Slug Validation for Contact Form 7

contact-form-7-slug-validation.php

<?php

function cf7_slug_validation($result,$tag) {
	$type = $tag['type'];
	$name = $tag['name'];


	if($type == 'text*' && $_POST[$name] == ''){
			$result['valid'] = false;
			$result['reason'][$name] = wpcf7_get_message( 'invalid_required' );
	}
//__________________________________________________________________________________________________


	// Validate for a slug-like string. Letters, numbers and dashes only but no
  // leading or trailing dashes
	$Slugs = array('sluglike', 'sluglike1', 'sluglike2');
	foreach($Slugs as $Slug){
		if($name == $Slug) {
			$slug = $_POST[$Slug];

			if($slug != '') {
        if (!preg_match('/^[A-Za-z0-9]+(?:-[A-Za-z0-9]+)*$/', $slug)) {
          $result['valid'] = false;
          $result['reason'][$name] = 'Please enter only letters, numbers or dashes';

        }
			}

		}
	}

	return $result;
}

//add filter for text field validation
add_filter('wpcf7_validate_text','cf7_slug_validation', 10, 2); // text field
add_filter('wpcf7_validate_text*', 'cf7_slug_validation', 10, 2); // Req. text field