多个输入的一个验证功能

I'm using CodeIgniter's form validation callback function, here is it:

function _validate_rate($input, $field)
{

    if ( !in_array($field, array("water", "earth", "fire")) )
    {
        return FALSE;
    }

    $min = (int) $this->input->post($field . '_max');
    if ( $min > 0 AND $min < $input )
    {
        $this->form_validation->set_message($field . '_min', sprintf($this->lang->line('dev_s_invalid_rate'), strtolower($field)));
        return FALSE;
    }
    return TRUE;
}

.. I'm using the above function for three form inputs:

$form_rules = array(
    'water_min' => array (
        'field' => substr($this->lang->line('dev_field_water'), 0, -1), 
        'rules' => 'trim|xss_clean|max_length[4]|numeric|callback__validate_rate[water]'
    ),
    'earth_min' => array (
        'field' => substr($this->lang->line('dev_field_earth'), 0, -1), 
        'rules' => 'trim|xss_clean|max_length[4]|numeric|callback__validate_rate[earth]'
    ),
    'fire_min' => array (
        'field' => substr($this->lang->line('dev_field_fire'), 0, -1), 
        'rules' => 'trim|xss_clean|max_length[4]|numeric|callback__validate_rate[fire]'
    )
);
foreach( $form_rules as $input => $data) 
{
    $this->form_validation->set_rules($input, $data['field'], $data['rules']);
}

The problem appears, when I want to display a form validation error message with the following statement:

$this->form_validation->set_message($field . '_min', sprintf($this->lang->line('dev_s_invalid_rate'), strtolower($field)));

(in the callback function).

So: it should set a error message corresponding to the $field data, so when the $field is water, it should set a error message for water_min (as that is the validation rule field name).. but then I'm receiving following message:

Unable to access an error message corresponding to your field name..

I've created one callback function for three fields, just to prevent repeating same looking functions, which will have to check/work the same... unfortunately the errors corresponding to the each input can not be accessed.

change

$this->form_validation->set_message($field . '_min', sprintf($this->lang->line('dev_s_invalid_rate'), strtolower($field)));

to

$this->form_validation->set_message(_validate_rate, sprintf($this->lang->line('dev_s_invalid_rate'), strtolower($field)));

The error message corresponds to the function, not the field. That way your function can be generically used for multiple fields. In your error message you could write:

'The %s field is not correct'

and it will insert the field name into the %s