facilities 获取了大量信息，这导致了 N+1 问题。

所以我决定我应该使用 includes 而不是急切加载我的关联

@search = Availability.includes{facility.activities}
.where{ facility.activities.id == s_activity)}

但这会导致错误：

!! #<ActiveRecord::StatementInvalid: PG::UndefinedTable: ERROR:  missing FROM-clause entry for table "activities"
LINE 1: ...T "availabilities".* FROM "availabilities" WHERE ("activitie...
                                                             ^

这些是协会：

class Activity < ActiveRecord::Base
  has_and_belongs_to_many :facilities
end

class Availability < ActiveRecord::Base
  # Associations
  belongs_to :facility
end

class Facility < ActiveRecord::Base
  #  Associations
  has_and_belongs_to_many :activities
  has_many :availabilities

end

has_and_belongs_to_many

有一个名为 activities_facilities 的 table

Answer 1

在条件.

中使用includes时需要附加.references

Availability.includes(facility: [:activities]).where('activities.id = ?', s_activity).references(:facility, :activities)

If you want to add conditions to your included models you’ll have to explicitly reference them

参考条件部分includes

从联接更改为包含中断查询

Changing from joins to includes breaking query

sql

postgresql

ruby-on-rails

squeel

ruby-on-rails-4