Plugins using Fred events to modify an element

1

In a plugin code, is there any way to tell Fred to find specific elements in the content and do something to them?

2

I suppose with ‘elements’ you mean Fred-elements and not html-elements.

The problem with Fred is, that the page-content is saved twice. Once unstructured in the field “content” and once structured in the field “properties”.

You can access the entire page content in the plugin with $resource->getContent(), but you probably have to find the right part to change with a regular expression.

switch ($modx->event->name) {
    case 'FredOnBeforeFredResourceSave':
        $content = $resource->getContent(); //read content
        //make changes to $content
        $resource->setContent($content); //set new content
        break;
}

You can access the Fred-elements individually in the field “properties” with $resource->getProperty() and code like this:

switch ($modx->event->name) {
    case 'FredOnBeforeFredResourceSave': 
		$data = $resource->getProperty('data', 'fred');
		$elements = &$data['content'];
		
		foreach($elements as &$element) {
			$name_element = "data-fred-name-of-element";
			if (array_key_exists($name_element,$element['values'])){
				$value = &$element['values'][$name_element]['_raw']['_value'];
				//make changes to $value
			}
		}
		//$resource->setProperty('data', $data, 'fred'); //set new value
        break;
}

But a change in the field “content” doesn’t change anything in the field “properties” and vice versa. I don’t know, if there is a way to regenerate the “content” from the “properties” in PHP, but I didn’t find anything.