copy extra_validations plugin from branch

git-svn-id: http://www.rousette.org.uk/svn/tracks-repos/trunk@507 a4c988fc-2ded-0310-b66e-134b36920a42

tracks/vendor/plugins/extra_validations/init.rb

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+require 'extra_validations'
+ActiveRecord::Base.extend ExtraValidations

tracks/vendor/plugins/extra_validations/lib/extra_validations.rb

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+module ExtraValidations
+  
+  # Validates the value of the specified attribute by checking for a forbidden string
+  #
+  #   class Person < ActiveRecord::Base
+  #     validates_does_not_contain :first_name, :string => ','
+  #   end
+  #
+  # A string must be provided or else an exception will be raised.
+  #
+  # Configuration options:
+  # * <tt>message</tt> - A custom error message (default is: "is invalid")
+  # * <tt>string</tt> - The string to verify is not included (note: must be supplied!)
+  # * <tt>on</tt> Specifies when this validation is active (default is :save, other options :create, :update)
+  # * <tt>if</tt> - Specifies a method, proc or string to call to determine if the validation should
+  # occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }).  The
+  # method, proc or string should return or evaluate to a true or false value.
+  def validates_does_not_contain(*attr_names)
+    configuration = { :message => ActiveRecord::Errors.default_error_messages[:invalid], :on => :save, :string => nil }
+    configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)
+
+    raise(ArgumentError, "A string must be supplied as the :string option of the configuration hash") unless configuration[:string].is_a?(String)
+
+    validates_each(attr_names, configuration) do |record, attr_name, value|
+      record.errors.add(attr_name, configuration[:message]) if value.to_s =~ Regexp.new(Regexp.escape(configuration[:string]))
+    end
+  end
+  
+end