Cmb2: 'Default' parameter problem

[adesombergh]

Hi!

The problem:

Wordpress gets an error when you define the default parameter of a field to 'max' or 'Max'.

Example:

add_action( 'cmb2_init', 'yourprefix_register_demo_metabox' );
function yourprefix_register_demo_metabox() {

    $cmb = new_cmb2_box( array(
        'id'           => 'box_id',
        'title'        => 'Title',
    ) );

    $cmb->add_field( array(
            'name'    => 'field_one',
            'id'      => 'field_one',
            'type'    => 'text',
            'default' => 'max',
    ) );
        $cmb->add_field( array(
            'name'    => 'field_two',
            'id'      => 'field_two',
            'type'    => 'hidden',
            'default' => 'Max',
    ) );

}

The result:

Catchable fatal error: Object of class CMB2_Field could not be converted to string in /home/root/mysite.com/wp-includes/formatting.php on line 1025

[tw2113]

Not quite sure why, but it seems like in this case, "max" is turning into the default callback, aka default_cb in the args array deep in CMB2, instead of the default value.

I know that max is a PHP core function, and I was able to recreate similar issues with other PHP core functions.

That said, changing it to "Maximum" worked fine for me.

Overall feels like a real edge case, and some odd behavior truth be told.

[jtsternberg]

Yes, this is an unfortunate side-effect of allowing the 'default' field parameter to also be a callback. That functionality is now deprecated in favor of using the 'default_cb' field parameter, and my intention is to remove that functionality from the 'default' field parameter in a few releases, but need to give the deprecation enough time, since we try to be backwards compatible.

That being said, I'd suggest using a callback to define your default so that you can bypass the bug:

add_action( 'cmb2_init', 'yourprefix_register_demo_metabox' );
function yourprefix_register_demo_metabox() {

    $cmb = new_cmb2_box( array(
        'id'    => 'box_id',
        'title' => 'Title',
    ) );

    $cmb->add_field( array(
        'name'       => 'field_one',
        'id'         => 'field_one',
        'type'       => 'text',
        'default_cb' => 'yourprefix_set_default_to_max',
    ) );
    $cmb->add_field( array(
        'name'       => 'field_two',
        'id'         => 'field_two',
        'type'       => 'hidden',
        'default_cb' => 'yourprefix_set_default_to_max',
    ) );

}

function yourprefix_set_default_to_max() {
    return 'max';
}

[dameer]

The problem still persists. For over 3 years.

[toddbarnett]

I'm running into a similar issue with 'default' => 'Link', it's throwing an error in Xdebug.

$cmb->add_field( array(
        'name'       => __( 'Medium', 'cmb2' ),
        'desc'       => __( 'Link, Banner, CPC', 'cmb2' ),
        'id'         => 'utm_medium',
        'default'    => 'Link',
        'type'       => 'text'
    ) );

[tw2113]

What sort of error is being thrown for you @toddbarnett ?

[toddbarnett]

@tw2113 Warning: link() expects exactly 2 parameters, 3 given in CMB2_Base.php on line 315

[toddbarnett]

@tw2113 Looks like back in '16 you guys had a plan to remove 'default' and use 'default_cb' instead is that right? @jtsternberg comment is a little confusing he say's 'default' is to be replaced with 'default' but in his example, he has 'default_cb' and the docs still refer to 'default'? Furthermore, the error I'm facing only happens when there is no data saved to the post meta yet.

[jtsternberg]

Wow, good catch, can't believe no-one has pointed that out before. Fixed it. Also, please point me to the docs where it is default vs default_cb so I can update.

[jtsternberg]

Once you change to default_cb, you will not get that error.

[tw2113]

Justin has chimed in as well with his parts. Basically from what I see, it was being treated as a callback spot for the link() function over at https://www.php.net/manual/en/function.link.php.

[toddbarnett]

@tw2113, @jtsternberg, Wow, fast reply. You guys are awesome. Thank you!

(https://cmb2.io/docs/field-types#-types-text)

[jtsternberg]

Ah yah. So the 'default' property/usage will not go away... just the usage of it as a callback. If you want a callback for the default, you will need to use default_cb

[toddbarnett]

Okay, I ended up using 'default_cb' because having the word 'Link' as the 'default' text was throwing a PHP link() function error as Michael has pointed out.