Editing submitted form data in Silverstripe - silverstripe

Question

So I want to be able to have a page that is only available to the admin of the site that lists a summary of submitted forms and links to them. So once you click on the summary it takes you to an identical form that lets you edit/update the form. I have everything working except the updating part and I'm stuck.
SubmitApplication works correctly:
class SubmitApplicationPageController extends PageController{
protected function init()
{
parent::init();
}
private static $allowed_actions = [
'ApplicationForm'
];
public function ApplicationForm()
{
$fields = new FieldList(
TextField::create('First_Name')->setTitle('First Name'),
TextField::create('Last_Name')->setTitle('Last Name')
);
$actions = new FieldList(
FormAction::create('doSubmitApplication')->setTitle('Submit')
);
$validator = new RequiredFields([
'First Name',
'Last Name',
]);
return new Form($this, 'ApplicationForm', $fields, $actions, $validator);
}
public function doSubmitApplication($data, Form $form)
{
$submission = new Application();
$form->saveInto($submission);
$submission->write();
$form->sessionMessage('Thank you for your submission we will get back to you as soon as possible', 'success');
return $this->redirectBack();
}
}
Listing applications in page only available to admin:
<ul>
<% loop $Applications %>
<li>$First_Name $Last_Name View Application</li>
<% end_loop %>
</ul>
View application form for updating:
private static $allowed_actions = [
'GetApplicationForm'
];
public function GetApplicationForm(){
$var = $this->getRequest()->getVar('id');
if($var){
$fields = new FieldList(
TextField::create('First_Name')->setTitle('First Name'),
TextField::create('Last_Name')->setTitle('Last Name')
);
$actions = new FieldList(
FormAction::create('doUpdateApplication')->setTitle('Update')
);
$validator = new RequiredFields([
'First Name',
'Last Name'
]);
$form = Form::create($this, 'GetApplicationForm', $fields, $actions, $validator)->loadDataFrom(Application::get()->filter(['ID' => $var])[0]);
return $form;
}
return 'This page should only be reached through the application management links. If you are here even though you did that, please contact your system admin.';
}
public function doUpdateApplication($data, Form $form)
{
//I can't figure this part out and clicking reruns the GetApplicationForm method without the get variable and doesn't run this method
}

Answer 1

The doUpdateApplication function needs to know what record to update so you can use a hidden field.
$fields = new FieldList(
HiddenField::create('id'),
TextField::create('First_Name')->setTitle('First Name'),
TextField::create('Last_Name')->setTitle('Last Name')
);
Then you can use this id to determine which record to update.
public function doUpdateApplication($data, Form $form) {
$submission = DataList::create('Application')->byId($data['id']);
$form->saveInto($submission);
$submission->write();
//the rest of your code
}