我想知道这是否适用于您：

add_action( \'add_attachment\', function( $attachment_id ){
    $a = get_post( $attachment_id );
    if ( is_object( $a ) && \'image\' === substr( $a->post_mime_type, 0, 5 ) )
        wp_insert_attachment( array( \'ID\' => $a->ID, \'post_excerpt\' => $a->post_content ) );

});

add_action( \'add_attachment\', function( $attachment_id ){
    global $wpdb;
    if( ! empty( $attachment_id ) )
        $wpdb->query( $wpdb->prepare( "UPDATE $wpdb->posts 
                                       SET post_excerpt = post_content 
                                       WHERE ID = %d LIMIT 1", $attachment_id ) );

});