Meta Box Value not saving / populating?

Question

Ok, I have a meta box setup now that populates with the all the registered post types. That part works fine. But, upon selecting an option in the dropdown list, and saving / updating, the value shows the first choice when the page reloads. Also, does anyone know if get_post_types can exclude specific post types?

Here's my code:

    add_action( 'add_meta_boxes', 'cd_meta_box_add' );
    function cd_meta_box_add()
    {
add_meta_box( 'my-meta-box-id', 'My First Meta Box', 'cd_meta_box_cb', 'page', 'normal', 'high' );
    }

    function cd_meta_box_cb( $post )
    {
$values = get_post_custom( $post->ID );
$selected = isset( $values['my_meta_box_select'] ) ? esc_attr( $values['my_meta_box_select'][0] ) : '';
wp_nonce_field( 'my_meta_box_nonce', 'meta_box_nonce' );
?>

<p>
    <label for="my_meta_box_select">Post type: </label>
    <select name="my_meta_box_select" id="my_meta_box_select">
        <?php $post_types=get_post_types('', 'objects'); foreach ($post_types as $post_type): ?>
        <option value="<?php echo esc_attr($post_type->name);?>"  <?php selected( $selected, '$post_type->name' ); ?>><?php echo esc_html($post_type->label); selected ?></option>
        <?php endforeach; ?>
    </select>
</p>    


<?php   
    }


    add_action( 'save_post', 'cd_meta_box_save' );
    function cd_meta_box_save( $post_id )
    {
// Bail if we're doing an auto save
if( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) return;

// if our nonce isn't there, or we can't verify it, bail
if( !isset( $_POST['meta_box_nonce'] ) || !wp_verify_nonce( $_POST['meta_box_nonce'], 'my_meta_box_nonce' ) ) return;

// if our current user can't edit this post, bail
if( !current_user_can( 'edit_post', $post_id ) ) return;

// now we can actually save the data
$allowed = array( 
    'a' => array( // on allow a tags
        'href' => array() // and those anchords can only have href attribute
    )
);

// Probably a good idea to make sure your data is set

if( isset( $_POST['my_meta_box_select'] ) )
    update_post_meta( $post_id, 'my_meta_box_select', esc_attr( $_POST['my_meta_box_select'] ) );

    }

Answer 1

Variables do not expand inside single quotes, so this-- selected( $selected, '$post_type->name'-- is literally checking for a string that looks like '$post_type->name'. If you are saving the option names, it should work if you just remove the quotes (though I did not run your code to test that).

Your might be able to exclude what you want via the public and _builtin arguments to get_post_types, but if you are looking to exclude a particular type other than what those arguments will do, I don't see a way to do that directly, but there is a filter. It would likely be easier just to filter the post type out in your foreach loop though.