Support inserting NULL values for strict DB mode (#39396)

* Support inserting NULL values for strict DB mode

* Set default date for placeholder order to support strict MySQL.

* Add unit test to verify strict mode also works.

* Make HPOS behavior of modified date consistent with WP_Post.

In HPOS we were leaving modified date to be empty, while WP_Post set it to the created date if modified date is null.

plugins/woocommerce/changelog/fix-35612

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fix
+
+Support inserting NULL values for strict DB mode for DataBase Util's insert_on_duplicate_key_update method.

plugins/woocommerce/src/Internal/DataStores/Orders/OrdersTableDataStore.php

@@ -1659,6 +1659,7 @@ FROM $order_meta_table
 					'post_type'     => $data_sync->data_sync_is_enabled() ? $order->get_type() : $data_sync::PLACEHOLDER_ORDER_POST_TYPE,
 					'post_status'   => 'draft',
 					'post_parent'   => $order->get_changes()['parent_id'] ?? $order->get_data()['parent_id'] ?? 0,
+					'post_date_gmt' => current_time( 'mysql', 1 ), // We set the date to prevent invalid date errors when using MySQL strict mode.
 				)
 			);
 
@@ -2287,6 +2288,10 @@ FROM $order_meta_table
 			$order->set_date_created( time() );
 		}
 
+		if ( ! $order->get_date_modified( 'edit' ) ) {
+			$order->set_date_modified( current_time( 'mysql' ) );
+		}
+
 		$this->update_order_meta( $order );
 
 		$this->persist_order_to_db( $order, $force_all_fields );
@@ -2370,7 +2375,7 @@ FROM $order_meta_table
 		$changes = $order->get_changes();
 
 		if ( ! isset( $changes['date_modified'] ) ) {
-			$order->set_date_modified( time() );
+			$order->set_date_modified( current_time( 'mysql' ) );
 		}
 
 		$this->persist_order_to_db( $order );

plugins/woocommerce/src/Internal/Utilities/DatabaseUtil.php

@@ -233,19 +233,35 @@ class DatabaseUtil {
 	 */
 	public function insert_on_duplicate_key_update( $table_name, $data, $format ) : int {
 		global $wpdb;
+		if ( empty( $data ) ) {
+			return 0;
+		}
 
 		$columns      = array_keys( $data );
+		$value_format = array();
+		$values       = array();
+		$index        = 0;
+		// Directly use NULL for placeholder if the value is NULL, since otherwise $wpdb->prepare will convert it to empty string.
+		foreach ( $data as $key => $value ) {
+			if ( is_null( $value ) ) {
+				$value_format[] = 'NULL';
+			} else {
+				$values[]       = $value;
+				$value_format[] = $format[ $index ];
+			}
+			$index++;
+		}
 		$column_clause       = '`' . implode( '`, `', $columns ) . '`';
-		$value_placeholders  = implode( ', ', array_values( $format ) );
+		$value_format_clause = implode( ', ', $value_format );
 		$on_duplicate_clause = $this->generate_on_duplicate_statement_clause( $columns );
 		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare -- Values are escaped in $wpdb->prepare.
 		$sql = $wpdb->prepare(
 			"
 INSERT INTO $table_name ( $column_clause )
-VALUES ( $value_placeholders )
+VALUES ( $value_format_clause )
 $on_duplicate_clause
 ",
-			array_values( $data )
+			$values
 		);
 		// phpcs:enable
 		// phpcs:ignore WordPress.DB.PreparedSQL.NotPrepared -- $sql is prepared.

plugins/woocommerce/tests/php/src/Internal/DataStores/Orders/OrdersTableDataStoreTests.php

@@ -68,6 +68,7 @@ class OrdersTableDataStoreTests extends HposTestCase {
 	 * Destroys system under test.
 	 */
 	public function tearDown(): void {
+		global $wpdb;
 		//phpcs:ignore WordPress.DateTime.RestrictedFunctions.timezone_change_date_default_timezone_set -- We need to change the timezone to test the date sync fields.
 		update_option( 'timezone_string', $this->original_time_zone );
 		$this->toggle_cot_feature_and_usage( $this->cot_state );
@@ -1996,6 +1997,37 @@ class OrdersTableDataStoreTests extends HposTestCase {
 		$this->assertEquals( $modified_date->format( 'Y-m-d H:i:s' ), $post->post_modified_gmt );
 	}
 
+	/**
+	 * @testDox Test that inserting with strict SQL mode is also supported.
+	 */
+	public function test_order_create_with_strict_mode_and_null_values() {
+		global $wpdb;
+		$this->toggle_cot_feature_and_usage( true );
+		$sql_mode = $wpdb->get_var( 'SELECT @@sql_mode' );
+		// Set SQL mode to strict to disallow 0 dates.
+		$wpdb->query( "SET sql_mode = 'TRADITIONAL'" );
+
+		$order = new WC_Order();
+		$this->switch_data_store( $order, $this->sut );
+		$order->save();
+
+		$this->assertTrue( $order->get_id() > 0 );
+
+		// Let's also repeat with sync off.
+		$this->enable_cot_sync();
+		$order = new WC_Order();
+		$this->switch_data_store( $order, $this->sut );
+		$order->save();
+
+		$this->assertTrue( $order->get_id() > 0 );
+		$order = wc_get_order( $order->get_id() );
+		$post  = get_post( $order->get_id() );
+		$this->assertEquals( $order->get_date_modified()->format( 'Y-m-d H:i:s' ), $post->post_date );
+
+		// phpcs:ignore -- Hardcoded value.
+		$wpdb->query( "SET sql_mode = '$sql_mode' " );
+	}
+
 	/**
 	 * @testDox Test that multiple calls to read don't try to sync again.
 	 */