Folder images in xblock

I’m traying to save an image on folder named media, by uploading the image from a form.
But the folder media/uploads is created inside the xblock-sdk and I want it to be in the app folder not in xblock-sdk folder.

this is my model

figure = models.ImageField(upload_to='images/%Y/%m',

in my workbench/ file
I add :

MEDIA_ROOT = os.path.join(BASE_DIR, 'media/') 
MEDIA_URL = '/media/'

How I can have the media folder in my app folder.