CMB2 With Multidimensional Support

README.md

With this way, you must extends CMB2 class:

A class will be handle multi-dimensional data (almost code is taken from WP_Customize_Setting class)

$metabox = new Our_CMB2(array(
  'id' => 'our-metabox',
  // ....
));

$metabox->add_field(array(
  // ...
));

Multidimensional.php

<?php

class Multidimensional {
	/**
	 * Return item in array with multidimensional support.
	 *
	 * @param  array  $array
	 * @param  string $keys
	 * @param  mixed  $default
	 * @return string
	 */
	public static function find( $array, $keys, $default = null ) {
		if ( isset( $array[ $keys ] ) ) {
			return $array[ $keys ];
		}

		$id_data = static::split( $keys );
		if ( empty( $id_data['keys'] ) || empty( $array[ $id_data['base'] ] ) ) {
			return $default;
		}

		return static::get( $array[ $id_data['base'] ], $id_data['keys'], $default );
	}

	/**
	 * Get split id_data for multidimensional.
	 *
	 * @param  string $id
	 * @return array
	 */
	public static function split( $id ) {
		$id_data['keys'] = preg_split( '/\[/', str_replace( ']', '', $id ) );
		$id_data['base'] = array_shift( $id_data['keys'] );

		return $id_data;
	}

	/**
	 * Will attempt to fetch a specific value from a multidimensional array.
	 *
	 * @param  array  $root
	 * @param  string $keys
	 * @param  mixed  $default
	 * @return mixed|null
	 */
	public static function get( $root, $keys, $default = null ) {
		if ( empty( $keys ) ) { // If there are no keys, test the root.
			return isset( $root ) ? $root : $default;
		}

		$result = static::multidimensional( $root, $keys );
		return isset( $result ) ? $result['node'][ $result['key'] ] : $default;
	}

	/**
	 * Will attempt to check if a specific value in a multidimensional array is set.
	 *
	 * @param  array  $root
	 * @param  string $keys
	 * @return bool
	 */
	public static function has( $root, $keys ) {
		$result = static::get( $root, $keys );
		return isset( $result );
	}

	/**
	 * Will attempt to replace a specific value in a multidimensional array.
	 *
	 * @param  array  $root
	 * @param  string $keys
	 * @return mixed
	 */
	public static function delete( &$root, $keys ) {
		$result = static::multidimensional( $root, $keys );

		if ( isset( $result ) ) {
			unset( $result['node'][ $result['key'] ] );
		}

		return $root;
	}

	/**
	 * Will attempt to replace a specific value in a multidimensional array.
	 *
	 * @param  array  $root
	 * @param  string $keys
	 * @param  mixed  $value
	 * @return mixed
	 */
	public static function replace( $root, $keys, $value ) {
		if ( ! isset( $value ) ) {
			return $root;
		} elseif ( empty( $keys ) ) { // If there are no keys, we're replacing the root.
			return $value;
		}

		$result = static::multidimensional( $root, $keys, true );

		if ( isset( $result ) ) {
			$result['node'][ $result['key'] ] = $value;
		}

		return $root;
	}

	/**
	 * Multidimensional helper function.
	 *
	 * @param array  $root
	 * @param string $keys
	 * @param bool   $create
	 * @return array|void
	 */
	protected static function multidimensional( &$root, $keys, $create = false ) {
		if ( $create && empty( $root ) ) {
			$root = array();
		}

		if ( ! isset( $root ) || empty( $keys ) ) {
			return;
		}

		$last = array_pop( $keys );
		$node = &$root;

		foreach ( $keys as $key ) {
			if ( $create && ! isset( $node[ $key ] ) ) {
				$node[ $key ] = array();
			}

			if ( ! is_array( $node ) || ! isset( $node[ $key ] ) ) {
				return;
			}

			$node = &$node[ $key ];
		}

		if ( $create ) {
			if ( ! is_array( $node ) ) {
				// Account for an array overriding a string or object value.
				$node = array();
			}

			if ( ! isset( $node[ $last ] ) ) {
				$node[ $last ] = array();
			}
		}

		if ( ! isset( $node[ $last ] ) ) {
			return;
		}

		return array(
			'root' => &$root,
			'node' => &$node,
			'key'  => $last,
		);
	}
}

Our_CMB2.php

<?php

class Our_CMB2 extends CMB2 {
  	/**
	 * Overrite CMB2 process and save form fields.
	 */
	public function process_fields() {
		$this->pre_process();

		// Remove the show_on properties so saving works
		$this->prop( 'show_on', array() );

		// save field ids of those that are updated
		$this->updated = array();

		foreach ( $this->prop( 'fields' ) as $field_args ) {
            // Magic is here!
			// Fake $this->data_to_save for support multi-dimensional.
			// If see a multidimensional-like, just add a parsed data with name
			// same as field ID. So we can easy access to multi-dimensional data.
			if ( strpos( $args['id'], '[' ) ) {
				$this->data_to_save[ $args['id'] ] = Multidimensional::find( $this->data_to_save, $args['id'], '' );
			}

			$this->process_field( $field_args );
		}
	}
}

Our_CMB2_Hooks.php

<?php

class Our_CMB2_Hooks {
	/**
	 * Init hooks.
	 */
	public function init() {
		// Support multidimensional fields.
		add_filter( 'cmb2_override_meta_save', array( $this, 'multidimensional_save_data' ), 10, 4 );
		add_filter( 'cmb2_override_meta_value', array( $this, 'multidimensional_get_data' ), 10, 4 );
		add_filter( 'cmb2_override_meta_remove', array( $this, 'multidimensional_remove_data' ), 10, 4 );
	}

	/**
	 * Filter whether to override saving of meta value.
	 *
	 * @param null|bool  $check      Whether to allow updating metadata for the given type.
	 * @param array      $args       Array of data about current field including.
	 * @param array      $field_args All field argument.
	 * @param CMB2_Field $field      This field objec.
	 * @return mixed
	 */
	public function multidimensional_save_data( $check, $args, $field_args, $field ) {
		$no_override = null;
		$id_data = Multidimensional::split( $args['field_id'] );

		// Tell CMB2 that we no override value.
		if ( empty( $id_data['keys'] ) ) {
			return $no_override;
		}

		// Options page updating...
		if ( 'options-page' === $args['type'] || empty( $args['id'] ) ) {
			$options = cmb2_options( $args['id'] )->get( $id_data['base'], array() );
			$repace_value = $args['value'];

			if ( ! $args['single'] ) {
				$repace_value = Multidimensional::get( $options, $id_data['keys'], array() );
				$repace_value[] = $args['value'];
				$repace_value = array_unique( $repace_value );
			}

			$update_values = Multidimensional::replace( $options, $id_data['keys'], $repace_value );
			return cmb2_options( $args['id'] )->update( $id_data['base'], $update_values, false, true );
		}

		// Update metadata...
		// NOTE: Maybe have bugs in this case, see: CMB2_Field::update_data().
		$metadata = get_metadata( $args['type'], $args['id'], $id_data['base'], true );

		// Delete meta if we have an empty array.
		if ( is_array( $args['value'] ) && empty( $args['value'] ) ) {
			$update_values = Multidimensional::delete( $metadata, $id_data['keys'] );
		} else {
			$update_values = Multidimensional::replace( $metadata, $id_data['keys'], $args['value'] );
		}

		return update_metadata( $args['type'], $args['id'], $id_data['base'], $update_values );
	}

	/**
	 * Filter whether to override saving of meta value.
	 *
	 * @param null|bool  $delete     Whether to allow metadata deletion of the given type.
	 * @param array      $args       Array of data about current field.
	 * @param int|string $field_args All field arguments.
	 * @param CMB2_Field $field      CMB2_Field object.
	 * @return mixed
	 */
	public function multidimensional_remove_data( $delete, $args, $field_args, $field ) {
		$no_override = null;
		$id_data = Multidimensional::split( $args['field_id'] );

		// Tell CMB2 that we no override value.
		if ( empty( $id_data['keys'] ) ) {
			return $no_override;
		}

		// Handler delete options.
		if ( 'options-page' === $args['type'] || empty( $args['id'] ) ) {
			$options = cmb2_options( $args['id'] )->get( $id_data['base'], array() );

			Multidimensional::delete( $options, $id_data['keys'] );

			return cmb2_options( $args['id'] )->update( $id_data['base'], $options, false, true );
		}

		// Handler delete metadata.
		$metadata = get_metadata( $args['type'], $args['id'], $id_data['base'], true );

		Multidimensional::delete( $metadata, $id_data['keys'] );

		return update_metadata( $args['type'], $args['id'], $id_data['base'], $metadata );
	}

	/**
	 * Filter whether to override saving of meta value.
	 *
	 * @param null|bool  $value      The meta value should return.
	 * @param int|string $object_id  Object ID.
	 * @param array      $args       An array of arguments for retrieving data.
	 * @param CMB2_Field $field      CMB2_Field object.
	 * @return mixed
	 */
	public function multidimensional_get_data( $value, $object_id, $args, $field ) {
		$no_override = 'cmb2_field_no_override_val';
		$id_data = Multidimensional::split( $args['field_id'] );

		// Tell CMB2 that we no override value.
		if ( empty( $id_data['keys'] ) ) {
			return $no_override;
		}

		if ( 'options-page' === $args['type'] ) {
			$metadata = cmb2_options( $args['id'] )->get( $id_data['base'] );
		} else {
			// NOTE: Maybe have bugs in this case, see: CMB2_Field::get_data().
			$metadata = get_metadata( $args['type'], $args['id'], $id_data['base'], true );
		}

		return Multidimensional::get( $metadata, $id_data['keys'] );
	}
}