A flask-admin bug report concerning FileUploadField

app.py

from functools import partial
from os import remove
from os.path import join

from flask import Flask
from flask.ext.admin import Admin, form
from flask.ext.admin.contrib.sqla import ModelView
from flask.ext.sqlalchemy import SQLAlchemy

from sqlalchemy.event import listens_for

app = Flask( __name__ )
app.config[ 'SECRET_KEY' ] = '123456790'
app.config[ 'SQLALCHEMY_DATABASE_URI' ] = 'sqlite:////tmp/db.sql'

BASE_PATH = '/tmp'

db = SQLAlchemy( app )

class ModelWithUpload( db.Model ):
	id = db.Column( db.Integer, primary_key = True )
	model_path = db.Column( db.String )

@listens_for( ModelWithUpload, 'after_delete' )
def del_file( mapper, connection, target ):
	if target.model_path:
		try:
			remove( join( BASE_PATH, target.model_path ) )
		except OSError:
			pass

class ViewWithUpload( ModelView ):
	form_overrides = {
        'model_path': partial( form.FileUploadField, allowed_extensions = ( 'txt', ) )
    }
	form_args = {
		'model_path': {
			'label': 'A file',
			'base_path': BASE_PATH
		}
    }

db.drop_all()
db.create_all()

admin = Admin( app, template_mode='bootstrap3' )
admin.add_view( ViewWithUpload( ModelWithUpload, db.session ) )
app.run( host = '0.0.0.0', port = 8000, debug = True )