Using WordPress ‘default_{$meta_type}_metadata’ PHP filter

The default_{$meta_type}_metadata WordPress PHP filter allows you to modify the default metadata value for a specified meta key and object, depending on the meta object type (post, comment, term, user, or any other type with an associated meta table).

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Usage

add_filter('default_post_metadata', 'my_custom_default_metadata', 10, 5);

function my_custom_default_metadata($value, $object_id, $meta_key, $single, $meta_type) {
  // your custom code here
  return $value;
}

Parameters

• $value (mixed): The value to return, either a single metadata value or an array of values depending on the value of $single.
• $object_id (int): ID of the object metadata is for.
• $meta_key (string): Metadata key.
• $single (bool): Whether to return only the first value of the specified $meta_key.
• $meta_type (string): Type of object metadata is for. Accepts ‘post’, ‘comment’, ‘term’, ‘user’, or any other object type with an associated meta table.

More information

See WordPress Developer Resources: default_{$meta_type}_metadata

Examples

Set default post metadata

Set a default value for a custom post meta key called ‘post_views’.

add_filter('default_post_metadata', 'set_default_post_views', 10, 5);

function set_default_post_views($value, $object_id, $meta_key, $single, $meta_type) {
  if ($meta_key === 'post_views') {
    $value = 0;
  }
  return $value;
}

Set default user metadata

Set a default value for a custom user meta key called ‘user_bio’.

add_filter('default_user_metadata', 'set_default_user_bio', 10, 5);

function set_default_user_bio($value, $object_id, $meta_key, $single, $meta_type) {
  if ($meta_key === 'user_bio') {
    $value = 'New user, no bio yet!';
  }
  return $value;
}

Set default term metadata

Set a default value for a custom term meta key called ‘term_icon’.

add_filter('default_term_metadata', 'set_default_term_icon', 10, 5);

function set_default_term_icon($value, $object_id, $meta_key, $single, $meta_type) {
  if ($meta_key === 'term_icon') {
    $value = 'default-icon';
  }
  return $value;
}

Set default comment metadata

Set a default value for a custom comment meta key called ‘comment_rating’.

add_filter('default_comment_metadata', 'set_default_comment_rating', 10, 5);

function set_default_comment_rating($value, $object_id, $meta_key, $single, $meta_type) {
  if ($meta_key === 'comment_rating') {
    $value = 0;
  }
  return $value;
}

Set default metadata for custom object type

Set a default value for a custom object type meta key called ‘custom_object_color’.

add_filter('default_custom_object_metadata', 'set_default_custom_object_color', 10, 5);

function set_default_custom_object_color($value, $object_id, $meta_key, $single, $meta_type) {
  if ($meta_key === 'custom_object_color') {
$value = 'blue';
}
return $value;
}

With these examples, you can set default metadata values for various object types in WordPress. Adjust the filter names, meta keys, and default values according to your specific use case.