XF 2.1 XenForo way to validate a simple custom <xf:form> ? (regex)

[Earl]

I have a simple form like this in a default notification block

{{ phrase('your_account_is_currently_awaiting_confirmation_confirmation_message_sent_to_x', {'phone': $xf.visitor.phone}) }}<br />
<xf:form action="{{ link('canonical:account-confirmation/phone') }}" ajax="true" class="block">
    <xf:textboxrow name="phone" type=""
                   label="{{ phrase('phone_number') }}" required="required" hint="{{ phrase('required') }}" />
    <xf:textboxrow name="c"
                   label="{{ phrase('verification_code') }}" required="required" hint="{{ phrase('required') }}" />

    <xf:submitrow submit="{{ phrase('confirm') }}" icon="login" />
</xf:form>
<a href="{{ link('account-confirmation/resendPhone') }}" data-xf-click="overlay">{{ phrase('resend_confirmation_message') }}</a>

And I know we can use <xf:textboxrow> 's type attribute and It automatically validates the form field against search, email, url, number, but what about regex?
I'm trying to verify the phone numbers that only have a specific prefix using regex. What's the XenForo way to make this work?

Note: I know I can add custom fields for phone numbers and they have convenient ways for using validations but I don't want to include the phone number in the registration form. I want to add it to the next step, so I have to use a simple form with simple regex validation.

 

[Jeremy P]

You can pass through a pattern attribute: https://www.w3schools.com/tags/att_input_pattern.asp

You should never rely solely on the client though, so you'll want to check it on the server as well. If it's for an entity column, you can do that by setting 'match' as part of the structure:

'match' => ['/^regex$/i', 'your_error_phrase']

Otherwise you'll need to check it manually.