How to process incoming JSON data from connected IoT device - mysql

Question

I need some support with a personal project Im working on. I have a connected device which sends JSON data at a defined interval (every 1 min / 5 min/ 15 mins etc) to a specific IP address on port 8080.
The JSON that is sent is in following format:
{
"MeterSN": “1234”,
"Status": ###,
“Variable1”: “###”,
"Variable2”: “###”,
"Variable3”: ###
}
I have started building a PHP Rest API to process this data but am somehow not able to save the to mySQL.
Here is what I have so far:
meterdata.php
class MeterDataInput{
private $conn;
private $table_name = "meterdata";
public $MeterSN;
public $StatusA;
public $Variable1;
public $Variable2;
public $Variable3;
public function __construct($db){
$this->conn = $db;
}
}
function createMeterRecord(){
$query = "INSERT INTO
" . $this->table_name . "
SET
MeterSN=:MeterSN, Status=:Status, Variable1=:Variable1, Variable2=:Variable2, Variable3=:Variable3";
// prepare query
$stmt = $this->conn->prepare($query);
// sanitize
$this->MeterSN=htmlspecialchars(strip_tags($this->MeterSN));
$this->Status=htmlspecialchars(strip_tags($this->Status));
$this->Variable1=htmlspecialchars(strip_tags($this->Variable1));
$this->Variable2=htmlspecialchars(strip_tags($this->Variable2));
$this->Variable3=htmlspecialchars(strip_tags($this->Variable3));
// bind values
$stmt->bindParam(":MeterSN", $this->MeterSN);
$stmt->bindParam(":Status", $this->Status);
$stmt->bindParam(":Variable1", $this->Variable1);
$stmt->bindParam(":Variable2", $this->Variable2);
$stmt->bindParam(":Variable3", $this->Variable3);
// execute query
if($stmt->execute()){
return true;
}
return false;
}
index.php
// required headers
header("Access-Control-Allow-Origin: *");
header("Content-Type: application/json; charset=UTF-8");
header("Access-Control-Allow-Methods: POST");
header("Access-Control-Max-Age: 3600");
header("Access-Control-Allow-Headers: Content-Type, Access-Control-Allow-Headers, Authorization, X-Requested-With");
// get database connection
include_once 'config/db.php';
// instantiate MeterData object
include_once 'objects/meterdata.php';
$database = new Database();
$db = $database->getConnection();
$meterdata = new MeterDataInput($db);
// get posted data
$data = json_decode(file_get_contents("php://input"));
// make sure data is not empty
if(!empty($data->MeterSN)){
// set product property values
$meterdata->MeterSN = $data->MeterSN;
$meterdata->Status = $data->Status;
$meterdata->Variable1 = $data->Variable1;
$meterdata->Variable2 = $data->Variable2;
$meterdata->Variable3 = $data->Variable3;
// create the meter data entry
if($meterdata->createMeterRecord()){
// set response code - 201 created
http_response_code(201);
// update the status
echo json_encode(array("message" => "Data record was added"));
}
// if unable to create the record
else{
// set response code - 503 service unavailable
http_response_code(503);
// tell the user
echo json_encode(array("message" => "Unable to add record."));
}
}
// data is incomplete
else{
// set response code - 400 bad request
http_response_code(400);
// tell the user
echo json_encode(array("message" => "Unable to create data record. Data is incomplete."));
}
Obviously i also have config.php and db.php
I am not sure where i am going wrong, however I am not able to see the records popupate within mySQL.