When items are added with the DataObjectManager Module, I want them to be saved such that all uppercase letters are converted to lowercase letters.

Here is my code:

<?php

class SectionItem extends DataObject
{
	static $db = array (
		'Section' => 'Text'
	);

	public function getCMSFields_forPopup()
	{
		return new FieldSet(
			new TextField('Section')
		);
	}
}
?>

function onBeforeWrite() {
parent::onBeforeWrite();
$this->Section = strtoupper($this->Section);
}

Are you sure about that, Bambii? $this->Section refers to the current value. Since the record hasn't been written at this point, the object is still storing the old value. You need to get the value that was passed through the form. Something like $_REQUEST['Section'], for instance, but there has to be a cleaner way.