Improve the way we do queries (#22043)

* Improve the way we do queries

* PHP legacy compatible

* Update aproach to filter queries with empty values

* Fixing Unit Tests

* Moving Unit Test to its the correct test function

* Filter missing the new param, allow_empty, also simplifiying unit test.

* Helper function to create counpon does not support empty coupon codes

* Helper function does not need to allot empty search

* Wrong code standard

* Fixing Code Standard Unit Test

includes/wc-coupon-functions.php

@@ -17,7 +17,8 @@ defined( 'ABSPATH' ) || exit;
  */
 function wc_get_coupon_types() {
 	return (array) apply_filters(
-		'woocommerce_coupon_discount_types', array(
+		'woocommerce_coupon_discount_types',
+		array(
 			'percent'       => __( 'Percentage discount', 'woocommerce' ),
 			'fixed_cart'    => __( 'Fixed cart discount', 'woocommerce' ),
 			'fixed_product' => __( 'Fixed product discount', 'woocommerce' ),
@@ -77,7 +78,7 @@ function wc_coupons_enabled() {
  */
 function wc_get_coupon_code_by_id( $id ) {
 	$data_store = WC_Data_Store::load( 'coupon' );
-	return (string) $data_store->get_code_by_id( $id );
+	return empty( $id ) ? '' : (string) $data_store->get_code_by_id( $id );
 }
 
 /**
@@ -89,6 +90,11 @@ function wc_get_coupon_code_by_id( $id ) {
  * @return int
  */
 function wc_get_coupon_id_by_code( $code, $exclude = 0 ) {
+
+	if ( empty( $code ) ) {
+		return 0;
+	}
+
 	$data_store = WC_Data_Store::load( 'coupon' );
 	$ids        = wp_cache_get( WC_Cache_Helper::get_cache_prefix( 'coupons' ) . 'coupon_id_from_code_' . $code, 'coupons' );
 

tests/unit-tests/coupon/functions.php

@@ -1,5 +1,4 @@
 <?php
-
 /**
  * Class Functions.
  * @package WooCommerce\Tests\Coupon
@@ -76,6 +75,9 @@ class WC_Tests_Functions extends WC_Unit_Test_Case {
 		// Delete coupon.
 		WC_Helper_Coupon::delete_coupon( $coupon->get_id() );
 
+		$this->assertEquals( 0, wc_get_coupon_id_by_code( '' ) );
+
 		$this->assertEmpty( wc_get_coupon_id_by_code( 0 ) );
 	}
+
 }