How to get coupons from email restrictions with efficiency in WooCommerce - php

Question

I have the following loop for getting Woocommerce coupons on a page within the my account section of a customers dashboard.
Currently we have 10k+ coupons and just by performing this loop, it's a huge drain on resources and not very efficient causing time outs. Are there any obvious ways in which I can improve the efficiency of it?
Is there a way I can limit the loop to the only search for emails in the "Allowed emails" field (as each coupon is tied to an email address)?
<?php $smart_coupons = get_posts( array(
'posts_per_page' => -1,
'orderby' => 'name',
'order' => 'desc',
'post_type' => 'shop_coupon',
'post_status' => 'publish'
) );
if ( $smart_coupons ) {
foreach( $smart_coupons as $smart_coupon) {
$strcode = strtolower($smart_coupon->post_title);
$full_coupon = new WC_Coupon( $strcode ); ?>
<?php if($full_coupon->discount_type == "smart_coupon"){
$emails = $full_coupon->get_email_restrictions();
if (in_array($current_email, $emails)) {
if($full_coupon->usage_count < $full_coupon->usage_limit){ ?>
coupon content
<?php }
}
}
}
}

Answer 1

As email restrictions are in an array (so an indexed array in the database) it is not possible to get that from a meta query in your WP_Query for many technical reasons.
Now instead you can do a custom very light and effective SQL query to get the "smart" coupons that belong to an email, using the WPDB Class.
I have embedded this SQL query in the function below (where the $discount_type argument is already set buy default to "smart_coupon"):
function get_coupons_from_email( $current_email, $discount_type = 'smart_coupon' ) {
global $wpdb;
return $wpdb->get_col( $wpdb->prepare("
SELECT p.post_name
FROM {$wpdb->prefix}posts p
INNER JOIN {$wpdb->prefix}postmeta pm
ON p.ID = pm.post_id
INNER JOIN {$wpdb->prefix}postmeta pm2
ON p.ID = pm2.post_id
WHERE p.post_type = 'shop_coupon'
AND p.post_status = 'publish'
AND pm.meta_key = 'discount_type'
AND pm.meta_value = '%s'
AND pm2.meta_key = 'customer_email'
AND pm2.meta_value LIKE '%s'
ORDER BY p.post_name DESC
", $discount_type, '%'.$current_email.'%' ) );
}
Code goes in functions.php file of the active child theme (or active theme). Tested and works.
Now you can use it in your code as follows:
// Get smart coupons from email
$smart_coupon_codes = get_coupons_from_email( $current_email );
if ( count($smart_coupon_codes) > 0 ) {
// Loop through smart coupons code
foreach ( $smart_coupon_codes as $coupon_code ) {
$coupon = new WC_Coupon( $coupon_code ); // Get the WC_Coupon Object
if( $coupon->get_usage_count() < $coupon->get_usage_limit() ){
?>
<p>coupon content</p>
<?php
}
}
}
It should work smoothly now.