与主动型串行器贪婪加载协会 [英] Eager load associations with Active Model Serializers

问题描述

我有一个深度嵌套协会的Rails应用程序。

I have a rails application with deeply nested associations.

                          .-< WorkPeriod
Timecard -< Week -< Day -<--< Subtotal
                          `-< Adjustment

-<  (has many)

我使用活动模型串行打造出来的API。

在客户端我想加载考勤卡和它所有的协会在一杆。

On the client side I want to load a timecard and all it's associations in one shot.

目前我的串行器看起来像这样，

Currently my serializers look like this,

class TimecardSerializer < ActiveModel::Serializer
  embed :ids, include: true
  has_many :weeks
end
class WeekSerializer < ActiveModel::Serializer
  embed :ids, include: true
  has_many :days
end
# ... etc ...

问题

这所有的作品找到，但没有得到渴望加载。因此，最终使很多调用数据库为每个请求。对于每个星期，它使得在一个星期的日子里单独的请求。而对于每一天，它使得它的work_periods，小计和调整独立的要求。

Problem

This all works find, except nothing gets eager-loaded. So it ends up making lots of calls to the database for each request. For each week, it makes a separate request for the days in that week. And for each day, it makes a separate request for it's work_periods, subtotals, and adjustments.

推荐答案

一个解决方案是定义在TimecardSerializer自己的周方法。从那里你可以 .includes（）所有要急于负载关联。

One solution is to define your own weeks method on the TimecardSerializer. From there you can .includes() all the associations you want to eager load.

class TimecardSerializer < ActiveModel::Serializer
  embed :ids, include: true
  has_many :weeks

  def weeks
    object.weeks.includes(days: [:sub_totals, :work_periods, :adjustments])
  end
end

所有查询仍然会显示在日志中，但大多数将是一个缓存的查询，而不是一个真实的。

All the queries will still show up in the log but most will be a cached query instead of a real one.

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