Sorting forum topics by the most recent replies

I have built a simple forum but am having difficult getting the topics
to display in the order of their latest reply.

The associations are as follows:

class Forum < ActiveRecord::Base
  has_many :topics, :order => "sticky DESC, created_at DESC"
  has_many :replies, :through => :topics

class Topic < ActiveRecord::Base
  belongs_to :forum
  has_many :replies, :order => "created_at", :dependent => :destroy

class Reply < ActiveRecord::Base
   belongs_to :topic

And in my controller I am calling @topics = @forum.topics

What I would like to do is sort the topics by the created_at of their
most recent posts.

Any advice appreciated.

Thanks,

Dan

I have built a simple forum but am having difficult getting the topics
to display in the order of their latest reply.

The associations are as follows:

class Forum< ActiveRecord::Base
   has_many :topics, :order => "sticky DESC, created_at DESC"
   has_many :replies, :through => :topics

class Topic< ActiveRecord::Base
   belongs_to :forum
   has_many :replies, :order => "created_at", :dependent => :destroy

class Reply< ActiveRecord::Base
    belongs_to :topic

And in my controller I am calling @topics = @forum.topics

What I would like to do is sort the topics by the created_at of their
most recent posts.

Any advice appreciated.
   

Add a last_reply_at field to Topic. Add a after_save to Reply that updates last_reply_at. When you find all topics sort by last_reply_at.