使用wordpress函数get_terms的PHP错误

Question

I'm setting a variable in my site this way:

$args = array('parent' => 2818,'hide_empty' => false);
$best_of_cat_child_terms = get_terms( $args ); -> (functions.php:26)
$best_of_cat = $best_of_cat_child_terms;

The problem is that I'm also getting this php error:

Warning:

Invalid argument supplied for foreach()

Location:

wp-includes/class-wp-term-query.php:373

Call Stack:

WP_Term_Query->get_terms()
 wp-includes/class-wp-term-query.php:287
WP_Term_Query->query()
 wp-includes/taxonomy.php:1217
get_terms()
 wp-content/themes/theme-child/functions.php:26 (-> functions.php line 26 marked above)

Am I setting this the right way?

Answer 1

You can check for the error with is_wp_error() ,

$terms = get_terms( array(
      'taxonomy'=> 'category',
      'parent' => 2818,
      'hide_empty' => 0) 
);

if ( ! empty( $terms ) && ! is_wp_error( $terms ) ){
  echo '<ul>';
    foreach ( $terms as $term ) {
        echo '<li>' . $term->name . '</li>';
    }
  echo '</ul>';
}
else{
  $error_string = $terms->get_error_message();
  echo '<div id="message" class="error"><p>' . $error_string .'</p></div>';
}

About the error you told in comment, it's look like you don't run with a WordPress version under 4.5 ?

Prior to 4.5.0, the first parameter of get_terms() was a taxonomy or list of taxonomies:

 $terms = get_terms( 'post_tag', array( 'hide_empty' => false, ) ); 

Since 4.5.0, taxonomies should be passed via the 'taxonomy' argument in the $args array:

 $terms = get_terms( array( 'taxonomy' => 'post_tag', 'hide_empty' => false, ) ); 

About get_terms()

In your case, remove taxonomy from $args and

$terms = get_terms('category', $args);

Answer 2

Provide the taxonomy arg:

$args = array(
    'taxonomy' => 'your_taxonomy',
    'parent' => 2818,
    'hide_empty' => false
);