Ruby On Rails - How to get the Object Method Caller

Let me explain my problem:

I have 2 models:

class User < AR::Base
 has_many :contacts
end
class Contact < AR::Base
 belongs_to :开发者_如何学Pythonuser
 belongs_to :user_contact_id, :class_name => "User", :foreign_key => "user_contact_id" # The "contact" is an ID from the table user.

 def self.is_contact?(user_contact_id)
  # CHECK IF THE RECORDS EXIST VIA DB OR CACHE OR WHATEVER #
 end
end

Having a instance of User as @user, you can check is_contact? like this:

@user.contacts.is_contact?(a_user_id)

This works perfectly, my problem is that I want to access to attributes of @user, inside the is_contact? method in Contact.

Is this possible?

Thank to all you guys.

Short answer: you don't need is_contact?, since ActiveRecord already defines a method that does approximately what you want: exist?

  @user.contacts.exist? :user_contact_id => a_user_id

Does Contact have it's own attributes besides id,user_id and user_contact_id? If not, you might be better off using a has and belongs to many association.

I feel like using something like @user.has_contact? other_user makes more sense than @user.contacts.is_contact? other_user

You could even roughly keep your current classes by using the :through option.

class User < AR::Base
 has_many :user_contacts
 has_many :contacts, :through => :user_contacts,:source => :user_contact_id
 def has_contact? user_id
   contacts.exists? user_id
 end
end

class UserContact < AR::Base
 belongs_to :user
 belongs_to :user_contact_id,
  :class_name => "User",
  :foreign_key => "user_contact_id" # The "contact" is an ID from the table user.

end
#
#...
@user.has_contact? other_user.id

Though using has_and_belongs_to_many would be cleaner, in that you wouldn't even need a model for your join table, just create one in a migration. Then you could

class User < AR::Base
 has_and_belongs_to_many :contacts, :class_name => "User",:source => :user_contact_id
 def has_contact? user_id
   contacts.exists? user_id
 end
end

#
#...
@user.has_contact? other_user_id

If you want to access @user attributes, then you should have something like this:

class User < AR::Base
  has_many :contacts
end

class Contact < AR::Base
  belongs_to :user
  belongs_to :user_contact_id, :class_name => "User", :foreign_key => "user_contact_id" # The "contact" is an ID from the table user.

  def is_contact?(user_contact_id)
    user.firstname = 'John' # just an example
    # CHECK IF THE RECORDS EXIST VIA DB OR CACHE OR WHATEVER #
  end
end

EDIT:

Yep,right, you also need to change how you call this method. So maybe better solution is to use named_scope:

# Contact model
named_scope :has_contact, lamda {|user_contact| { :conditions => {:user_contact_id => user_contact } } }

Then you can do:

@user.contacts.has_contact(some_id).count

It will check how many contacts with some_id has user @user.