Add Textbox To Donation Form

/**

 * Shows how to add a custom text box in a donation form.

 * In this example, we are adding a text box to collect a special referral code that the admin can read later.

 *

 * This snippet only works in Charitable 1.5 or above.

 *

 */

function wpchar_charitable_register_new_text_field() {

    /**

     * Define a new text field.

     */

	if ( ! class_exists("Charitable_Donation_Field" ) ) {

		return;

	};

    /* Create the Donation Field instance. */

    $field = new Charitable_Donation_Field(

        'my_custom_field',

        array(

            'label'          => __( 'Referral Code' ), // what text shows up in the donation form.

            'data_type'      => 'meta', 

            'value_callback' => false,

            'donation_form'  => array(

                'type'       => 'text',  // the type of field to show in the donation form (text, checkbox, etc.)

                'required'   => false,   // whether the field is required.

                'show_after' => 'phone', // the field to show this one after.

            ), 

            'admin_form'     => true,

            'show_in_meta'   => true,

            'show_in_export' => true,

            'email_tag'      => array( // the tag to use in email notifications (make false to not add this to tags.

                'description' => __( 'The custom field value' ),

            ),

        )

    );

    /* Register it. */

    charitable()->donation_fields()->register_field( $field );

}

add_action( 'init', 'wpchar_charitable_register_new_text_field' );