Should custom meta boxes be able to output shortcodes the same as WordPress’ native post editor?

Simply put: Should custom meta boxes be able to output shortcodes the same way as WordPress’ native post editor?

Reason I ask is because Ive created my own custom meta box for inputting a shortcode from the Cart66 plugin in order to output an “Add To Cart” button but when I try – it only prints the text from the shortcode rather than rendering the actual button.

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My current meta box:

<?php
//////////////////////////////////////////////////////////////////////
// Register Custom Post Type Meta Box -- Add To Cart Button Field   //
//////////////////////////////////////////////////////////////////////
add_action( 'add_meta_boxes', 'store_button_meta_box_add' );
function store_button_meta_box_add()
{
    add_meta_box( 'epr_store_button_meta_id', 'Add To Cart Button [shortcode]', 'store_button_meta_box_cb', 'epr_store', 'side', 'high' );
}

function store_button_meta_box_cb( $post )
{
    $values = get_post_custom( $post->ID );
    $button = isset( $values['meta_box_button_shortcode'] ) ? esc_attr( $values['meta_box_button_shortcode'][0] ) : '';
    wp_nonce_field( 'my_meta_box_nonce', 'meta_box_nonce' );
    ?>
    <p>
        <textarea name="meta_box_button_shortcode" id="meta_box_button_shortcode" row="5" style="width:100%; height:100px;text-align:left;"><?php echo esc_textarea($button); ?></textarea>
    </p>
    <?php   
}


add_action( 'save_post', 'epr_button_meta_box_save' );
function epr_button_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' ) ) 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['meta_box_button_shortcode'] ) )
        update_post_meta( $post_id, 'meta_box_button_shortcode', wp_kses( $_POST['meta_box_button_shortcode'], $allowed ) );
}
?>

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1 comment

  1. Short answer: no.

    Shortcodes are for injecting content directly in the Post Content, by the user, via the Post Edit screen.

    If your data are coming from a metabox, you have other, better, more efficient, and easier-to-control means of injecting content into the Post Content: primarily, the the_content filter (for general usage), or custom action hooks (for Themes that provide them).

    Using the the_content filter to add your code is simple:

    function my_plugin_filter_the_content( $content ) {
        // Get post custom meta
        $values = get_post_custom( $post->ID );
        // Determine if shortcode meta is set
        $my_custom_content = isset( $values['meta_box_button_shortcode'] ) ? esc_attr( $values['meta_box_button_shortcode'][0] ) : '';
        // Tell WordPress to execute the shortcode
        $custom_shortcode_output = do_shortcode( $my_custom_content );
        // Append the executed shortcode to $content
        $content .= $custom_shortcode_output;
        // Return modified $content
        return $content;
    }
    add_filter( 'the_content', 'my_plugin_filter_the_content' );
    

    No need for a shortcode.

    Also, using a filter, you don’t have to worry about your shortcode being left orphaned if the user deactivates your Plugin.

    Note that, if you need to output a specific shortcode, you can use do_shortcode( '[shortcode_name att="value"]' )