PHP SimpleXML: insert node at certain position

The following is a function to insert a new SimpleXMLElement after some other SimpleXMLElement. Since this isn't directly possible with SimpleXML, it uses some DOM classes/methods behind-the-scenes to get the job done.

function simplexml_insert_after(SimpleXMLElement $insert, SimpleXMLElement $target)
{
    $target_dom = dom_import_simplexml($target);
    $insert_dom = $target_dom->ownerDocument->importNode(dom_import_simplexml($insert), true);
    if ($target_dom->nextSibling) {
        return $target_dom->parentNode->insertBefore($insert_dom, $target_dom->nextSibling);
    } else {
        return $target_dom->parentNode->appendChild($insert_dom);
    }
}

And an example of how it might be used (specific to your question):

$sxe = new SimpleXMLElement('<root><nodeA/><nodeA/><nodeA/><nodeC/><nodeC/><nodeC/></root>');
// New element to be inserted
$insert = new SimpleXMLElement("<nodeB/>");
// Get the last nodeA element
$target = current($sxe->xpath('//nodeA[last()]'));
// Insert the new element after the last nodeA
simplexml_insert_after($insert, $target);
// Peek at the new XML
echo $sxe->asXML();

If you want/need an explanation of how this works (the code is fairly simple but might include foreign concepts), just ask.

So basically what you need to do is a function that takes each <asset/> child of current node, builds the HTML then checks if the current node has <asset/> children of its own and keeps recursing deeper down the tree.

Here's how you can do it:

function printAssetMap()
{
    return printAssets(simplexml_load_file(X_ASSETS));
}

function printAssets(SimpleXMLElement $parent)
{
    $html = "<ul>n";
    foreach ($parent->asset as $asset)
    {
        $html .= printAsset($asset);
    }
    $html .= "</ul>n";

    return $html;
}

function printAsset(SimpleXMLElement $asset)
{
    $html = '<li id="asset'.$asset->asset_assetid.'"><ins>&nbsp;</ins><a href="#">'.$asset->asset_name.' ['.$asset->asset_assetid.']</a>';

    if (isset($asset->asset))
    {
        // has <asset/> children
        $html .= printAssets($asset);
    }

    $html .= "</li>n";

    return $html;
}

By the way, I would expect a function named "printX" to actually print or echo something, rather than return it. Perhaps you should name those functions "buildX" ?

Actually your code should work - in order to add a sub node you just have to do:

myNode.Nodes.Add(new TreeNode("Sub node"));

Maybe the problem is in the way you refer to your existing nodes. I am guessing that tree.Nodes[item.Name] returned null?

In order for this indexer to find the node, you need to specify a key when you add the node. Did you specify the node name as a key? For example, the following code works for me:

treeView1.Nodes.Add("key", "root");
treeView1.Nodes["key"].Nodes.Add(new TreeNode("Sub node"));

If my answer doesn't work, can you add more details on what does happen? Did you get some exception or did simply nothing happen?

PS: in order to store an object in a node, instead of using the Tag property, you can also derive your own class from TreeNode and store anything in it. If you're developing a library, this is more useful because you are leaving the Tag property for your users to use.

Ran