Symfony2 mapping file not found - mongodb

Question

I have a little form, with just a file field to upload a document. I'm using Symfony2.6 with mongodb annotation. I get a "No mapping found for field 'file'" exception.
My document class :
namespace My\Bundle\Document;
use Doctrine\ODM\MongoDB\Mapping\Annotations as MongoDB;
use Symfony\Component\Validator\Constraints as Assert;
/**
* #MongoDB\Document
*/
class ImportFile
{
[...]
/**
* #Assert\File(maxSize = "5M", mimeTypes = {"image/jpeg", "image/gif", "image/png"})
*/
protected $file;
[...]
/**
* #return $file
*/
public function getFile()
{
return $this->file;
}
/**
* #param $file
*/
public function setFile($file)
{
$this->file = $file;
}
(the namespace is correct, i changed it for the post)
Here is my controller with my form builder :
$importFile = new ImportFile();
$form = $this->createFormBuilder($importFile)
->add('file')
->getForm();
The file field should be automatically detected (as it mentioned here http://symfony.com/doc/current/cookbook/doctrine/file_uploads.html) but it doesn't work. If i add:
$form = $this->createFormBuilder($importFile)
->add('file','file')
->getForm();
it works, but i should'nt have to add the file type as it should be automatically detected. what am i doing wrong ?

Answer 1

I think the problem is in your annotation. You added just an assert but no field definition:
/**
* #Field(type="file")
* #Assert\File(maxSize = "5M", mimeTypes = {"image/jpeg", "image/gif", "image/png"})
*/
I hope it helps.

Answer 2

As you mention here:
I don't want this field to be mapped in the database
You should use mapped property at form field definition:
mapped => false
So, this should resolved your problem ( but remeber that after submit, value from file property will not be mapped with your odm Document ):
$form = $this->createFormBuilder($importFile)
->add('file', 'file', array(
'mapped' => false
))
->getForm();
More here: http://symfony.com/doc/current/reference/forms/types/text.html#mapped