I've set up a gridfield, and there is an image upload field on it... wanted to set it so that only PNG files could be uploaded, and also to specify the upload folder for the files... but it's totally ignoring the validator and the config. I can upload any type of file, and they just go into assets/uploads default folder... argh!

BannerImage.php:

<?php

class BannerImage extends DataObject {

	// objects fields
	public static $db = array(
		'Title' => 'Varchar(255)'
	);

	// One-to-one relationship with picture and list page
	public static $has_one = array(
		'Banner' => 'Image',
		'Homepage' => 'Homepage'
	);

	// Summary fields for CMS Gridlist
	public static $summary_fields = array(
		'Banner.StripThumbnail' => 'Image',
		'Title' => 'Title'
	);
	

	static $default_sort = "ID DESC";
	
	public function getCMSFields_forPopup() {

		// define picture field
		$bannerField = new UploadField('Banner', 'Banner');
        $bannerField->setFolderName('assets/Uploads/HomepageElements/Banners');
		$bannerField->getValidator()->setAllowedExtensions(array('png'));


		// Define all fields
		return new FieldList(
			new TextField('Title', 'Title'),
			$bannerField
		);
	}

}

and on Homepage.php:

<?php
/**
 * Defines the Homepage page type
 */
 
class Homepage extends Page {

	// One to many relationship with banner object
	public static $has_many = array(
		'BannerImages' => 'BannerImage'
	);
	
   static $db = array(
   );
   
   
   static $has_one = array(
   );
   
	public static $many_many = array(
	); 

   static $icon = "framework/docs/en/tutorials/_images/treeicons/home-file.gif";
   
	// Create Grid Field
	public function getCMSFields() {
		$fields = parent::getCMSFields();
		
		$fields->removeFieldFromTab("Root.Admin", "ShowInDropDown"); 
		$fields->removeFieldFromTab("Root.Admin", "ShowListings"); 
		$fields->removeFieldFromTab("Root.Admin", "CustomBanner"); 
		$fields->removeFieldFromTab("Root.Admin", "CategoryImage"); 
		
		$gridFieldConfig2 = GridFieldConfig::create()->addComponents(
			new GridFieldToolbarHeader(),
			new GridFieldAddNewButton('toolbar-header-right'),
			new GridFieldSortableHeader(),
			new GridFieldDataColumns(),
			new GridFieldPaginator(10),
			new GridFieldEditButton(),
			new GridFieldDeleteAction(),
			new GridFieldDetailForm()
		);
		
		$gridField = new GridField("BannerImages", "Banners:", $this->BannerImages(), $gridFieldConfig2);
		$fields->addFieldToTab("Root.Admin", $gridField);
		return $fields;
	}
 
}
 
class Homepage_Controller extends Page_Controller {
	
	
	function RandomSliders($num = 4) { 
			 return DataObject::get("BannerImage", "", "RAND()", "",$num); 
	}

}
?>

Anyone got any suggestions? Ta, L xxx

GridField doesn't use getCMSFields_forPopup. You just override getCMSFields(), use $fields = parent::getCMSFields() and add/remove/update fields from there.