的has_many与和named_scope [英] has_many and sum named_scope

问题描述

我有这种情况：

Stories has many Tasks
Tasks have an integer called hours_left

我需要一个命名范围，找到左故事，它的所有任务已超过0小时

根据这个帖子。我写这样的：

class Story
  has_many :tasks
  named_scope :uncompleted, { 
    :joins=>["INNER JOIN tasks ON tasks.story_id = stories.id"],
    :group=> 'stories.id',
    :select=>'stories.*, SUM(tasks.hours_left) AS sum_amount',
    :having=>"sum_amount > 0"
  }
end

但 Story.uncompleted 返回一个空数组。

您能帮我吗？

推荐答案

解决。这code的实际工作，问题是，它返回零，如果任何任务具有hours_left =零和的结果。我验证hours_left的presence而这一切。

Solved. That code actually works, the problem is that it returns nil as result of the sum if any of the tasks has hours_left = nil. I validated presence of hours_left and that's all.

这篇关于的has_many与和named_scope的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！