Retrieve XML from HTTP POST request using php

Question

I have checked similar questions but none solves the problem I'm facing.

I'm building a web service and I want to retrieve the XML data from a HTTP POST request, manipulate the data and return a response. The information below ought to be considered while writing the script:

 The communication mode is HTTP POST (not SOAP) 
 The content type is text/xml. 
 The POST request will contain only XML
 The request will be a RAW POST directly to stream and NOT in a parameter.

I've tried but my script isn't capturing the data from the HTTP POST request.

my script:

  $postData = file_get_contents('php://input');

  if(!empty($xml->MerchantReference)){
     $merchRef = (string)$xml->MerchantReference;
     $custRef = (int)$xml->CustReference;
     $username = (string)$xml->ServiceUsername;
     $password = (string)$xml->ServicePassword;
     $db->setQuery(Check if customer exists in database);
     if($db->countResultset() == 0)
     {
        header("Content-type: text/xml");
        echo "<?xml version='1.0' encoding='UTF-8'?>";
        echo "<CustomerInformationResponse>";
            echo "<MerchantReference>".$merchRef."</MerchantReference>";
            echo "<Customers>";
                echo "<Customer>";
                    echo "<Status>0</Status>";
                    echo "<CustReference>".$custRef."</CustReference>";
                    echo "<FirstName/>";
                    echo "<LastName/>";
                    echo "<OtherName/>";
                    echo "<Email/>";
                    echo "<Phone/>";
                    echo "<ThirdPartyCode/>";
                    echo "<StatusMessage>Customer is valid</StatusMessage>";
                echo "</Customer>";
            echo "</Customers>";
        echo "</CustomerInformationResponse>";
        exit;
     }

This is the HTTP POST request:

  <CustomerInformationRequest xmlns:ns2="http://test.url.com/" xmlns:ns3="http://www.w3.org/2003/05/soap-envelope">
     <ServiceUrl>MY URL</ServiceUrl>
     <ServiceUsername>12345</ServiceUsername>
     <ServicePassword>abcdef</ServicePassword>
     <RouteId>HTTPGENERICv31</RouteId>
     <Service>bill</Service>
     <MerchantReference>123456</MerchantReference>
     <CustReference>abcdef</CustReference>
     <PaymentItemCategoryCode/>
     <RequestReference/>
     <TerminalId/>
     <Amount>0</Amount>
     <FtpUsername/>
     <FtpPassword/>
 </CustomerInformationRequest>

After retrieving and manipulating the data, my script out to return a response. This is how the response should be:

     <CustomerInformationResponse>
        <MerchantReference>3527</MerchantReference >
           <Customers>
              <Customer>
                 <Status>0</Status>                    
                 <CustReference>4565</CustReference>
                 <FirstName></FirstName>                                           
                 <LastName></LastName>
                 <OtherName></OtherName>
                 <Email></Email>
                 <Phone></Phone>
                 <ThirdPartyCode/>                                                    
                 <StatusMessage>Customer is Valid</StatusMessage>
               </Customer>
             </Customers>
           </CustomerInformationResponse>

Answer 1

$merchRef = (string)$xml->MerchantReference;
//This did not work for me. However check how I formatted the code to get the xml nodes correctly

<?php
$postData = file_get_contents('php://input');
$xml=simplexml_load_string($postData);
////////////////
$merchRef=$xml->Customers[0]->Customer[0]->MerchantReference;
$custRef=$xml->Customers[0]->Customer[0]->CustReference;
?>

Answer 2

After much research, I've found the answer to my question. I discovered that after getting the data from the HTTP Post request, I didn't store it as an xml data.

So adding this line of code

 $xml = simplexml_load_string($postData);

after this

 $postData = file_get_contents('php://input');

solved it. I thought I should share it because it might be useful to someone.