Add NOT to the Validation rules or callbacks

[sasan]

Add ! to the validation rules or at least callbacks. So that you can have a rule by which you will be able to have the opposite result.

[allain]

Usage might be: $validation->add_rules('username', '!username_exists', '!email');

It's a pretty specific use case, but I see value in it.

Though this is unnecessary, developers can always code their own callbacks that checks for the opposite of a builtin, it'd make the intent clearer with less developer code.

[sasan]

In this case I meant to use same callbacks in different cases. For example 'username_exist' and '!username_exist'

[allain]

Of course. All I was agreeing with you. Instead of having two callbacks, you could use one.

I like it.

[spirit]

I'm not sure that this feature is necessary. It will bring some problem for example in forms validation error messages: only one method so only one message for two different tests.

Moreover:

function username_exists() {
 // Code here
}
function username_not_exists() {
 return !$this->username_exists();
}
$validation->add_rules('username', 'username_exists');
$validation->add_rules('username1', 'username_not_exists');

is not really heavy.

[Shadowhand]

I agree with spirit, this adds too much complexity to error reporting, and the use case is rather small, imo.