function validate_filters()
{
foreach ($this->filters as $field => $values) {
# filter requires one or more values
# filter doesn't require any value
$value = $this->values_for($field);
if (!(!is_null($value) && !empty($value[0]) || in_array($this->operator_for($field), array("o", "c", "!*", "*", "t", "w")))) {
$this->invalidate($this->label_for($field), 'Please be sure to input.');
}
}
return true;
}