Mandatory fields and username restrictions on a WordPress site.


I have a WordPress site but I have no experience with PHP. The website has an account sign up page.

I'd like to make filling out the 'First Name' and the 'Last Name' fields a requirement when users sign up for an account. I'd also like to implement 'Username' creation restrictions, for example:

The following special characters are not allowed:
" / \ [ ] : ; | = , + * ? < >

For the required fields, I can probably copy the code from the other required fields that is already in place. But the restriction I don't know how to do. Does anybody have a sample code that I can take a look at?

Thank you  in advance!
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Ray PaseurCommented:
In case you're interested in learning PHP (kind of a requirement if you're going to make changes to WordPress functionality) this article may be able to help you find the way forward.
Mark BradyPrincipal Data EngineerCommented:
I would do a restriction check on the front end first using javascript but here is a way you could look for those characters on the back end (PHP).

$invalid_characters = array('"', '/', '\', '[', ']', ':', ';', '|', '=', '+', '*', '?', '<', '>');
$valid = false;
for ($i = 0; $i < strlen($username); $i++) {
	if (in_array($username[$i], $invalid_characters)) {		
	$valid = true;

if (!$valid) {
	// do something here. Return an error

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petaganayrAuthor Commented:
Thank you for the input. I'll be doing some testing this weekend. I will let everyone know how it went.
petaganayrAuthor Commented:
Thank you for the comments. I chose Mark's comment because I used his example and made my own lines of codes.
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