Such validations are not native to Forms, and if you need or want to see them in Forms, or Toolset, you would have to suggest them here https://toolset.com/home/contact-us/suggest-a-new-feature-for-toolset/
Product Management can then decide to implement such features or not.
To understand what you can validate with the Toolset Forms API hook cred_form_validate() you need minimal PHP and WordPress API understanding.
Then, you can consult this DOC https://toolset.com/documentation/programmer-reference/cred-api/#cred_form_validate where we explain how the hook works.
To find out what you can validate you should always use something like error_log(print_r($variable_to_debug, true));, with this statement you can see exactly what is in the $variable_to_debug.
In our case this would be $fields, to see if the Post title is part of this variable.
It is, as if you do error_log(print_r($data, true)) in your form you will see that it is an array of arrays.
And one of the first keys is "post_title"
That is the value of the post title field.
It is by default validated with
[active] => 1
[value] => 1
[message] => This field is required
So, you can check this for example (if title has more than 20 characters)
add_filter( 'cred_form_validate', 'my_function', 10, 2 );
function my_function( $data, $form_data ) {
list($fields,$errors)=$data;
// error_log(print_r($fields, true));
// error_log(print_r($errors, true));
if ( strlen($fields['post_title']['value']) > 20 ) {
$errors['post_title'] = __('Maximum 20 characters for this field', 'your-language-domain');
}
$data =array($fields,$errors);
return $data;
}
Note that this is custom code, and for complete custom code assistance, you'd have to contact a contractor or other 3rd party developers (https://toolset.com/contractors/).
I hope the above helps!
