Exception array_merge(): Argument #1 must be of type array in NonBlockingClient.php:183

[niniob]

Using WriteRegistersBuilder to write registers leads to following exception:
Fatal error: Uncaught TypeError: array_merge(): Argument #1 must be of type array, ModbusTcpClient\Packet\ModbusFunction\WriteMultipleRegistersResponse given in /php/modbus-test-01/vendor/aldas/modbus-tcp-client/src/Network/NonBlockingClient.php:183

Issue seems to be line 183 in NonBlockingClient.php:
$data = array_merge(...$data);

I'm not sure why array_merge and the spread operator are used together. I assume it should be just
$data = array_merge($data);

At least this fixes the issue for me.

Example to reproduce the issue:

<?php
require __DIR__ . '/vendor/autoload.php';
use ModbusTcpClient\Composer\Write\WriteRegistersBuilder;
use ModbusTcpClient\Network\NonBlockingClient;

$request = WriteRegistersBuilder::newWriteMultipleRegisters()
				->allFromArray([['uri' => 'tcp:https://192.168.100.10:5555', 'type' => 'uint16', 'value' => 123, 'address' => 1024, 'unitId' => 1]])
				->build();

$response = (new NonBlockingClient())->sendRequests($request);
?>

Environment:

• OS: MacOS 13.3.1
• PHP version 8.1.5
• Library version 3.1.1

[aldas]

This is a bug with Write requests. Basically Composer Requests should extract values as array. Like ReadRegisterRequest does it here

modbus-tcp-client/src/Composer/Read/Register/ReadRegisterRequest.php

Line 73 in 3d6af61

public function parse(string $binaryData): array|ErrorResponse

but WriteRegisterRequest

modbus-tcp-client/src/Composer/Write/Register/WriteRegisterRequest.php

Line 70 in 3d6af61

public function parse(string $binaryData): ModbusResponse

just returns own instance instead of array - this is a bug / something that I forgot.

I will fix it.

[aldas]

I have released version 3.2.0 that contains fix for this problem.

[niniob]

Excellent, the fix works fine with PHP 8, many thanks for the quick response. But have in addition an environment still running PHP 7.4.28 which cannot be upgraded to PHP 8. Therefore I need to use version 2.4.0 of modbus-tcp-client. Any chance to get the fix also downported to 2.4.0?

[aldas]

@niniob I think you could create custom patch for PHP 7 and let composer to apply it.

See

1. https://www.howtogeek.com/devops/how-to-apply-your-own-patches-to-composer-packages/
2. https://scandiweb.com/blog/php-series-using-a-composer-patch/

[niniob]

@niniob I think you could create custom patch for PHP 7 and let composer to apply it.

Thanks, custom patch might be an option, but I found another workaround: Create NonBlockingClient with option 'flatRequestResponse' => false. This avoids $data = array_merge(...$data) being called.

$response = (new NonBlockingClient([ 'flatRequestResponse' => false ]))->sendRequests($request);

[aldas]

aa yeah, this is also an option as write requests do not need responses.