mysql - 包含 Rails 3 上的外部左连接

Question

有没有办法执行 .includes 并指定一个外部左连接。

最初:

@post = Post.includes(:comments).where("comments.spam = ?", false).where(:id => params[:id]).first
@comments = post.comments

愿望是模仿:

@post = Post.find(params[:id])
@comments = post.comments.where(:spam => false)

除非使用 include 会以急切加载的方式执行它(如果说我有多个帖子)。

感谢您的帮助。贾斯汀

Answer 1

我会做以下事情:

class Post < ActiveRecord::Base
  has_many :comments

  has_many :non_spam_comments, :through => :comments, :conditions => {:spam => false} 
  has_many :spam_comments, :through => :comments, :conditions => {:spam => true}
end

然后，您将能够:

@posts = Post.where(:user_id => current_user.id).includes(:non_spam_comments)
@posts.each do |post|
  post.non_spam_comments.each do |comment| 
    // Some comment operation
  end
end