如何使用simpleXML和php在具有特定id的节点中写入数据

Question

I found a lot of tuts here on how to get node with a specified id using XPath, and write down data using SimpleXMLElement::asXML.

But is it possible to write data in the node with specific id using XPath, but not foreach method?

Here's what I have

<people>
    <person>
        ...
    </person>
    <person id="17">
        <name>John</name>
    </person>
    <person>
        ...
    </person>
</people>

I'm looking something like:

$xml->person['id=17']->name = Bill;

or

$xml->xpath('/person[@id=17]')->name = Bill;

and then

$xml->asXML(data.xml);

Answer 1

As @Passerby points out, the ->xpath() method returns an array, so the simplest way is to loop over it with foreach (demo):

$nodes=$xml->xpath('//person[@id=17]');
foreach($nodes as $node)
{
    $node->name="Bill";
}

The objects are all linked back to the original SimpleXML parsing structure, so saving the whole thing back to XML will reflect any changes.

Since we know in this case that there is only one element in the result of the XPath, modifying $nodes[0] also works - although beware of what will happen if no nodes are found (demo):

$nodes=$xml->xpath('//person[@id=17]');
$nodes[0]->name="Bill";

The most concise version will only work in PHP 5.4, where you can use array subscripts directly on function return values, squashing the above onto one line - again, only use this if you know for sure the element will be found (demo):

$xml->xpath('//person[@id=17]')[0]->name="Bill";