Mini plugin to allow specifying no default gateway in Easy Digital Downloads.

edd-no-default-gateway.php

<?php
/**
 * Mini plugin to allow specifying no default gateway in Easy Digital Downloads.
 *
 * @package EDDNoDefaultGateway
 * @since 1.0.0
 *
 * @wordpress-plugin
 * Plugin Name: EDD No Default Gateway
 * Plugin URI:  https://gist.github.com/felixarntz/f9ada0ffb92d6b2e880c7dd0f826b486
 * Description: Mini plugin to allow specifying no default gateway in Easy Digital Downloads.
 * Version:     1.0.0
 * Author:      Felix Arntz
 * Author URI:  https://leaves-and-love.net
 * License:     GNU General Public License v3
 * License URI: http://www.gnu.org/licenses/gpl-3.0.html
 */

function edd_ndg_add_default_gateway_option_none( $gateway_settings ) {
  if ( ! empty( $gateway_settings['main']['default_gateway']['options'] ) ) {
    
    // Add an option to select 'None' in the default gateway dropdown.
    $gateway_settings['main']['default_gateway']['options'] = array_merge( array(
      '' => array(
        'admin_label'    => __( 'None', 'easy-digital-downloads' ),
        'checkout_label' => __( 'None', 'easy-digital-downloads' ),
      ),
    ), $gateway_settings['main']['default_gateway']['options'] );
  }

  return $gateway_settings;
}
add_filter( 'edd_settings_gateways', 'edd_ndg_add_default_gateway_option_none' );

function edd_ndg_allow_no_default_gateway( $gateway ) {
  $original_option = edd_get_option( 'default_gateway', '' );
  
  // Allow an empty option value to be valid.
  if ( empty( $original_option ) ) {
    return $original_option;
  }

  return $gateway;
}
add_filter( 'edd_default_gateway', 'edd_ndg_allow_no_default_gateway' );

function edd_ndg_maybe_prevent_default_gateway_load( $script_vars ) {
  if ( edd_is_checkout() ) {
    $chosen_gateway = edd_get_chosen_gateway();

    // This variable needs to be set to 0 so that no default gateway loads in JS.
    if ( empty( $chosen_gateway ) ) {
      $script_vars['is_checkout'] = '0';
    }
  }

  return $script_vars;
}
add_filter( 'edd_ajax_script_vars', 'edd_ndg_maybe_prevent_default_gateway_load' );

function edd_ndg_maybe_print_default_gateway_free_purchase_fix() {
  if ( ! edd_is_checkout() ) {
    return;
  }

  $chosen_gateway = edd_get_chosen_gateway();
  if ( ! empty( $chosen_gateway ) ) {
    return;
  }
  
  // The following script ensures that the purchase form is manually loaded when a purchase is free.
  // Without this, it is impossible to complete such a purchase.
  ?>
  <script type="text/javascript">
    ( function() {
      var is_free = false;

      jQuery( document.body ).on( 'edd_discount_applied', function( e, discount ) {
        if ( '0.00' == discount.total_plain ) {
          is_free = true;

          if ( window.edd_load_gateway ) {
            window.edd_load_gateway( 'manual' );
          }
        } else if ( is_free ) {
          is_free = false;

          jQuery( '#edd_purchase_form_wrap' ).html( '' );
        }
      });
    })();
  </script>
  <?php
}
add_action( 'wp_footer', 'edd_ndg_maybe_print_default_gateway_free_purchase_fix', 9999 );