I'd like to to if it is  possible \"out-of-the-box\" (without big hacking), to have a mandatory field dependant of a previous selection in the form :

I explain with my case :

I have a radiobutton field \"Send your drawing\" with 2 cases : – by fax, -by mail

If the client selects by mail, he would have to submit a file (mandatory), but if he selects by fax, the file shouldn't be mandatory to be sent.

So how to achieve that ?

Thanks in advance

I've tried in the page displaying the form :

var radiofield = 'cf_field_16';

var uploadfield = 'cf_uploadfile-17';

jQuery("input").click(function(){
if (jQuery('input[type=submit]')
&& jQuery('input[type=radio][name='+radiofield+']:checked').val() == 'mail'
&& jQuery('#'+uploadfield)[0].value == ''){
var text = jQuery('#usermessageb span').text();
if (text.indexOf("upload a file") < 0){
jQuery('#usermessageb span').html(text+"<br />Please upload a file");
return false;
}
}
jQuery('form[id=cformsform]').submit(function(){
console.log('Submit blocked!');
return false;
});
});

This adds a message "Please upload a file" at the end of the warning if i don't choose a file when the file radiobutton is checked, but the form is still sent, even without the file : the ajax stuff of cforms overrides this because the file is not checked mandatory in the admin.

Can't we override or bypass the js for this part ?