Joomla onContentBeforeSave Data to xml not working - joomla

Question

I've set up a plugin that should retrieve some data from the form and save it to an xml file. I had tried the code by itself and it worked, but then when I've inserted it into a plugin with the method onContentBeforeSave, it doesn't work anymore.
Here's the code of the plugin, I've no idea of what's not working!
defined('_JEXEC') or die();
jimport('joomla.plugin.plugin');
class plgContentsave2xml extends JPlugin
{
public function __construct($subject, $config)
{ parent::__construct($subject, $config);
}
function onContentBeforeSave($context, &$article, $isNew)
{ global $mainframe;
if(isset($_POST['create_xml']))
{
$doc = new DOMDocument('1.0');
// Formatting the file
$doc->formatOutput = true;
$doc->encoding = "Utf-8";
$field = $_POST['field'];
$field = utf8_encode($field);
$part = $doc->createElement('part');
$part = $doc->appendChild($part);
$field = $doc->createElement('field');
$field = $part->appendChild($field);
$text = $doc->createTextNode($field);
$text = $field->appendChild($text);
}
echo $doc->save('xmlf/' . 'test' . '.xml');
}
return true;
}
}
?>

Answer 1

I think you shouldn't output anything from within your code, and you have a line where you output (or might output) data.
Another point is that you are not checking the context, do you want the code to be execute for articles, categories, etc., or only for articles?
If it's only for articles, you should check if context equals "com_content.article":
if ( $context != "com_content.article" ) { return; }
One last thing. Are you adding fields to your article/category form via the "onContentPrepareForm" event?
If so, you should get your data like this:
function onContentBeforeSave( $context, &$row, $isNew ) {
if ( $context != "com_content.article" ) {
return;
}
jimport( 'joomla.html.parameter' );
$params = new JParameter( $row->attribs );
$create_xml = $params->get( 'create_xml', false );
if ( $create_xml ) {
$field = $params->get( 'field', '');
// The rest of your code here...
//If you don't want these fields to be stored with the params of the article:
$params->set( 'field', '' );
$params->set( 'create_xml', '' );
}
$row->attribs = (string)$params;
return;
}
Besides, if you're not using the "onContentPrepareForm", you can implement it like this:
function onContentPrepareForm($form, $data)
{
$return = true;
if (!($form instanceof JForm))
{
$this->_subject->setError('JERROR_NOT_A_FORM');
$return = false;
} elseif ( $form->getName() != 'com_content.article' ) {
$return = true;
} else {
// Add the registration fields to the form.
JForm::addFormPath( __DIR__ . DIRECTORY_SEPARATOR . 'form' );
$form->loadFile('your_file', false);
$return = true;
}
return $return;
}
You should have a file inside your plugin folder: plugin_folder/form/your_file.xml, with this form:
<?xml version="1.0" encoding="utf-8"?>
<form>
<fields name="attribs">
<fieldset name="create_xml" label="Create XML">
<field name="create_xml" [...]>
<field name="field" [...]>
</fieldset>
</fields>
</form>
I hope it helped!