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I am trying to write a plugin to allow using coupons that are stored on a separate system and can be accessed through a Web API. To that end, I want to use the filter woocommerce_get_shop_coupon_data.

The source code is

$coupon = apply_filters( 'woocommerce_get_shop_coupon_data', false, $this->code )

My code in the plugin constructor:

add_filter('woocommerce_get_shop_coupon_data', array($this, 'filter_woocommerce_get_shop_coupon_data'));

And the function:

public function filter_woocommerce_get_shop_coupon_data($arg1, $arg2) {
    var_dump($arg1);
    var_dump($arg2);
    return null;
}

And what I'm getting is bool(false) NULL, i.e. the second arg which is supposed to be the coupon code is null. I have no idea what is happening here.

1

You need to tell add_filter how many arguments it accepts (2) example:

add_filter('woocommerce_get_shop_coupon_data', array( $this, 'filter_woocommerce_get_shop_coupon_data' ), 10, 2 );

Be sure to enable WP_Debug - http://wpexplorer-themes.com/total/docs/enabling-wp-debug/ - on your server, because you should have gotten an error when trying to do this without the added argument.

Also I highly recommend using static classes when dealing with filters for easiser modification by developers using child themes or extra plugins. Example:

add_filter( 'woocommerce_get_shop_coupon_data', array( 'YOUR_CLASS_NAME', 'filter_woocommerce_get_shop_coupon_data' ), 10, 2 );

public static function filter_woocommerce_get_shop_coupon_data( $arg1, $arg2 ) {
    var_dump($arg1);
    var_dump($arg2);
    return null;
}

This way a developer can always use this if needed:

remove_filter( 'woocommerce_get_shop_coupon_data', array( 'YOUR_CLASS_NAME', 'filter_woocommerce_get_shop_coupon_data' ), 10, 2 );

When using $this WordPress assigns a dynamic name and it's harder to modify things if needed. Just a tip. Maybe not for this plugin bug for others ;)

  • I highly recommend using static functions though for your class - this way it's easier for a developer to remove your code. See my edited response ;) – WPExplorer Mar 6 '17 at 3:28
  • Thank you!!! And the 10 is its priority, am I right? – lfk Mar 6 '17 at 3:46
  • Yes 10 is the priority ;) But you can use anything - if 10 isn't working use 20 maybe. If this is intended to override ANYTHING you can also use PHP_INT_MAX – WPExplorer Mar 6 '17 at 16:35

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