Added Base.exists?(id) that'll return true if an object of the class with the given id exists #854 [stian@grytoyr.net]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@913 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

1 files changed, 7 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 7fbef9f07c..f85cad1f98 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -326,6 +326,13 @@ module ActiveRecord #:nodoc:
         end
       end
 
+      # Returns true if the given +id+ represents the primary key of a record in the database, false otherwise.
+      # Example:
+      #   Person.exists?(5)
+      def exists?(id)
+        !find_first("#{primary_key} = #{sanitize(id)}").nil?
+      end
+
       # This method is deprecated in favor of find with the :conditions option.
       # Works like find, but the record matching +id+ must also meet the +conditions+.
       # +RecordNotFound+ is raised if no record can be found matching the +id+ or meeting the condition.