Create multiple coupons programmatically in WooCommerce 3+

Your code is not applying (or adding a coupon)… It's "creating" a new coupon!.

since WooCommerce 3, your code is a bit outdated. Instead you should better use the available WC_Coupon setter methods like in the code below.

As you are generating the coupon code name with wp_generate_password() function, you need to check that the new generated coupon code doesn't exist yet, as WooCommerce requires that each coupons code name is unique (see below a custom function for that purpose).

To generate multiple coupons, you can just make a foreach loop that will iterate through a defined array of coupons costs.

1). First a utility function to generate unique non existing coupon names (coupon codes):

// Utility function that generate a non existing coupon code (as each coupon code has to be unique)function generate_coupon_code() {    global $wpdb;        // Get an array of all existing coupon codes    $coupon_codes = $wpdb->get_col("SELECT post_name FROM $wpdb->posts WHERE post_type = 'shop_coupon'");        for ( $i = 0; $i < 1; $i++ ) {        $generated_code = strtolower( wp_generate_password( 15, false ) );                // Check if the generated code doesn't exist yet        if( in_array( $generated_code, $coupon_codes ) ) {            $i--; // continue the loop and generate a new code        } else {            break; // stop the loop: The generated coupon code doesn't exist already        }    }    return $generated_code;}   

Code goes in functions.php file of your active child theme (or active theme).

2). Now the code with the foreach loop WC_Coupon setter methods to generate multiple coupons based on a defined array of coupon discount amounts (replaced non existing 'store_credit' coupon type by 'fixed_cart'):

// Here below define your coupons discount amount$discount_amounts = array( 12, 18, 15, 10 );// Set some coupon data by default$date_expires     = date('Y-m-d', strtotime('+371 days'));$discount_type    = 'fixed_cart'; // 'store_credit' doesn't exist// Loop through the defined array of coupon discount amountsforeach( $discount_amounts as $coupon_amount ) {    // Get an emty instance of the WC_Coupon Object    $coupon = new WC_Coupon();        // Generate a non existing coupon code name    $coupon_code  = generate_coupon_code();    // Set the necessary coupon data (since WC 3+)    $coupon->set_code( $coupon_code );    $coupon->set_discount_type( $discount_type );    $coupon->set_amount( $coupon_amount );        $coupon->set_date_expires( $date_expires );    $coupon->set_usage_limit( 1 );    $coupon->set_individual_use( true );    // Create, publish and save coupon (data)    $coupon->save();}

Tested and works.

Notes:

• "expiry_date" property is replaced by "date_expires"
• apply_before_tax property doesn't exist anymore
• "free_shipping" is always set to false (no) by default