formcierge_validate_field

Filter

Since v1.0.0

Add custom validation for any field type. Return a non-empty error string to fail validation, or null/empty to pass.

Parameters

$error string|null Existing error message, or null if validation has passed so far.

$value mixed The submitted value.

$field array The field definition array.

Defined in

includes/Core/FormValidator.php

Basic Usage

add_filter( 'formcierge_validate_field', function ( $error, $value, $field ) {
    if ( $field['type'] === 'email' && $value ) {
        $domain = explode( '@', $value )[1] ?? '';
        if ( $domain && ! checkdnsrr( $domain, 'MX' ) ) {
            return 'Please enter a valid email address with a working domain.';
        }
    }
    return $error;
}, 10, 3 );

Real-World Examples

Require a minimum word count on a textarea

add_filter( 'formcierge_validate_field', function ( $error, $value, $field ) {
    if ( $field['id'] === 'field_message' && str_word_count( $value ) < 10 ) {
        return 'Please write at least 10 words.';
    }
    return $error;
}, 10, 3 );