Hi there, I have extended class "File" to class "VideoFile" (which does some automatic screenshots after the upload etc).

Now I have also recognized how to use the Uploadfield (the Ajax Stuff) on the Frontend.

Here is now my Problem:
I create an Object Movie, which has a relation to one Video of class VideoFile

class Movie extends DataObject{
static private $db = array("Title" => "Varchar(255)");
static private $has_one = array("Video" => "VideoFile");
}

Adding Movies to the collection by using ModelAdmin in the Backend, when creating a new Movie, the relation is set correctly and the File gets saved as type VideoFile on upload (even if I did not saved the Movie Object previously).

When creating a Form in the Frontend, I can also use UploadField for the File, but how do I tell it, that the Uploaded File should be of Type VideoFile.
Normaly, when the Form is created, the relation to the Object that it will create (Movie) will be set, when the form was submitted and the method saveInto is run on a Movie Object.

Would be nice, if smeone can help me, finding the right parts in the code, that I have to write an extension for.

kind regards

mysite/_config/config.yml

File:
  class_for_file_extension:
    'mp4': 'VideoFile'
    'm4v': 'VideoFile'

Thats one possible way, but with the downside, that I always have to use the VideoFile Object, when uploading files.

I was more thinking of a way, o be more flexible here. When the Object has the relation with VideoFile, than the Uploaded File should be of this class, otherwise the uploaded File should be of File class.

When Setting up a ModelAdmin, the File class is taken from the relationship, even if I do not set it i "class_for_file_extensions" separately.

class MovieAdmin extends ModelAdmin {

private static $managed_models = array('Movie');
private static $url_segment = 'testmovie';
private static $menu_title = 'Movie Test';

}

I tried to reverse engeneer the ModelAdmin and have examined, that ModelAdmin::getEditForm seems to be the Method, where regarding to the relation on the Parent Object (in my case "Movie"), the File is saved with the correct class (VideoFile).

Now my frontendform looks the following:
class MovieForm extends Form {
public function __construct($controller, $name) {
$fields = new FieldList(
$Title = new TextField('Title', 'Title'),
$File = new UploadField('Video', 'Video File')
);

$actions = new FieldList(new FormAction('save', 'Save video'));
$validator = new RequiredFields(array("Title"));

parent::__construct($controller, $name, $fields, $actions, $validator);
}
public function save(array $data, Form $form) {
$Movie = new Movie();
$form->saveInto($Movie)
...
}
}

I'm sure, I can set some kind of validator, to set the correct class for the File, but I do not know how to do it. So if anyone can help me, to examine how the ModelAdmin is selecting the right class by the Parent Models Relationships, that would be really cool.

how the ModelAdmin is selecting the right class

ModelAdmin doesn't do this.

The UploadField determines the file class by comparing the name of the UploadField with the names of the relations you've defined in the current DataObject.

- UploadField->getRelationAutosetClass()
- DataObject->getRelationClass()

You could overload UploadField->getRelationAutosetClass() to return "VideoFile".

You could try to set the record for the form. e.g.

$form = new Form();
$form->loadDataFrom($myRecord);
// or
$form->setDataModel(singleton('myObject'));

Edit 2: According to the documentation, this should be sufficient.
$movie = new Movie();
$form->saveInto($movie);
$movie->write();

http://doc.silverstripe.org/framework/en/reference/uploadfield#using-the-uploadfield-in-a-frontend-form

Thanks Devlin, you've safed my day defnetly.

Hint: If you're using the UploadField in the frondend, you really need to set permissions to your File DataObject or bad things will happen.

Wll, thanks.

One more thing to add:

$form->setDataModel(singleton('myObject'));
setting the DataModel didn't helped in my case, but without allready having an object, where I can load the Form from, the singleton method had helped at this place.

class MovieForm extends Form {
public function __construct($controller, $name) {
$fields = new FieldList(
$Title = new TextField('Title', 'Title'),
$File = new UploadField('Video', 'Video File')
);

$actions = new FieldList(new FormAction('save', 'Save video'));
$validator = new RequiredFields(array("Title"));

parent::__construct($controller, $name, $fields, $actions, $validator);
$form->loadDataFrom(singleton('Movie'));
}
public function save(array $data, Form $form) {
$Movie = new Movie();
$form->saveInto($Movie)
...
}
}

So thanks again