def call(target)
value = target.send(field_name)
return true if @options[:allow_nil] && value.blank?
opts = {
:fields => target.model.key,
field_name => value,
}
Array(@options[:scope]).each { |subject| opts[subject] = target.send(subject) }
resource = DataMapper.repository(target.repository.name) { target.model.first(opts) }
return true if resource.nil?
return true if target.saved? && resource.key == target.key
error_message = @options[:message] || ValidationErrors.default_error_message(:taken, field_name)
add_error(target, error_message, field_name)
false
end