Form Validation: Let the comma as separator to be valid in integer field input I'd like to let my users use separator (Comma) while entering values in an integer field such as price for instance.

I know that we can alter the validation of fields with element_validate_integer API, but seems like that I can't get it working.

I appreciate any helps, thanks. 

Also note that I'm using Clientside Validation module as well.
If you have integer (or Big int) field you can't submit data with , in integer field and this means that you should strip all , before data passed to Drupal default form submit handler ( as you know before data passed to submit it must be  validated first ) So  the tiny and quick solution is  you set a custom  validate handler  that  called before Drupal node validation handler then in there try to strip all , ( manipulate data in your custom validation handler ) and then enjoy it.

 // in your custom module 

function yourmodule_form_alter(&amp;$form, &amp;$form_state, $form_id)
{
    if ($form_id == 'your_form_id' ) {
                array_unshift($form['#validate'], '_mycustom_validate_handler');
}
}

function _mycustom_validate_handler($form, &amp;$form_state)
{
$form_state['values']['your_integer_field']['und'][0]['value'] =strtr($form_state['values']['your_integer_field']['und'][0]['value'] , ',' ,'');
}


And if you also  want save , in database(!!!) try text field instead using integer field  and then with client side validation  Regex  Rule validate what you want.