使用will_paginate时关联的Rails模型的顺序不正确

Question

I'm having problems ordering with the will_paginate plugin. Here are my models

Forum

class Forum < ActiveRecord::Base
    has_many :topics, :dependent => :destroy
    has_many :posts, :through => :topics

Topic

class Topic < ActiveRecord::Base
    belongs_to :forum, :counter_cache => true
    has_many :posts, :dependent => :delete_all

Post

class Post < ActiveRecord::Base
    belongs_to :topic, :counter_cache => true
    belongs_to :user

I'm trying to get the topics which have the most recent posts. The following works correctly:

forum = Forum.find(3)
forum.topics.all(:include => [:posts], :order => "posts.created_at DESC")

But when introducing pagination (using the will_paginate plugin) the ordering is incorrect.

forum = Forum.find(3)
forum.topics.paginate(:include => [:posts], :order => "posts.created_at DESC", :page => page)

Does anybody know why use of the will_paginate plugin could be detrimentally affecting ordering?

I'm using Rails 2.3.9 and will_paginate 1.6.2.

Answer 1

在Rails 3中，我认为您可以在分页调用之前将订单移至：

forum.topics.includes(:posts).order("posts.created_at DESC").paginate()

Answer 2

Do not use square brackets in :include .
Also add :per _ page parameter:

forum = Forum.find(3)
forum.topics.paginate(
        :per_page => 5,
        :page     => page,
        :include  => :posts,
        :order    => "posts.created_at DESC")