using custom tables with CMB2

custom-tables-cmb2.php

<?php

// I've copied and pasted then edited this without testing, apols for any errors. It's for illustrative purposes mainly :
// https://tharshetests.wordpress.com/2017/12/27/using-custom-tables-with-cmb2/
// The idea here is that I want to "methods" metaboxes which are going to be a repeatable group with the method itself 
// and whichever countries the metabox applies to. 
// So eg for a recipe, you'd have "cook the aubergine" in the UK and "cook the eggplant" in the US. 
// The methods are stored in custom tables (this is pretend, the code below doesn't do that)

// Adding the metaboxes happens as normal
add_action( 'cmb2_admin_init',  'mjj_add_methods_metaboxes' );
function mjj_add_methods_metaboxes(){
    // as normal
	$metabox = new_cmb2_box( array(
		'id'            => 'mjj_mthd_mb',
		'title'         => __( 'Methods', 'mjj' ),
		'context'       => 'normal',
		'priority'      => 'high',
		'show_names'    => true
	) );

	// as normal
	$method_group = $metabox->add_field( array(
		'id'          => '_mjj_methods',
		'type'        => 'group',
		'description' => __( 'Different countries have different words for things, so you might need more than one method', 'mjj' ),
		'options'     => array(
			'group_title'   => __( 'Method {#}', 'mjj' ), 
			'add_button'    => __( 'Add Another Method', 'mjj' ),
			'remove_button' => __( 'Remove Method', 'mjj' ),
		),
	) );

	// as normal
	$metabox->add_group_field( $method_group, array(
		'name' => 'Method',
		'id'   => 'method',
		'type' => 'textarea',
	) );
	
	// as normal
	$metabox->add_group_field( $method_group, array(
		'name'    => 'Countries',
		'desc'    => 'In which countries should this method be shown? (Only US, UK and AUS for now)',
		'id'      => 'countries',
		'type'    => 'multicheck',
		'options' => array(
			'US' => 'US',
			'UK' => 'UK',
			'AUS' => 'AUS',
		),
	) );
}

// This bit is to get the values and put them in the metaboxes on the post edit page.
// I could also hook into cmb2_override_meta_value and look for the _mjj_methods field id and only run this on that.
add_filter('cmb2_override__mjj_methods_meta_value', 'mjj_get_methods_custom_data', 10, 4);
function mjj_get_methods_custom_data( $dont_override, $object_id, $args, $cmb2_field_object ){
	// Below is getting my data, you can't really copy and paste this and have it work.
	// $mjj_methods = new MJJ_Methods;
	// $methods = $mjj_methods->get( array( 'object_id' => $object_id ) );
	
	// Ok, let's pretend that $methods got this:
	$methods = array(
		array(
	  		'method' => 'This is a method for the US and AUS'
	  		'countries' => array( 'US', 'AUS' )
	 	 ),
		array(
	  		'method' => 'This is a method for the UK'
	  		'countries' => array( 'UK' )
	  	)
	);
	
	return $methods;
}

// This saves the metaboxes.
// runs when the _mjj_methods goes to get updated / saved
add_filter('cmb2_override__mjj_methods_meta_save', 'mjj_save_methods_custom_data', 10, 4 );
function mjj_save_methods_custom_data( $check, $args, $field_args, $cmb2_field_object ){
	// each argument is a superset of the argument before :)
	// do all the custom saving bits here
	return 'something other than null'; // return something other than null
}

// This is a useful field to have on hand.
// add a hidden field in which to put the id -- I can use this with 'type' => 'mjj_hidden_field' and it works in repeatable groups
add_action( 'cmb2_render_mjj_hidden_field', 'mjj_hidden_field', 10, 5 );
function mjj_hidden_field( $field, $escaped_value, $object_id, $object_type, $field_type_object ){
	echo $field_type_object->input( array( 'type' => 'hidden' ) );
}

Nice. Thank you for this. Tell me, do you know why the call back function gets called for the total number of fields plus 1?