def valid_filter(valid_filters, filter)
			if filter && filter.is_a?(Hash)
				filter.keys.each do |filter_key|
					# validates if filter criteria is recognized
					raise Exception.new("Invalid filter criteria '#{filter_key.to_s}'") if !valid_filters.key?(filter_key.to_s)
					# validates the filter criteria value
					valid_filter_value(filter_key, filter[filter_key])
				end
			end
			return true
		end
def valid_filter(valid_filters, filter)
			if filter && filter.is_a?(Hash)
				filter.keys.each do |filter_key|
					# validates if filter criteria is recognized
					raise Exception.new("Invalid filter criteria '#{filter_key.to_s}'") if !valid_filters.key?(filter_key.to_s)
					# validates the filter criteria value
					valid_filter_value(filter_key, filter[filter_key])
				end
			end
			return true
		end
Internal : Validates the filter attribute at the ReporRequest initialization
 At the first invalid filter criteria or value detected this method raises Exception.
 If all filter criteria and values are ok, this method returns true
 Valid filter criteria are validated against FILTERS_CRITERIA constant
 Valid filter values are validated against FILTERS constant

 Author:: jlopezn@neonline.cl

 === Parameters
 valid_filters - Hash with the set of valid filter values
 filter - Hash with the filter criteria and values

 Returns:: true if filter is valid

 Raises:: Exception at the first invalid filter criteria o value