diff --git a/app/models/group.rb b/app/models/group.rb
index 4e8f6c12a..393069884 100644
--- a/app/models/group.rb
+++ b/app/models/group.rb
@@ -16,13 +16,12 @@ class Group < ActiveRecord::Base
   validates :uname, :presence => true, :uniqueness => {:case_sensitive => false}, :format => { :with => /^[a-z0-9_]+$/ }
   validate { errors.add(:uname, :taken) if User.where('uname LIKE ?', uname).present? }
 
-  scope :search_order, order("CHAR_LENGTH(uname) ASC")
-  scope :without, lambda {|a| where("groups.id NOT IN (?)", a)}
-  scope :search, lambda {|q| where("uname ILIKE ?", "%#{q.strip}%")}
   scope :opened, where('1=1')
   scope :by_owner, lambda {|owner| where(:owner_id => owner.id)}
   scope :by_admin, lambda {|admin| joins(:objects).where(:'relations.role' => 'admin', :'relations.object_id' => admin.id, :'relations.object_type' => 'User')}
 
+  include Modules::Models::ActsLikeMember
+
   attr_accessible :description
   attr_readonly :own_projects_count
 
diff --git a/app/models/user.rb b/app/models/user.rb
index 463264110..81545e56a 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -47,14 +47,13 @@ class User < ActiveRecord::Base
   attr_readonly :uname, :own_projects_count
   attr_accessor :login
 
-  scope :search_order, order("CHAR_LENGTH(uname) ASC")
-  scope :without, lambda {|a| where("users.id NOT IN (?)", a)}
-  scope :search, lambda {|q| where("uname ILIKE ?", "%#{q.strip}%")}
   scope :opened, where('1=1')
   scope :banned, where(:role => 'banned')
   scope :admin, where(:role => 'admin')
   scope :real, where(:role => ['', nil])
 
+  include Modules::Models::ActsLikeMember
+
   after_create lambda { self.create_notifier }
 
   def admin?
diff --git a/lib/modules/models/acts_like_member.rb b/lib/modules/models/acts_like_member.rb
new file mode 100644
index 000000000..0db4dd577
--- /dev/null
+++ b/lib/modules/models/acts_like_member.rb
@@ -0,0 +1,33 @@
+# -*- encoding : utf-8 -*-
+module Modules
+  module Models
+    module ActsLikeMember
+      extend ActiveSupport::Concern
+
+      included do |klass|
+        scope :not_member_of, lambda { |item|
+          where("
+            #{klass.table_name}.id NOT IN (
+              SELECT relations.object_id
+              FROM relations
+              WHERE (
+                relations.object_type = '#{klass.to_s}'
+                AND relations.target_type = '#{item.class.to_s}'
+                AND relations.target_id = #{item.id}
+              )
+            )
+          ")
+        }
+
+        scope :search_order, order("CHAR_LENGTH(uname) ASC")
+        scope :without, lambda {|a| where("#{klass.table_name}.id NOT IN (?)", a)}
+        scope :search, lambda {|q| where("#{klass.table_name}.uname ILIKE ?", "%#{q.strip}%")}
+
+      end
+
+      module ClassMethods
+      end
+    end
+  end
+end
+