has_many 和 sumnamed_scope
我遇到这种情况：
Stories has many Tasks
Tasks have an integer called hours_left
我需要一个命名范围来查找其所有任务剩余时间超过 0 小时的故事。
基于这篇文章。我这样写：
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
但是 Story.uncompleted 返回一个空数组。
你能帮助我吗？
I have this situation:
Stories has many Tasks
Tasks have an integer called hours_left
I need a named scope to find Stories which all its tasks has more than 0 hours left.
Based on this post. I wrote this:
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
But Story.uncompleted returns an empty array.
Can you help me?
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解决了。该代码实际上有效，问题是如果任何任务的 hours_left = nil，它会返回 nil 作为总和结果。我验证了 hours_left 的存在，仅此而已。
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.