Description

Add the timezone offset on the saved Datetime object and remove it on field load.

Note: this PR needs improvement (see high risk below)

Motivation and Context

Currently, the timezone offset is only applied to the UTC saved date. This PR applies the offset on the stored Datetime object as well.
Fixes #1465

Risk Level

Low risk - small changes, all related to the text_datetime_timestamp_timezone field.

High risk that needs to be resolved: Existing data will also receive an offset modification on field load. This means the input value changes when the user loads the page, the new value is saved when the user saves the page.

Testing procedure

1. Add code sample below to your environment
2. Create a new post
3. See how the Date is not saved correctly
4. Apply the changes in this PR

The code sample below shows the issue:

<?php
/**
 * Plugin Name: CMB2 text_datetime_timestamp_timezone Test
 */

add_action(
	'cmb2_admin_init',
	function() {

		$details = new_cmb2_box(
			array(
				'id'           => 'cmb2_test',
				'title'        => __( 'Details', 'cmb2' ),
				'object_types' => array( 'post' ),
			)
		);

		$details->add_field(
			array(
				'name'        => 'Date',
				'type'        => 'text_datetime_timestamp_timezone',
				'id'          => 'date',
				'after_field' => function() {
					$serialized_date = get_post_meta( get_the_ID(), 'date', true );
					if ( ! empty( $serialized_date ) ) {
						$date = maybe_unserialize( $serialized_date );
						echo '<br><br>Date/Time: ' . $date->format( get_option( 'date_format' ) . ' ' . get_option( 'time_format' ) . ' e' ) . '<br>';

					}
				},
			)
		);

	}
);

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the code style of this project.
• My code and pull requests meets the Contributing guidelines.

Screenshots

Screenshot of UTC saved date and saved object after save in the current develop branch:

Screenshot of UTC saved date and saved object after save in this branch: