wp_insert_term bug doesn't update edit-tags.php right side tree

[justindgivens]

With a custom taxonomy if I use wp_insert_term() and insert a couple terms then process to the wp-admin/edit-tags.php page for that term the right side "tree" don't display the correct "tree". It might display one or two new items, but not all. Here some test code to duplicate the bug.

<?php
$category = array('Built-In Oven','Double','Electric'); //Nested Hierarchy Terms to be inserted.
// Term Hierarchy should come out like 'Built-In Oven' -> 'Double' -> 'Electric'

$catCount = 0;
$tempCatArray = array();
foreach($category as $cat) {
  if ($catCount == 0) {
    $term_id = term_exists( $cat , 'product_type' );
    if ($term_id == 0) {
      $term_id = wp_insert_term( $cat , 'product_type' ); //This term shows up but no children do.
      array_push( $tempCatArray , $term_id['term_id'] );
    } else {
      array_push( $tempCatArray , $term_id['term_id'] );
    }
  } else {
    $term_id = term_exists( $cat , 'product_type' , (int) $tempCatArray[$catCount-1] );
    if ($term_id == 0) {
      $term_id = wp_insert_term( $cat , 'product_type' , array( 'parent' => (int) $tempCatArray[$catCount-1] ) ); //New inserts aren't showing until I resaved a term.
      array_push( $tempCatArray , $term_id['term_id'] );
    } else {
      array_push( $tempCatArray , $term_id['term_id'] );
    }
  }
  $catCount++;
}

?>

Now if I go and edit a term with no changes and hit save. The tree is now updated correctly. I don't even have to edit one of the new terms, just any. I've attached two images to show this happening.

before editing a term and saving it.

After saving a term the tree is now updated.

Related: #18615

The problem you're facing is caching. wp_insert_term() will call functions to clear out the cache that stops the hierarchy displaying properly (clean_term_cache() -> _get_term_hierarchy()). So if you were to only add one term all would be okay. However, you're inserting multiple terms on a single page load...

• clean_term_cache() contains some code, in the form of a static variable, to stop a taxonomy's hierarchy being rebuilt multiple times on a single page load.
• because the code executes so fast the last_changed cache item in the terms group will not actually be changed on every term insert. Therefore, even if the above didn't occur, the result of get_terms() would be cached and only include the first term to be inserted (and any which existing prior) so _get_term_hierarchy() will return 'incorrect' information.

I'm afraid I cannot think of a nice workaround right now.

With the script above, could I not run

do_action('clean_term_cache', $tempCatArray, 'product_type');

after the foreach finishes?

@justindgivens: Calling the 'clean_term_cache' won't do much.

Going to close this as a dup of #14485 since it's essentially the same issue.