How to create a shortcode for custom page template

I have a custom page template and I want it to display on specific pages. The only way I know to do this is to create a shortcode for this custom page template, so that I can use the custom page template by using shortcode. But I don’t know how doing this.

I saw some article about this, but I forgot the website link.

How to create a shortcode for custom page template?

I solved now, by adding this snippet in functions.php

function my_form_shortcode() {
   ob_start();
   get_template_part('my_form_template');
   return ob_get_clean();   
} 
add_shortcode( 'my_form_shortcode', 'my_form_shortcode' );