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Remove XML parent node based on value of child node with php domdocument

Posted on 2014-09-03
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Last Modified: 2014-09-04
I've tried everything I could find and think of to get this working correctly, to no avail.  I'm trying to delete an xml node based on the node value of one of it's children (entrynum).  Again, I've tried several different approaches and variations of them with no success.  The logic seems correct, but I've been getting inexplicable output with no errors.  I've gotten close, but still with erratic, unpredictable behavior.  Here's where I'm at with it now (my latest attempt anyway).  Any suggestions.  Thanks in advance.

The XML in entries.xml:

<?xml version="1.0" encoding="utf-8"?>
<entries>
  <entry>
    <title>0</title>
    <entrydate>0</entrydate>
    <contents>0</contents>
    <entrynum>0</entrynum>
  </entry>
  <entry>
    <title>1</title>
    <entrydate>1</entrydate>
    <contents>1</contents>
    <entrynum>1</entrynum>
  </entry>
  <entry>
    <title>2</title>
    <entrydate>2</entrydate>
    <contents>2</contents>
    <entrynum>2</entrynum>
  </entry>
  <entry>
    <title>3</title>
    <entrydate>3</entrydate>
    <contents>3</contents>
    <entrynum>3</entrynum>
  </entry>
</entries>

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And here's the php: (if entrynum = $GLOBALS[num] I want that node removed when the script runs).

$entries = new DOMDocument('1.0', 'utf-8');
	$entries->formatOutput = true;
	$entries->preserveWhiteSpace = true;
	$entries->load('entries.xml');

	$entry_node = $entries->getElementsByTagName("entries")->item(0);
	
	
	foreach($entry_node->getElementsByTagName("entry") as $node){
	if($node->getElementsByTagName("entrynum")->nodeValue = $GLOBALS['num']){
	$node->parentNode->removeChild($node);}}
		
		
	$entries->save('entries.xml');

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0
Comment
Question by:Kaiser
  • 4
  • 4
8 Comments
 
LVL 110

Expert Comment

by:Ray Paseur
ID: 40303416
Please see: http://iconoun.com/demo/temp_kwkened.php
<?php // demo/temp_kwkened.php
error_reporting(E_ALL);

// SEE http://www.experts-exchange.com/Web_Development/WebApplications/Q_28511238.html

// TEST DATA
$xml = <<<EOD
<?xml version="1.0" encoding="utf-8"?>
<entries>
  <entry>
    <title>0</title>
    <entrydate>0</entrydate>
    <contents>0</contents>
    <entrynum>0</entrynum>
  </entry>
  <entry>
    <title>1</title>
    <entrydate>1</entrydate>
    <contents>1</contents>
    <entrynum>1</entrynum>
  </entry>
  <entry>
    <title>2</title>
    <entrydate>2</entrydate>
    <contents>2</contents>
    <entrynum>2</entrynum>
  </entry>
  <entry>
    <title>3</title>
    <entrydate>3</entrydate>
    <contents>3</contents>
    <entrynum>3</entrynum>
  </entry>
</entries>
EOD;

// DELETION SIGNAL (if entrynum = $GLOBALS[num]
$GLOBALS['num'] = 2;

// MAKE AN OBJECT
$obj = SimpleXML_Load_String($xml);

// REMOVE THE NODE
unset($obj->entry[$GLOBALS['num']]);

// RECOVER THE XML AND SHOW THE WORK PRODUCT
$new = $obj->AsXML();
echo '<pre>' . htmlentities($new);

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0
 

Author Comment

by:Kaiser
ID: 40303586
Hi Ray,

Thank you for the response.  To be sure I understand, when removing the node with
unset($obj->entry[$GLOBALS['num']]);

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 won't this remove the node based on its position in the xml tree?  What I'd like to do is remove a child node (entrynum) of the entry node.  So something like this:  
$obj->entry->entrynum

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to target the child node.  But to delete that child node based on its value rather than its position, how should I target its value?
0
 
LVL 110

Expert Comment

by:Ray Paseur
ID: 40303645
Ahh, I get it - coincidental alignment.  Let me get another code sample for you.
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Author Comment

by:Kaiser
ID: 40303658
Ray,

I need to be able to remove the entry node based on the value of entrynum, so that when entry nodes are removed I can still remove the desired node based on the value of entrynum, because every time a node is removed, the remaining nodes below it move up a position, so targeting their position in the xml tree won't work.  Hope I'm explaining that clearly.  Thanks again.

<entries>
  <entry>
    <title>0</title>
    <entrydate>0</entrydate>
    <contents>0</contents>
    <entrynum>0</entrynum>
  </entry>
  <entry>
    <title>2</title>
    <entrydate>2</entrydate>
    <contents>2</contents>
    <entrynum>2</entrynum>
  </entry>
  <entry>
    <title>6</title>
    <entrydate>6</entrydate>
    <contents>6</contents>
    <entrynum>6</entrynum>
  </entry>
  <entry>
    <title>3</title>
    <entrydate>3</entrydate>
    <contents>3</contents>
    <entrynum>3</entrynum>
  </entry>
</entries>

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0
 

Author Comment

by:Kaiser
ID: 40303667
Yes exactly, coincidental alignment.  I should have presented it more clearly.
0
 
LVL 110

Accepted Solution

by:
Ray Paseur earned 500 total points
ID: 40303700
Try this.  Note the use of "foo" in the script.

<?php // demo/temp_kwkened.php
error_reporting(E_ALL);

// SEE http://www.experts-exchange.com/Web_Development/WebApplications/Q_28511238.html

// TEST DATA
$xml = <<<EOD
<?xml version="1.0" encoding="utf-8"?>
<entries>
  <entry>
    <title>0</title>
    <entrydate>0</entrydate>
    <contents>0</contents>
    <entrynum>0</entrynum>
  </entry>
  <entry>
    <title>1</title>
    <entrydate>1</entrydate>
    <contents>1</contents>
    <entrynum>1</entrynum>
  </entry>
  <entry>
    <title>2</title>
    <entrydate>2</entrydate>
    <contents>2</contents>
    <entrynum>foo</entrynum>
  </entry>
  <entry>
    <title>3</title>
    <entrydate>3</entrydate>
    <contents>3</contents>
    <entrynum>bar</entrynum>
  </entry>
</entries>
EOD;

// DELETION SIGNAL (if entrynum = $GLOBALS[num]
$GLOBALS['num'] = 'foo';

// MAKE AN OBJECT
$obj = SimpleXML_Load_String($xml);

// USE A COUNTING ITERATOR TO FIND THE ELEMENT WE WANT TO DELETE
$cnt = 0;
foreach ($obj as $ent)
{
    if ($ent->entrynum == $GLOBALS['num'])
    {
        unset($obj->entry[$cnt]);
    }
    $cnt++;
}

// RECOVER THE XML AND SHOW THE WORK PRODUCT
$new = $obj->AsXML();
echo '<pre>' . htmlentities($new);

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0
 

Author Comment

by:Kaiser
ID: 40303759
Wow!  Simply awesome.  I tried using a counter like that to cycle through the nodes and test the condition, but with a while loop.  This is great, thank you!
0
 
LVL 110

Expert Comment

by:Ray Paseur
ID: 40304358
Thanks for the points - it's a great question, ~Ray
0

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