subscribe query and publish - how?

[pw44]

I'm trying the following:

subscribe to a topic by paylod make a query to a database publish to another topic.

` mqtt = new Bluerhinos\phpMQTT($server, $port, $client_id); if(!$mqtt->connect(true, NULL, $username, $password)) { echo "Failed to connect to Mqtt: "; exit(1); }

$con = new mysqli($mysql_host, $mysql_user, $mysql_pass, $mysql_mydb ); if ($con -> connect_errno) { echo "Failed to connect to MySQL: " . $con -> connect_error; exit(2); } $con->set_charset('utf8mb4'); // always set the charset

$mqtt->debug = true;

$topics['rfid/card/ping'] = array('qos' => 0, 'function' => 'procMsg'); $mqtt->subscribe($topics, 0); while($mqtt->proc()) { // echo "proc....."; } $mqtt->close();

function procMsg($topic, $msg){ echo 'Msg Recieved: ' . date('r') . "\n"; echo "Topic: {$topic}\n"; echo "Payload: {$msg}\n"; echo $msg; echo "\n"; // query con //$tagid = "39EAB06D"; $query = "SELECT name, id FROM rfidtags WHERE id = ?"; $stmt = $con->prepare($query); $stmt->bind_param('s', $msg); $stmt->execute(); $stmt->store_result(); $stmt->bind_result($name, $id); if ($stmt->fetch()) { echo "$name $id\n"; echo "1"; } else { echo "failed to fetch data\n"; echo "2"; } $con->close(); } `

but the error:

paulo@hp15pw:~/TOOLS/MQTT-PHP$ php subscribe-query-publish.php Mon, 19 Jul 2021 12:22:32 -0300: Received CMD: 3 (PUBLISH) Mon, 19 Jul 2021 12:22:32 -0300: Fetching: 24 bytes Msg Recieved: Mon, 19 Jul 2021 12:22:32 -0300 Topic: rfid/card/ping Payload: 39EAB06D 39EAB06D PHP Notice: Undefined variable: con in /home/paulo/TOOLS/MQTT- PHP/subscribe-query-publish.php on line 51 PHP Fatal error: Uncaught Error: Call to a member function prepare() on null in /home/paulo/TOOLS/MQTT-PHP/subscribe-query-publish.php:51 Stack trace:

0 [internal function]: procMsg()

1 /home/paulo/TOOLS/MQTT-PHP/phpMQTT.php(482): call_user_func()

2 /home/paulo/TOOLS/MQTT-PHP/phpMQTT.php(547): Bluerhinos\phpMQTT-

message()

3 /home/paulo/TOOLS/MQTT-PHP/subscribe-query-publish.php(36):

Bluerhinos\phpMQTT->proc()

4 {main}

thrown in /home/paulo/TOOLS/MQTT-PHP/subscribe-query-publish.php on line 51

any clue?

[anhlephuoc]

The $con variable you used in the procMsg() function is a local version because it is undeclared. An uninitialised $con is used. If you want to refer to the GLOBAL version of the $con you initialised earlier, then you should declare as such in the function procMsg().

[pw44]

hi, thx for answering.

solved it in a much easier way:

`
<?php

 require('phpMQTT.php');

 $server = 'hp15pw';     // change if necessary
 $port = 1883;                     // change if necessary
 $username = 'mqttuser';                   // set your username
 $password = 'mqttpass';                   // set your password
 $client_id = 'phpMQTTDB'; // make sure this is unique for connecting to sever - you could use uniqid()

 $mysql_host = 'localhost';
 $mysql_port = '';
 $mysql_user = 'dbuser';
 $mysql_pass = 'dbpass';
 $mysql_mydb = 'rfidcards';

 $mqtt = new Bluerhinos\phpMQTT($server, $port, $client_id);
 if(!$mqtt->connect(true, NULL, $username, $password)) {
   echo "Failed to connect to Mqtt: ";
   exit(1);
 }

 $con = new mysqli($mysql_host, $mysql_user, $mysql_pass, $mysql_mydb );
 if ($con -> connect_errno) {
     echo "Failed to connect to MySQL: " . $con -> connect_error;
     exit(2);
  }
 $con->set_charset('utf8mb4'); // always set the charset

 //$mqtt->debug = true;

 while (true) {

       $msg = $mqtt->subscribeAndWaitForMessage('rfid/card/ping', 0);
       echo "$msg";

       // query con
       //$tagid = "39EAB06D";
       $query = "SELECT name, id  FROM rfidtags WHERE id = ?";
       $stmt = $con->prepare($query);
       $stmt->bind_param('s', $msg);
       $stmt->execute();
       $stmt->store_result();
       $stmt->bind_result($name, $id);
       if ($stmt->fetch()) {
            echo "$name $id\n";
           $pong="1";
       } else {
           echo "failed to fetch data\n";
           $pong= "2";
       }
       $mqtt->publish('rfid/card/pong', "$pong", 0, false);

   }

  $con->close(); 
  $mqtt->close();

`

[anhlephuoc]

The problem here is with your own basic PHP coding. Nothing to do phpMQTT code. You have received a suggestion for fixing you program; and you also have your own fix. May be it's time to close the issue!. No body else can fix your own code for you.