First checkin

app/models/comment.rb

@@ -0,0 +1,48 @@
+class Comment < ActiveRecord::Base
+  acts_as_nested_set :scope => [:commentable_id, :commentable_type]
+  attr_accessible :commentable, :body, :user_id
+  validates_presence_of :body
+  validates_presence_of :user
+
+  # NOTE: install the acts_as_votable plugin if you
+  # want user to vote on the quality of comments.
+  #acts_as_votable
+
+  belongs_to :commentable, :polymorphic => true
+
+  # NOTE: Comments belong to a user
+  belongs_to :user
+
+  # Helper class method that allows you to build a comment
+  # by passing a commentable object, a user_id, and comment text
+  # example in readme
+  def self.build_from(obj, user_id, comment)
+    new \
+      :commentable => obj,
+      :body        => comment,
+      :user_id     => user_id
+  end
+
+  #helper method to check if a comment has children
+  def has_children?
+    self.children.any?
+  end
+
+  # Helper class method to lookup all comments assigned
+  # to all commentable types for a given user.
+  scope :find_comments_by_user, lambda { |user|
+    where(:user_id => user.id).order('created_at DESC')
+  }
+
+  # Helper class method to look up all comments for
+  # commentable class name and commentable id.
+  scope :find_comments_for_commentable, lambda { |commentable_str, commentable_id|
+    where(:commentable_type => commentable_str.to_s, :commentable_id => commentable_id).order('created_at DESC')
+  }
+
+  # Helper class method to look up a commentable object
+  # given the commentable class name and id
+  def self.find_commentable(commentable_str, commentable_id)
+    commentable_str.constantize.find(commentable_id)
+  end
+end