Dynamic Bootstrap Carousel Custom Post Type Query in Shortcode

Dynamic Bootstrap Carousel Custom Post Type Query in Shortcode

function slider_shortcode() {
	$args = array( 'post_type' => 'slider', 'posts_per_page' => 4 );
	$loop = new WP_Query( $args );
	
	$return = '<div id="carousel-example-generic" class="carousel slide carousel-fade" data-ride="carousel">
        <ol class="carousel-indicators">';
		while ( $loop->have_posts() ) : $loop->the_post();
		
		$numbers = $loop->current_post;
		$active = ( $loop->current_post == 0 ) ? 'class="active"' : '';
			
		$return .= '<li data-target="#carousel-example-generic" data-slide-to="'.$numbers.'" '.$active.'></li>';
		
		endwhile; 
		
	$return .= '</ol><div class="carousel-inner">';
	
		while ( $loop->have_posts() ) : $loop->the_post();
		
			$image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'full' );
			
			$active = ( $loop->current_post == 0 ) ? 'active' : '';
			
			$return .= '<div class="item '.$active.'">
						<img src="'.$image[0].'" alt="" />
					<div class="container">
						<div class="carousel-caption">
							'.get_the_content().'
						</div>
					</div></div>';
	
		endwhile; 
			
	$return .= '</div></div>';
	
	return $return;
		
}

add_shortcode('slider', 'slider_shortcode');

how to use this code on backend?