Question

I need to build app with user messages (dialogs).
I’ve solved this problem by this way:

app/models/conversation.rb

class Conversation < ActiveRecord::Base
  belongs_to :user
  belongs_to :interlocutor
  has_many :messages
end

app/models/message.rb

class Message < ActiveRecord::Base
  belongs_to :conversation
  belongs_to :user
  attr_accessible :message
end

app/models/user.rb

class User < ActiveRecord::Base
  ...
  def conversations
    Conversation.uniq.joins(:messages)
      .where("conversations.user_id = ?", self.id)
      .where("conversations.interlocutor_id = ?", self.id)
      .order("messages.created_at DESC")
  end
end

I’m confused by conversations method. It’s like PHP way – no flexibility.

Can it be rewrited by rails way? Maybe it can be AR relationship?

Thanks.

Answer 1

Consider scoping the query.

In Rails 3, this would look something like

class Conversation < ActiveRecord::Base
  scope :involving, lambda do |user|
    joins(:messages)
      .where("conversations.user_id = ?", user.id)
      .where("conversations.interlocutor_id = ?", user.id)
      .order("messages.created_at DESC")
  end
end

Use it like this:

Conversation.involving(me).all