set value for a field after the form is rendered in processForm

I want to set a userID while a form is processed in processForm, located in actions.class.php. The problem is, I have unset the userID field and somehow I can't set a value for that. I've searched but I couldn't find anything useful.

I don't want to set the value in a hidden field or something like this, since the userID isn't the only value I want to set. Some values are based开发者_开发问答 on the form request itself.

Thanks.

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You can change fields right after the binding - for example this is in my processForm method

$form->bind($request->getParameter($form->getName()), $request->getFiles($form->getName()));
if ($form->isValid())
{
  $model = $form->save();
  $model->setField(value);
  $model->save();
}

Ensure you call the save() method else the changes wont be visible