Php SimpleXML checks if a child exists

Question

A->b->c may exist, but c may not exist. How to check it?

Answer 1

 if($A->b->c != null) //c exists 

If c does not exist, its value will be null (or, more precisely, it will not matter). Note, however, that for this, both A and b need not be null . Otherwise, PHP will throw an error (I think).

Answer 2

Better wrap this in isset()

 if(isset($A->b->c)) { // c exists 

Thus, if $A or $A->b does not exist ... it will not explode.

Answer 3

SimpleXML always returns an object. If there is no child, an empty object is returned.

 if( !empty($a->b)){ var_dump($a->b); } 

Answer 4

I solved it using the children() function and ran count() on it, ignoring the PHP error if there are no children, putting @ before the call to count. This is stupid, but it works:

 $identification = $xml->identification; if (@count($identification->children()) == 0) $identification = $xml->Identification; 

I hate this...

Answer 5

Xpath method returns an array of matched elements or false

 if(false !== $A->xpath('b/c')) { ... 

http://www.php.net/manual/ru/simplexmlelement.xpath.php

Answer 6

After some experimentation, I found that the only reliable method for checking the existence of a node is using count($xml->someNode) .

Here is a test case: https://gist.github.com/Thinkscape/6262156

Answer 7

If you have PHP 5.3, you can simply use $a->count() . Otherwise, the scippie solution using @count($a->children()) works well. I believe I do not need @, but an earlier PHP implementation may be required.

Answer 8

Using if(isset($A->b){ gave me problems, so I tried if($A->b){ and it worked!

Answer 9

Using xpath:

 function has_child(\SimpleXMLElement $parent=null, string $xpathToChild) { return isset($parent) && !empty($parent->xpath('('.$xpathToChild.')[1]')); } 

where $parent is the indirect or direct parent of the child being checked, and $xpathToChild is the xpath of the child relative to $parent .

()[1] because we do not want to select all child nodes. One is enough.

To check if $ a-> b-> c exists:

has_child($a,'b/c');

You can also check attributes. To check if node c attribute t .

 has_child($a,'b/c/@t'); 

Answer 10

The 3 ways to confirm work in PHP 5.5.23 were to use isset() count() or empty()

Here is a script to show the results from each:

https://gist.github.com/mchelen/306f4f31f21c02cb0c24

Answer 11

Simply

 var_dump(count($xml->node)); 

Answer 12

I use a helper function to check if the node is a valid node provided as a parameter in the function.

 private static function isValidNode($node) { return isset($node) && $node instanceof SimpleXMLElement && !empty($node); } 

Usage example:

 public function getIdFromNode($node) { if (!self::isValidNode($node)) { return 0; } return (int)$node['id']; } 

Answer 13

You can try:

 if($A->b->c && $A->b->c != '') 

Answer 14

I thought I would share my experience. Running on 5.4. I tried testing with "isset" and "empty", but it didn’t work for me. I ended up using is_null .

 if(!is_null($xml->scheduler->outterList->innerList)) { //do something } 

Answer 15

Namespaces

Remember that if you use namespaces in your XML file, you will need to include them in function calls when checking for children, otherwise it will return ZERO every time:

 if ($XMLelement->children($nameSpace,TRUE)->count()){ //do something here }