Question

I have a little script here which uses DOMDocument to get my data from my mysql database and put it in a structured XML which is later on used to be read from.

I am having a little trouble adjusting my php code to create the right structure of my XML.

Right now my code looks like this:

Code:

<markers>
<DEVS DEVICE="DEV10">
<marker USER="PRIVET_!" DATA1="0578" DATA2="0A57" TIME="18:16:40" />
</DEVS>
<DEVS DEVICE="DEV10">
<marker USER="PRIVET_!" DATA1="0578" DATA2="0A55" TIME="18:16:05" />
</DEVS>
<DEVS DEVICE="DEV5">
<marker USER="PRIVET_!" DATA1="0578" DATA2="0A55" TIME="18:16:05" />
</DEVS>
<DEVS DEVICE="DEV5">
<marker USER="PRIVET_!" DATA1="0578" DATA2="0A55" TIME="18:16:05" />
</DEVS>
</markers>

And I would like to have my code look like this:

Code:

<markers>
<DEVS DEVICE="DEV10">
<marker USER="PRIVET_!" DATA1="0578" DATA2="0A57" TIME="18:16:40" />
<marker USER="PRIVET_!" DATA1="0578" DATA2="0A55" TIME="18:16:05" />
</DEVS>
<DEVS DEVICE="DEV5">
<marker USER="PRIVET_!" DATA1="0578" DATA2="0A55" TIME="18:16:05" />
<marker USER="PRIVET_!" DATA1="0578" DATA2="0A55" TIME="18:16:05" />
</DEVS>
</markers>

And here is the PHP code I have at the moment:

PHP Code:

<?php   

require("config.php");  

// Start XML file, create parent node 

$dom = new DOMDocument("1.0"); 
$node = $dom->createElement("markers"); 
$parnode = $dom->appendChild($node);  

// Opens a connection to a MySQL server 

$connection=mysql_connect ($server, $db_user, $db_pass); 
if (!$connection) {  die('Not connected : ' . mysql_error());}  

// Set the active MySQL database 

$db_selected = mysql_select_db($database, $connection); 
if (!$db_selected) { 
  die ('Can\'t use db : ' . mysql_error()); 
}  

// Select all the rows in the markers table 

$query = "SELECT * FROM input WHERE (DEVS = 'DEV5' or DEVS = 'DEV10')  ORDER BY TIME DESC"; 
$result = mysql_query($query); 
if (!$result) {   
  die('Invalid query: ' . mysql_error()); 
}  

header("Content-type: text/xml");  

// Iterate through the rows, adding XML nodes for each 

while ($row = @mysql_fetch_assoc($result)){   
  // ADD TO XML DOCUMENT NODE   
  $node1 = $dom->createElement("DEVS"); 
  $parnode->appendChild($node1); 
  $marker = $dom->createElement("marker"); 
  $node1->appendChild($marker); 

  $marker->setAttribute("USER", $row['USER']); 
  $marker->setAttribute("DATA1", $row['DATA1']);   
  $marker->setAttribute("DATA2", $row['DATA2']);   
  $marker->setAttribute("TIME", $row['TIME']);  
  $node1->setAttribute("DEVICE", $row['DEVS']); 

} 

echo $dom->saveXML(); 

?>

I need the code to have one unique tag (DEVICE) which will be used later on as a pointer to what should be read from this XML file.
I am using DOMDocument since this is the function I am most familiar with.

Any ideas would be highly appreciated.

Thanks in advance!

Answer 1

You should make an array of nodes, and check if the node exists instead of creating it each time. To do so:

[...]
$nodes = array();

while ($row = @mysql_fetch_assoc($result)){

    // ADD TO XML DOCUMENT NODE
    $node_key = $row['DEVS'];
    if( !array_key_exists( $node_key, $nodes ) )
    {
        $nodes[$node_key] = $dom->createElement("DEVS"); 
        $parnode->appendChild($nodes[$node_key]);
        $nodes[$node_key]->setAttribute("DEVICE", $row['DEVS']);
    }
    $marker = $dom->createElement("marker"); 
    $nodes[$node_key]->appendChild($marker); 

    $marker->setAttribute("USER", $row['USER']); 
    $marker->setAttribute("DATA1", $row['DATA1']);   
    $marker->setAttribute("DATA2", $row['DATA2']);   
    $marker->setAttribute("TIME", $row['TIME']);
}

This way, what we’re doing is:

• Get the node key.
• If the node for that key isn’t created, we create it, adding it to the DOM and setting it’s attribute.
• At this point, we know for sure that the node is created, so we simply append the new element to the node.