Getting all categories even with no products under it?

Question

I am trying to get all categories which are having products but getting also the categories which are having no products.

WordPress version 4.6.1

wp_dropdown_categories( 
   array( 
          'class' => 'product-category-field',
          'id' => 'product-category',
          'name' => 'category',
          'taxonomy' => 'product_cat',
          'selected' => get_query_var('product_cat' ), 
          'hierarchical' => 1, 
          'hide_empty' => 1, 
          'value_field' => 'slug', 
          'show_count' => 1 
      )
);

Even get_terms is displaying empty categories with the below code.

<?php  $terms = get_terms('product_cat', array( 'parent' => 0 ));
     if( $terms ): 
     $original_query = $wp_query;
     foreach ( $terms as $key => $term ):
        ?>
        <li>
          <?php echo $term->name; ?>
          <ul>
          <?php
          $child_terms = get_terms(
              'product_cat',
               array(
                   'child_of' => $term->term_id,
                   'hide_empty' => true
               )
          );
          foreach ( $child_terms as $child_term  ) {
             $re_child_terms = get_terms(
                 'product_cat',
                 array(
                     'child_of' => $child_term->term_id,
                     'hide_empty' => true
                 )
             );
             if ( ! $re_child_terms ){
             ?>
         <li>
            <?php echo $child_term->name; ?>
        </li>
        <?php
        }
     }
     ?>
     </ul>
  </li>
<?php
endforeach;
$wp_query = null;
$wp_query = $original_query;
?>
</ul>
<?php endif; ?>

Note: In both case do not want to display categories having zero products.

Answer 1

This is very simple to list all the categories, even if they do not have any post associated with those.

You just need to set following property to false in wp_dropdown_categories. method.

'hide_empty' => 0,
'hide_if_empty' => 1

Hope this will solve your problem.

Answer 2

wc_product_dropdown_categories() will do the trick in place of wp_dropdown_categories() .

For get_terms part

by replacing

$re_child_terms = get_terms( 'product_cat', array( 'child_of' => $child_term->term_id, 'hide_empty' => true ) );
if ( ! $re_child_terms ){

with

   $re_child_terms = get_term_children( $child_term->term_id, 'product_cat' );
   if ( $child_term->count > 0 && empty( $re_child_terms ) ){

solved my problem.

Not sure but I think the problem with get_terms is here

// Make sure we show empty categories that have children.
        if ( $hierarchical && $args['hide_empty'] && is_array( $terms ) ) {
            foreach ( $terms as $k => $term ) {
                if ( ! $term->count ) {
                    $children = get_term_children( $term->term_id, $term->taxonomy );
                    if ( is_array( $children ) ) {
                        foreach ( $children as $child_id ) {
                            $child = get_term( $child_id, $term->taxonomy );
                            if ( $child->count ) {
                                continue 2;
                            }
                        }
                    }

                    // It really is empty.
                    unset( $terms[ $k ] );
                }
            }
        }