add short code in cms wordpress

short_code_wp_project.php

wpcf7_add_shortcode("pages","page_handler");
function page_handler(){
	$html = ' ';

	$posts = get_posts(array(
		    'showposts'=>12,
			'post_type'   => 'our-doctor',
			'order'=>'ASC',
			'order_by' => 'date'
	));
	if ($posts):
		$html =  '<select name = "pages">';
		if (isset($_GET['vrach'])){
				$vrach = $_GET['vrach'];
				$html.='<option value="'.$vrach.'" selected>'.$vrach. '</option>';

		}
		
		else if (empty($vrach) && !isset($_GET['vrach'])){
		?>
		<?php
		foreach($posts as $post){

			
				$html .= '<option value="'.$post->post_title.'">'.$post->post_title. '</option>';
			}
		}
		$html .= '</select>';
	endif;

	return $html;  
}