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Date: Tue, 22 May 2007 11:23:02 +0300
To: internals@lists.php.net, "Vesselin Kenashkov" <kenashkov@gmail.com>
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Subject: unexpected behaviour in SimpleXML (php 5.2.2)
From: kenashkov@gmail.com ("Vesselin Kenashkov")

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Hello everybody,

Before writing to the dev-list I posted a message in the Zend dev forum (in
fact it was an year ago about the same issues), as well on PHP general list,
but without any reply or comment. I think two things in the SimpleXML are
inconsistent, or at least unexpected from the php developer.

Here is the first one - how one can find does a SimpleXMLElement has child
nodes?
Here is an example:
--------
$str = '<rootnode><subnode></subnode></rootnode>';
$x = new SimpleXMLElement($str);

if($x->subnode->children())
    print 'yes';
    else
        print 'no';
---------
will print 'no';

If the
$str='<rootnode><subnode><newnode></newnode></subnode></rootnode>';
it will print yes.
But the same will happen if the subnode has an attribute like:
$str = '<rootnode><subnode id="2"></subnode></rootnode>';

But if we use foreach($x->subnode->children() as $key=>$value)
in the latter example we will not get anything (which is correct).
I think is wrong the children() method to return object when there are no
child objects and the node has attributes.

The workaround I use is to extend the SimpleXMLElement
--------
class SimpleXMLElement2 extends SimpleXMLElement
{
public function has_children()
    {
    foreach($this->children() as $node)
        return true;
    return false;
    }

}
------
And then we can check with if($x->subnode->has_children())



Issue #2:
Xpath on nodes.
Let we have the example:
-----------------
$str =
'<rootnode><level1_node1><level2_node1></level2_node1></level1_node1><level1_node2></level1_node2></rootnode>';

$x = new SimpleXMLElement($str);

$r1 = $x->xpath('/*');
print $r1[0]->getName();//prints rootnode

$r2 = $x->level1_node1[0]->xpath('/*');
print $r2[0]->getName();//prints rootnode

$z = clone $x->level1_node1[0];
$r3 = $z->xpath('/*');
print $r3[0]->getName();//prints rootnode

//print $z->getName();//ok
------------------
I personally think that the xpath must be evaluated against the node which
method is called, not always against the rootnode.
So in the second example I would expect it to return level1_node1, and
especially in the thirds example.
Even in the third example the xpath is evaluated against the original XML
structure, not the subnode (level1_node1).
I think this is incorrect and leads to a confusion - for example we can pass
a node to a function like:
--------
function do_something($node)
    {
    //print $node->getName();//prints correct - the name of the supplied
node - level1_node1
    $r1 = $node->xpath('/*');
    print $r1[0]->getName();
    }

do_something(clone $x->level1_node1[0]);
--------
The do_something function is not aware at all about the full xml structure
and one could think that the expression will be evaluated just against the
supplied node, but it is not that the case.

Please give your comments - do you find this functionality OK, is it a bug,
or I miss something.


Vesselin Kenashkov

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