Remove address indexes from list of internal keys. (#35192)

* Override filter_meta_data method, since it should be a no-op anyway.

* Add changelog.

* Not include address indexes from filtered data.

* Applied coding standards.

plugins/woocommerce/changelog/fix-duplicate_meta

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fix
+
+Override filter_meta_data method, since it should be a no-op anyway.

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

@@ -1031,6 +1031,35 @@ WHERE
 		$order->set_object_read( true );
 	}
 
+	/**
+	 * For post based data stores, this was used to filter internal meta data. For custom tables, technically there is no internal meta data,
+	 * (i.e. we store all core data as properties for the order, and not in meta data). So this method is a no-op.
+	 *
+	 * Except that some meta such as billing_address_index and shipping_address_index are infact stored in meta data, so we need to filter those out.
+	 *
+	 * However, declaring $internal_meta_keys is still required so that our backfill and other comparison checks works as expected.
+	 *
+	 * @param \WC_Data $object Object to filter meta data for.
+	 * @param array    $raw_meta_data Raw meta data.
+	 *
+	 * @return array Filtered meta data.
+	 */
+	public function filter_raw_meta_data( &$object, $raw_meta_data ) {
+		$filtered_meta_data = parent::filter_raw_meta_data( $object, $raw_meta_data );
+		$allowed_keys       = array(
+			'_billing_address_index',
+			'_shipping_address_index',
+		);
+		$allowed_meta       = array_filter(
+			$raw_meta_data,
+			function( $meta ) use ( $allowed_keys ) {
+				return in_array( $meta->meta_key, $allowed_keys, true );
+			}
+		);
+
+		return array_merge( $allowed_meta, $filtered_meta_data );
+	}
+
 	/**
 	 * Sync order to/from posts tables if we are able to detect difference between order and posts but the sync is enabled.
 	 *

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

@@ -1867,4 +1867,32 @@ class OrdersTableDataStoreTests extends WC_Unit_Test_Case {
 		$product->save();
 		$this->assertFalse( wc_get_order( $product->get_id() ) );
 	}
+
+	/**
+	 * @testDox Test that we are not duplicating address indexing when updating.
+	 */
+	public function test_address_index_saved_on_update() {
+		global $wpdb;
+		$this->toggle_cot( true );
+		$this->disable_cot_sync();
+		$order = new WC_Order();
+		$order->set_billing_address_1( '123 Main St' );
+		$order->save();
+
+		$this->assertTrue( false !== strpos( $order->get_meta( '_billing_address_index', true ), '123 Main St' ) );
+		$order = wc_get_order( $order->get_id() );
+		$order->set_billing_address_2( 'Apt 1' );
+		$order->save();
+
+		$order_meta_table = $this->sut::get_meta_table_name();
+		// Assert that we are not duplicating address indexes.
+		$result = $wpdb->get_var(
+			$wpdb->prepare(
+				"SELECT COUNT(*) FROM {$order_meta_table} WHERE order_id = %d AND meta_key = '_billing_address_index'", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
+				$order->get_id()
+			)
+		);
+
+		$this->assertEquals( 1, $result );
+	}
 }