ruby-on-rails - 遍历 activerecord::relation 数组

Question

如何遍历 Activerecord::Relation 对象数组？例如，假设我有一个Comment班级和一个User班级，我想从 3 个特定用户那里获取所有评论内容（假设评论属于用户，user_id 是外键）：

>> @males = Comment.where('user_id IN (?)', ["123","456","789"])
=> [...] #Array of comment Activerecord::Relation objects

现在我想遍历comments_from_males并收集content数组中每个评论的所有属性内容。

为了澄清，以下工作但仅适用于第一个男性返回，但我需要所有男性的所有评论：

>> @males.first.comments.map(&:content)
=> ["first comment", "second comment"]

Answer 1

comments = @males.map {|user| user.comments.map(&:content)}.flatten

Answer 2

You can use

comments_from_males = @males.collect{|e| e.content if e.gender == "male"}.flatten

It will give you list of all comments from males. Check my db assumptions match.

Answer 3

Comment.where('user_id IN (?)', ["123","456","789"]).pluck(:content)

方法采摘