Bulk uploading with images for SilverStripe

real-estate.csv

RealEstateOffice.php

<?php 
/** 
* RealEstateOffice Class
*/ 
class RealEstateOffice extends DataObject {
   	private static $singular_name = "Real Estate Office"; 
   	private static $plural_name = "Real Estate Offices";

  	private static $db = array(
      	'OfficeName' => 'Varchar(100)'
   	);

   	private static $has_one = array( 
      	'OfficeLogo' => 'Image'
   	);

	private static $summary_fields = array(
    	'OfficeName',
    	'OfficeLogo'
	);   
}

/*
* RealEstateOfficeAdmin Class
*/

class RealEstateOfficeAdmin extends ModelAdmin {
    
    private static $managed_models = array( 
        'RealEstateOffice'
    );

   private static $model_importers = array(
      'RealEstateOffice' => 'RealEstateOfficeCsvBulkLoader'
   );    
    
    private static $url_segment = 'realestateoffices';
    private static $menu_icon = 'framework/admin/images/menu-icons/16x16/document.png';
    private static $menu_title = 'Real Estate Offices';
}

RealEstateOfficeCsvBulkLoader.php

<?php
/** 
* RealEstateOfficeCsvBulkLoader Class Bulk CSV uploading
*/

class RealEstateOfficeCsvBulkLoader extends CsvBulkLoader {
   	public $columnMap = array(
		'Office Name' => 'OfficeName',
		'Logo Filename' => 'OfficeLogo.Filename'
   	);

   	public $relationCallbacks = array(
      	'OfficeLogo.Filename' => array(
			'relationname' => 'OfficeLogo',
			'callback' => 'getImageByFilename'
      	)
   	);

  	public static function getImageByFilename(&$obj, $val, $record) {
  		return Image::get()->filter('Filename', $val)->First();
   	}
}