Accessing data sent to callback URL - php

Question

Following a successful response from an API Request to M-PESA where the following JSON code is printed:
{ "MerchantRequestID":"2690XXXXXXX", "CheckoutRequestID":"xx_XX_2779308581984", "ResponseCode": "0", "ResponseDescription":"Success. Request accepted for processing", "CustomerMessage":"Success. Request accepted for processing" }
I would like to access the data sent to my callback url: https://xxxxxxxxxxxxxxxxx.ngrok.io/processL/transact.php . Despite expecting the code to change accordingly upon cancellation or payment, nothing happens although when I inspect the response on the ngrok local tunnel online interface, I see my expected results only that I do not know how to acquire and generate some action with them. Below is the code making the API Request and the results which I expect to be sent to my call back url but in vain.
<!-- transact.php -->
<?php
if (isset($_POST['submit'])) {
$Passkey = 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx';
$Amount= $_POST['amt'];
$BusinessShortCode = '174379';
$PartyA =$_POST['phone'];
$AccountReference =$_POST['name'];
$TransactionDesc = 'test';
$Timestamp =date('YmdHis');
$Password = base64_encode($BusinessShortCode.$Passkey.$Timestamp);
$headers=['Content-Type:application/json; charset=utf8'];
$initiate_url='https://sandbox.safaricom.co.ke/mpesa/stkpush/v1/processrequest';
$callBackURL ='https://xxxxxxxxxxxxxxxxx.ngrok.io/processL/transact.php';
function accessToken() {
$ConsumerKey = 'ubYsxxxxxxxxxxxxx';
$ConsumerSecret = 'xxxxxxxxxxxxx';
$credentials = base64_encode($ConsumerKey.":".$ConsumerSecret);
$url = "https://sandbox.safaricom.co.ke/oauth/v1/generate?grant_type=client_credentials";
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_HTTPHEADER, array("Authorization: Basic ".$credentials,"Content-Type:application/json"));
curl_setopt($curl, CURLOPT_HEADER, false);
// curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
$curl_response = curl_exec($curl);
$access_token=json_decode($curl_response);
curl_close($curl);
return $access_token->access_token;
}
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $initiate_url);
curl_setopt($curl, CURLOPT_HTTPHEADER, array('Content-Type:application/json','Authorization:Bearer '.accessToken()));
$curl_post_data = array(
'BusinessShortCode' =>$BusinessShortCode,
'Password' => $Password,
'Timestamp' => $Timestamp,
'TransactionType' => 'CustomerPayBillOnline',
'Amount' => $Amount,
'PartyA' => $PartyA,
'PartyB' => $BusinessShortCode,
'PhoneNumber' => $PartyA,
'CallBackURL' => $callBackURL,
'AccountReference' => $AccountReference,
'TransactionDesc' => $TransactionDesc
);
$data_string = json_encode($curl_post_data);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_POST, true);
curl_setopt($curl, CURLOPT_POSTFIELDS, $data_string);
$curl_response = curl_exec($curl);
print_r($curl_response."<br>");
}
Upon acceptance of payment:
{
"Body": {
"stkCallback": {
"MerchantRequestID": "xxxxxxxxxxxxx",
"CheckoutRequestID": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
"ResultCode": 0,
"ResultDesc": "The service request is processed successfully.",
"CallbackMetadata": {
"Item": [
{
"Name": "Amount",
"Value": 1
},
{
"Name": "MpesaReceiptNumber",
"Value": "xxxxxxxxxxxxx"
},
{
"Name": "Balance"
},
{
"Name": "TransactionDate",
"Value": 20210927101413
},
{
"Name": "PhoneNumber",
"Value": xxxxxxxxxxxxx
}
]
}
}
}
};
When payment is cancelled:
{
"Body": {
"stkCallback": {
"MerchantRequestID": "xxxxxxxxxxxxx",
"CheckoutRequestID": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
"ResultCode": 1032,
"ResultDesc": "Request cancelled by user"
}
}
};
I need some guidance.

Answer 1

The documentation for json_decode() is your friend. If you pass true as the second argument then it returns your JSON data as associative arrays.
$access_token=json_decode($curl_response, true);
// Check the response value
$result = $access_token['Body']['stkCallback']['ResultCode'] ?? null;
if ($result == 0) {
// Success
}