February 12, 2011 
Definition:
function media_handle_sideload($file_array, $post_id, $desc = null, $post_data = array() {}
This handles a sideloaded file in the same way as an uploaded file is handled by media_handle_upload()
Parameters
- array $file_array: Array similar to a $_FILES upload array
- int $post_id: The post ID the media is associated with
- string $desc: Description of the sideloaded file
- array $post_data: allows you to overwrite some of the attachment
Return values
returns:ID of the attachment or a WP_Error on failure
Source code
function media_handle_sideload($file_array, $post_id, $desc = null, $post_data = array()) {
$overrides = array('test_form'=>false);
$file = wp_handle_sideload($file_array, $overrides);
if ( isset($file['error']) )
return new WP_Error( 'upload_error', $file['error'] );
$url = $file['url'];
$type = $file['type'];
$file = $file['file'];
$title = preg_replace('/\.[^.]+$/', '', basename($file));
$content = '';
// use image exif/iptc data for title and caption defaults if possible
if ( $image_meta = @wp_read_image_metadata($file) ) {
if ( trim( $image_meta['title'] ) && ! is_numeric( sanitize_title( $image_meta['title'] ) ) )
$title = $image_meta['title'];
if ( trim( $image_meta['caption'] ) )
$content = $image_meta['caption'];
}
$title = isset($desc) ? $desc : '';
// Construct the attachment array
$attachment = array_merge( array(
'post_mime_type' => $type,
'guid' => $url,
'post_parent' => $post_id,
'post_title' => $title,
'post_content' => $content,
), $post_data );
// This should never be set as it would then overwrite an existing attachment.
if ( isset( $attachment['ID'] ) )
unset( $attachment['ID'] );
// Save the attachment metadata
$id = wp_insert_attachment($attachment, $file, $post_id);
if ( !is_wp_error($id) )
wp_update_attachment_metadata( $id, wp_generate_attachment_metadata( $id, $file ) );
return $id;
}
2349
A HitchHackers guide through WordPress 
function attach_image_url($file, $post_id, $desc = null) {
require_once(ABSPATH . “wp-admin” . ‘/includes/image.php’);
require_once(ABSPATH . “wp-admin” . ‘/includes/file.php’);
require_once(ABSPATH . “wp-admin” . ‘/includes/media.php’);
if ( ! empty($file) ) {
// Download file to temp location
$tmp = download_url( $file );
// Set variables for storage
// fix file filename for query strings
preg_match(‘/[^\?]+\.(jpg|JPG|jpe|JPE|jpeg|JPEG|gif|GIF|png|PNG)/’, $file, $matches);
$file_array[‘name’] = basename($matches[0]);
$file_array[‘tmp_name’] = $tmp;
// If error storing temporarily, unlink
if ( is_wp_error( $tmp ) ) {
@unlink($file_array[‘tmp_name’]);
$file_array[‘tmp_name’] = ”;
}
// do the validation and storage stuff
$id = media_handle_sideload( $file_array, $post_id, $desc );
// If error storing permanently, unlink
if ( is_wp_error($id) ) {@unlink($file_array[‘tmp_name’]);}
add_post_meta($post_id, ‘_thumbnail_id’, $id, true);
}
}