Rails includes nested relations

问题

I need to query all posts from a specific user and include all comments and the user who belongs to the comment.

class User < ...
  has_many :posts
  has_many :comments
end

class Post < ...
  belongs_to :user
  has_many :comments
end

class Comment < ...
  belongs_to :user
  belongs_to :post
end

@posts = current_user.posts.include(:comments)

Is is possible to also get the comment user? I list a lot of posts and comments. I do not want to query each comment user.

Thx / Tobias

回答1:

Try

@posts = current_user.posts.includes( :comments => :user)

Read more about it here

回答2:

How about include at the relation definition statement?

:include
Specify second-order associations that should be eager loaded when this object is loaded.

class Post <
  belongs_to :user
  has_many :comments, :include => [:user], :limit => 5
end

来源：https://stackoverflow.com/questions/8554498/rails-includes-nested-relations