Posts will not display on page-mypage.php

Question

Something is really tripping me up. I have been used to querying posts via custom queries however based on research lately I have learned that for the most part this is a big no no. So, in testing the standard wp loop, I realized it does not work on for example, page-mypage.php. Can anyone share insight on this?

If I do something like get_title, it just gives the title for that page. I realize there is other posts about this topic on stack but all the up-voted responses are to use a custom query which again, as I have understood, is a poor method and pre_get_posts should be used instead. However, I tried using pre_get_posts function and that did not work either.

add_action( 'pre_get_posts', 'display_posts' );
function display_posts( $query ) {
if ( ! is_admin() && $query->is_main_query()) {
} // end if;
} 

Does the standard loop only work on index.php? So I am assuming the global query does not run before page.php is called? Im totally confused here as well because how would wp know to display posts on, for example, page-mypage.php unless you are querying them directly in the template?

Again, I am using the standard loop, and it is not displaying any post data.

<?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
<?php the_content(); ?>
<?php endwhile; endif; ?>

Answer 1

You can use custom query to show post in your template

$args = array(
    'post_type' => 'product',
    'posts_per_page' => 10
  );
  $loop = new WP_Query( $args );
  while ( $loop->have_posts() ) : $loop->the_post();
    the_title();
    the_content();
  endwhile;