Cascade deletion won't delete GridFS file blocks used by FileField

[StoneMoe]

GridFS data blocks delete by:

mongoengine/mongoengine/document.py

Lines 642 to 644 in 92f6fce

	for name, field in self._fields.items():
	if isinstance(field, FileField):
	getattr(self, name).delete()

then

mongoengine/mongoengine/fields.py

Lines 1839 to 1844 in 92f6fce

	def delete(self):
	# Delete file from GridFS, FileField still remains
	self.fs.delete(self.grid_id)
	self.grid_id = None
	self.gridout = None
	self._mark_as_changed()

So calling Document.delete() won't ran into this issue, but cascade delete will, because:

mongoengine/mongoengine/queryset/base.py

Lines 505 to 509 in 161493c

	refs = document_cls.objects(
	**{field_name + "__in": self, "pk__nin": cascade_refs}
	)
	if refs.count() > 0:
	refs.delete(write_concern=write_concern, cascade_refs=cascade_refs)

this will call pymongo's delete directly, which will bypass file block delete logic that i referenced above