How to save a checkbox meta box in WordPress?

Question

I\'m trying to add a checkbox into my custom meta box in WordPress and I ran into a problem with saving it - whenever I check the checkbox and update the post/page, it comes

Answer 1

I had trouble with this previously and here is how I solved it.

First, creating the Checkbox.

<?php
function sl_meta_box_sidebar(){
    global $post;
    $custom = get_post_custom($post->ID);
    $sl_meta_box_sidebar = $custom["sl-meta-box-sidebar"][0]; 
?>

<input type="checkbox" name="sl-meta-box-sidebar" <?php if( $sl_meta_box_sidebar == true ) { ?>checked="checked"<?php } ?> />  Check the Box.
<?php } ?>

Next, saving.

<?php
add_action('save_post', 'save_details');

function save_details($post_ID = 0) {
    $post_ID = (int) $post_ID;
    $post_type = get_post_type( $post_ID );
    $post_status = get_post_status( $post_ID );

    if ($post_type) {
    update_post_meta($post_ID, "sl-meta-box-sidebar", $_POST["sl-meta-box-sidebar"]);
    }
   return $post_ID;
} ?>