The attachment_submitbox_misc_actions WordPress PHP action fires after the ‘Uploaded on’ section of the Save meta box in the attachment editing screen.
Usage
add_action('attachment_submitbox_misc_actions', 'your_custom_function');
function your_custom_function($post) {
// your custom code here
}
Parameters
$post(WP_Post): The WP_Post object for the current attachment.
More information
See WordPress Developer Resources: attachment_submitbox_misc_actions
Examples
Add a Custom Field to the Attachment Submit Box
Add a custom field to the attachment submit box and save its value.
add_action('attachment_submitbox_misc_actions', 'add_custom_field');
function add_custom_field($post) {
$custom_value = get_post_meta($post->ID, '_custom_field', true);
echo '<label for="custom_field">Custom Field: </label>';
echo '<input type="text" id="custom_field" name="custom_field" value="' . esc_attr($custom_value) . '" />';
}
add_action('edit_attachment', 'save_custom_field');
function save_custom_field($post_id) {
if (isset($_POST['custom_field'])) {
update_post_meta($post_id, '_custom_field', $_POST['custom_field']);
}
}
Display Attachment File Size
Display the file size of the attachment in the submit box.
add_action('attachment_submitbox_misc_actions', 'display_file_size');
function display_file_size($post) {
$file_path = get_attached_file($post->ID);
$file_size = filesize($file_path);
echo '<p>File Size: ' . size_format($file_size) . '</p>';
}
Add a Custom Button
Add a custom button to the attachment submit box.
add_action('attachment_submitbox_misc_actions', 'add_custom_button');
function add_custom_button($post) {
echo '<input type="button" class="button" id="custom_button" value="Custom Button" />';
}
Display Attachment Dimensions
Display the dimensions of an image attachment in the submit box.
add_action('attachment_submitbox_misc_actions', 'display_image_dimensions');
function display_image_dimensions($post) {
if (wp_attachment_is_image($post->ID)) {
$dimensions = wp_get_attachment_image_src($post->ID, 'full');
echo '<p>Dimensions: ' . $dimensions[1] . ' x ' . $dimensions[2] . ' px</p>';
}
}
Change Attachment Title Placeholder
Change the placeholder text of the attachment title input field.
add_action('attachment_submitbox_misc_actions', 'change_title_placeholder');
function change_title_placeholder($post) {
echo '<script>
document.getElementById("title").setAttribute("placeholder", "Custom Attachment Title");
</script>';
}