How to delete xml Dom document in php - php

Question

I'd search for this problem and find some questions but they didn't mention to my error...
I'm trying to remove a child of my DOM document and when I type the $x->removeChild($key); function, nothing happend...
$xmlreq = new DOMDocument;
$xmlreq->loadXML($xmlStr);
$x = $xmlreq->getElementsByTagName('*');
foreach($x as $key)
{
if (substr($key->nodeValue,0,3)=="{{{" and substr($key->nodeValue,-3)=="}}}")
{
$field = explode("|",substr($key->nodeValue,3,strlen($key->nodeValue)-6));
if((int)$field[3]==0)
{
if(trim($_POST[$field[2]])=="")
{
$x->removeChild($key);
}else{
$key->nodeValue = trim($_POST[$field[2]]);
}
}elseif((int)$field[3]==1)
{
if(trim($_POST[$field[2]])=="")
{
$errors.="";
}else{
$key->nodeValue = trim($_POST[$field[2]]);
}
}else{
}
}
}
header("content-type: application/xml");
print $xmlreq->saveXml();
and this is my xml:
<epp xmlns="urn:ietf:params:xml:ns:epp-1.0">
<command>
<check>
<contact:check xmlns:contact="http://epp.nic.ir/ns/contact-1.0">
<contact:id>ghhg-ghgh</contact:id>
<contact:id>45</contact:id>
<contact:id>45</contact:id>
<contact:id>45</contact:id>
<contact:authInfo>
<contact:pw>1561651321321</contact:pw>
</contact:authInfo>
</contact:check>
</check>
<clTRID>TEST-12345</clTRID>
</command>
</epp>
and I want to delete one of <contact:id>45</contact:id>

Answer 1

Your loop does nothing since the outer conditional is looking for a node where nodeValue starts with {{{ and ends with }}}:
foreach($x as $key)
{
if (substr($key->nodeValue,0,3)=="{{{" and substr($key->nodeValue,-3)=="}}}")
Additionally, there's no removeChild() method in DOMNodeList. You probably want to fetch the node's parent first and call its removeChild() method instead.
A possible alternative:
$x = $xmlreq->getElementsByTagName('*');
$remove = TRUE;
foreach($x as $key)
{
if( $key->nodeName=='contact:id' && $key->nodeValue=='45' ){
if($remove){
$key->parentNode->removeChild($key);
$remove = FALSE;
}
}
}