使用PHP动态更新XML

Question

So this might seem like a dumb question, but I can not find a single example of it. What I am looking for is a way to update an XML file WITHOUT knowing the names or attributes or anything about the file per say to hard code.

How I intend to do this, is I have php that reads the xml file, and creates a html form with a text field for each name + attribue combo ex:

<Tools>
        <RangeScrew Red="255" Green="192" Blue="203"/>
        <RangeRing Red="255" Green="192" Blue="203"/>
</Tools>

If it loaded something like this, it would look something like this:

So from here say I changed one of the values and clicked update value, I can pass any info to the next function, such as the name of the attribute, the node of the xml tree, or the whole node/parent combo. Since it will be heavily nested XML files.

There is a ton of examples where people hard code the path to these nodes to update them but I can't find a dynamic way. Any suggestions if I wanted to update? lets say if the example I gave was nested several deep.

Answer 1

A very simple example of what you can do with SimpleXML and updating an element in any position.

So if you wanted to update the value of the Blue attribute of <RangeScrew>, you can store a path of /Tools/RangeScrew/@Blue, which defines where it is in the hierarchy with @ to denote an attribute (this also happens to be an XPath expression). You can then use this to locate the value to update.

$source = '<Tools>
        <RangeScrew Red="255" Green="192" Blue="203"/>
        <RangeRing Red="255" Green="192" Blue="203"/>
</Tools>';

$path = "/Tools/RangeScrew/@Blue";
$value = "10";

$xml = simplexml_load_string($source);

// xpath returns a list of matches, so use [0] to get the first entry
$element = $xml->xpath($path)[0];
// Update the value (using [0] calls the magic method which allows you to set
// the value
$element[0] = $value;

echo $xml->asXML();

So this sets the Blue attribute to 10 and outputs the resultant XML...

<?xml version="1.0"?>
<Tools>
        <RangeScrew Red="255" Green="192" Blue="10"/>
        <RangeRing Red="255" Green="192" Blue="203"/>
</Tools>