How to improve the following code in PHP - php

Question

Here is a simple form I am using to send XML data in admin_xml.php
<form name="review" action="admin_xml.php" method="post">
<textarea name="xml" cols="40" rows="10"></textarea>
<input class="submit" type="submit" value="Submit Request">
</form>
Here is the XML which I enter in order to retrieve the data from MySQL Database
<?xml version="1.0" encoding="UTF-8"?>
<GetOrdersIds>
<Credentials>
<Username>my_username</Username>
<Password>my_password</Password>
</Credentials>
<Criterions>
<OrderNumber></OrderNumber>
<StartDate>2009-01-01</StartDate>
<EndDate>2009-07-01</EndDate>
</Criterions>
</GetOrdersIds>
Here is the php code which extracts the tags from the xml:
<?php
$text_all = "<?xml version=\"1.0\"?>\r\n<GetOrdersIds version=\"1.0\">\r\n<Credentials>\r\n<Username>my_username</Username>\r\n<Password>my_password</Password>\r\n</Credentials>\r\n<Criterions>\r\n<OrderNumber></OrderNumber>\r\n<StartDate>2009-01-01</StartDate>\r\n<EndDate>2009-07-01</EndDate>\r\n</Criterions>\r\n</GetOrdersIds>";
$field = "Criterions";
$result = substr($text_all, strpos($text_all, "<".$field.">")+strlen("<".$field.">"), strpos($text_all, "</".$field.">")-strlen("<".$field.">")-strpos($text_all, "<".$field.">"));
?>
The result from the above php code is:
<OrderNumber></OrderNumber>
<StartDate>2009-01-01</StartDate>
<EndDate>2009-07-01</EndDate>
When the script is run, the php code goes through my mysql data, and extracts all orders between the Start Date and the End Date given above.
Is there a better way of improving the following php code, so that it performs the same function:
$result = substr($text_all, strpos($text_all, "<".$field.">")+strlen("<".$field.">"), strpos($text_all, "</".$field.">")-strlen("<".$field.">")-strpos($text_all, "<".$field.">"));
This is the code which searches through the xml data and retrieves all the tags.
UPDATE :
Can anyone list the $result code in SimpleXML?

Answer 1

Some temp vars will help and also make it easier to read.
$result = substr($text_all, strpos($text_all, "<".$field.">")+strlen("<".$field.">"), strpos($text_all, "</".$field.">")-strlen("<".$field.">")-strpos($text_all, "<".$field.">"));
Can be rewritten to.
$tagLen = strlen('<'.$field.'>');
$openTag = strpos($text_all, '<'.$field.'>');
$closeTag = strpos($text_all, '</'.$field.'>', $openTag);
$result = substr($text_all, $openTag + $tagLen, $closeTag - $tagLen - $openTag);
or use SimpleXML
$doc = simplexml_load_string($text_all);
echo $doc->Criterions->asXML();
If you want the individual values use this.
$doc = simplexml_load_string($text_all);
echo $doc->Criterions->OrderNumber;
echo $doc->Criterions->StartDate;
echo $doc->Criterions->EndDate;
if you want the element in XML then use asXML():
$doc = simplexml_load_string($text_all);
echo $doc->Criterions->OrderNumber->asXML();
echo $doc->Criterions->StartDate->asXML();
echo $doc->Criterions->EndDate->asXML();

Answer 2

With SimpleXML:
<?php
$xmlSTR = '<?xml version="1.0" encoding="UTF-8"?>
<GetOrdersIds>
<Credentials>
<Username>my_username</Username>
<Password>my_password</Password>
</Credentials>
<Criterions>
<OrderNumber></OrderNumber>
<StartDate>2009-01-01</StartDate>
<EndDate>2009-07-01</EndDate>
</Criterions>
</GetOrdersIds>';
$xml = new SimpleXMLElement($xmlSTR);
echo $xml->Credentials->Username;
//To see the entire structure print_r($xml); as php can access objects as arrays

Answer 3

Have a look at the simplexml module.

Answer 4

Use an XML parser like SimpleXML to extract that data:
$doc = simplexml_load_string($_POST['xml']);
$OrderNumber = $doc->Criterions->OrderNumber;
$StartDate = $doc->Criterions->StartDate;
$EndDate = $doc->Criterions->EndDate;

Answer 5

Assuming your XML string is stored in the variable called $text_all (as you show in your example), this will get you what you want man... :-)
$mysql_stuff = '';
$xml = new SimpleXMLElement($text_all);
foreach($xml->Criterions->children() as $criterion) {
$mysql_stuff .= $criterion->asXML()."\n";
}
echo $mysql_stuff;
$mysql_stuff will now contain:
<OrderNumber/>
<StartDate>2009-01-01</StartDate>
<EndDate>2009-07-01</EndDate>
I tested this and it works. I hope this answers your question!