Add Custom Campaign And Donation Field

/**

 * In this example, a new email field is added which can be used both in

 * campaign emails and donation emails. The field gets a value for a specific

 * campaign, which in the case of a donation-specific email, will be the

 * campaign that received the donation.

 */

/**

 * Display the field based on a campaign-specific value.

 *

 * This field can be used for any campaign-related emails or

 * donation-related emails. If an email is not related to either of

 * those, nothing will be shown.

 *

 * @param  string           $value The default value to show.

 * @param  array            $args  Set of additional arguments available.

 * @param  Charitable_Email $email The email object.

 * @return string

 */

function ed_charitable_get_email_field_value( $value, $args, $email ) {

	$campaign = $email->get_campaign();

	if ( is_null( $campaign ) ) {

		$donation = $email->get_donation();

		if ( is_null( $donation ) ) {

			return '';

		}

		$campaign_id = current( $donation->get_campaign_donations() )->campaign_id;

		$campaign    = charitable_get_campaign( $campaign_id );

	}

    return $campaign->get( 'some_field' );

}

/**

 * Register an email field.

 *

 * @param  array $fields All the registered fields.

 * @return array

 */

function ed_charitable_add_email_field( $fields ) {

    $fields['some_field'] = array(

        'description' => 'A description of this field',

        'preview'     => 'Placeholder value',

        'callback'    => 'ed_charitable_get_email_field_value',

    );

    return $fields;

}

add_filter( 'charitable_email_campaign_fields', 'ed_charitable_add_email_field' );

add_filter( 'charitable_email_donation_fields', 'ed_charitable_add_email_field' );