Function to Download External Images to My Site

Question

I display images on my site from other sites. The URL is saved in a custom field named couv.

I would like to download these pictures on to my site and create a new custom field with the new value couv2.

I tried to do this with the following code in my functions.php file but it doesn't work.

function downloadcouv() {
    global $wp_query;
    $lien = get_post_meta(
        $wp_query->queried_object->ID,
        "couv",
        true
    );
    $uploads = wp_upload_dir();
    $reg = "#([^/]*)$#";
    $chaine = $lien;
    preg_match( $reg, $chaine, $res );
    $couv = $uploads['baseurl'] . '/couv/' . $res[1];
    copy( $lien, $couv );
    add_post_meta(
        $wp_query->queried_object->ID,
        "couv2",
        $couv,
        true
    );
}
add_action( 'save_post', 'downloadcouv' );

Edit: I made this change but it is still not working.

function downloadcouv() {
    global $wp_query;
    $post_id = $wp_query->queried_object->ID;
    $lien = get_post_meta(
        $post_id,
        "couv",
        true
    );
    $desc = $post_title; 
    $couv = media_sideload_image(
        $lien,
        $post_id,
        $desc
    );
    add_post_meta(
        $post_title,
        "couv2",
        $couv,
        true
    );
}
add_action( 'save_post', 'downloadcouv' );

Answer 1

Here is a solution to upload a copy of the image saved as a URL in a custom field into a local directory on your site. This will not add the image to the media library and is meant as more of a caching mechanism.

You should always be sure that you have permission to use images from other sources before you use them. Only use this code for good!

function downloadcouv( $post_id, $post, $update ) {

    // Update the post's metadata.

    if ( isset( $_POST['couv'] ) ) {

        // Get the upload directory
        $upload_dir = wp_upload_dir();

        // Make sure that the image URL is actually a URL
        if ( FALSE !== filter_var($_POST['couv'], FILTER_VALIDATE_URL) ) {

            // Get the file extension
            $ext = pathinfo($_POST['couv'], PATHINFO_EXTENSION);

            // Copy the file from the url to a local directory
            copy( $backdrop, $upload_dir['basedir'] . '/site-img-' . $post_id . '.' . $ext );

            // Update the post meta with the URL to the uploaded image
            update_post_meta( $post_id, 'couv2', $upload_dir['basedir'] . '/site-img-' . $post_id . '.' . $ext );

        }

    }

}
add_action( 'save_post', 'downloadcouv', 10, 3 );