Question

Is there a way to add a custom form element to a Magento Adminhtml form without placing the custom element in the lib/Varian folder?

I’ve tracked down the code that’s essentially a Varian_Data_Form_Element_ factory

public function addField($elementId, $type, $config, $after=false)
{
    if (isset($this->_types[$type])) {
        $className = $this->_types[$type];
    }
    else {
        $className = 'Varien_Data_Form_Element_'.ucfirst(strtolower($type));
    }
    $element = new $className($config);
    $element->setId($elementId);
    if ($element->getRequired()) {
        $element->addClass('required-entry');
    }
    $this->addElement($element, $after);
    return $element;
}

So, if I’m reading this correctly, I ensure that an EAV attribute’s frontend returns a specific fieldType, (such as supertextfield) and the system will instantiate/render a Varien_Data_Form_Element_Supertextfield when displaying this attribute’s editing form.

This is well and good, but it means I need to include my custom form element in the lib/Varian folder hierarchy. Given how module oriented Magento is, it seems like this is doing it wrong.

I realize I could jank around with a custo autoloader or symlinks in the lib, but I’m primarily interested in learning if there’s

1. A canonical way to add custom form elements for attributes

2. A canonical way to customize the Magento autoloader.

Answer 1

Self help desk strikes again. It looks like Magento sets up include paths in such a way that you can drop class files from lib (not just from the Mage_ namespace) in your local code branch

app/code/local/Varien/etc

When the autoloader tries to load a lib/Varien class, it will check your directory first. This still puts you at risk if Varien ever creates a data element with the same name as yours, but as risks go it’s relatively low.