ModelAdmin implementation Example
=================

```php
/**** MyModelAdmin.php ****/
class MyModelAdmin extends ModelAdmin {
    private static $menu_title = 'My Model Admin';
    
    private static $url_segment = 'my-model-admin';
    
    private static $managed_models = array(
        'MATestObject',
    );
    
    public function getEditForm($id = null, $fields = null) {
        $form = parent::getEditForm($id, $fields);
        
        //This check is simply to ensure you are on the managed model you want adjust accordingly
        if($this->modelClass == 'MATestObject' && $gridField=$form->Fields()->dataFieldByName($this->sanitiseClassName($this->modelClass))) {
            //This is just a precaution to ensure we got a GridField from dataFieldByName() which you should have
            if($gridField instanceof GridField) {
                $gridField->getConfig()->addComponent(new GridFieldSortableRows('SortOrder'));
            }
        }
        
        return $form;
    }
}

/**** MATestObject.php ****/
class MATestObject extends DataObject {
    private static $db = array(
        'Title' => 'Varchar',
        'SortOrder' => 'Int',
    );
    
    private static $default_sort = 'SortOrder';
}
```