Fix QuerySet.delete() won't delete GridFS files

AUTHORS

@@ -259,6 +259,7 @@ that much better:
  * Agustin Barto (https://github.com/abarto)
  * Stankiewicz Mateusz (https://github.com/mas15)
  * Felix Schultheiß (https://github.com/felix-smashdocs)
+ * Lake Chan (https://github.com/StoneMoe)
  * Jan Stein (https://github.com/janste63)
  * Timothé Perez (https://github.com/AchilleAsh)
  * oleksandr-l5 (https://github.com/oleksandr-l5)

mongoengine/fields.py

@@ -1778,6 +1778,9 @@ def __eq__(self, other):
     def __ne__(self, other):
         return not self == other
 
+    def __hash__(self):
+        return int("{}{}".format(self.collection_name, self.grid_id).encode().hex(), 16)
+
     @property
     def fs(self):
         if not self._fs:

mongoengine/queryset/base.py

@@ -512,7 +512,20 @@ def delete(self, write_concern=None, _from_doc_delete=False, cascade_refs=None):
                 )
 
         with set_write_concern(queryset._collection, write_concern) as collection:
+            gridfs_refs = set()
+            for name, field in doc._fields.items():
+                if field.__class__.__name__ == "FileField":
+                    gridfs_refs.update(queryset.scalar(name))
+                if (
+                    field.__class__.__name__ == "ListField"
+                    and field.field.__class__.__name__ == "FileField"
+                ):
+                    for ref_list in queryset.scalar(name):
+                        gridfs_refs.update(ref_list)
+
             result = collection.delete_many(queryset._query)
+            for ref in gridfs_refs:
+                ref.delete()
 
             # If we're using an unack'd write concern, we don't really know how
             # many items have been deleted at this point, hence we only return

tests/fields/test_file_field.py

@@ -9,6 +9,7 @@
 
 from mongoengine import *
 from mongoengine.connection import get_db
+from mongoengine.fields import FileField, ListField
 
 try:
     from PIL import Image  # noqa: F401
@@ -575,6 +576,73 @@ class Animal(Document):
         assert marmot.photos[0].foo == "bar"
         assert marmot.photos[0].get().length == 8313
 
+    def test_cascade_del_filefield(self):
+        """Ensure cascade deletion also remove file chunks"""
+
+        class User(Document):
+            username = StringField()
+
+        class Album(Document):
+            user = ReferenceField("User")
+            photo = FileField()
+
+        User.register_delete_rule(Album, "user", CASCADE)
+
+        User.drop_collection()
+        Album.drop_collection()
+        self.db["fs.files"].drop()
+        self.db["fs.chunks"].drop()
+
+        user = User(username="bob").save()
+        assert User.objects.get() == user
+
+        album = Album(user=user)
+        with open(TEST_IMAGE_PATH, "rb") as img:
+            album.photo.put(img)
+        album.save()
+        assert Album.objects.get().user == user
+
+        user.delete()
+        assert User.objects.count() == 0
+        assert Album.objects.count() == 0
+        assert self.db["fs.files"].count() == 0
+        assert self.db["fs.chunks"].count() == 0
+
+    def test_cascade_del_complex_field_filefield(self):
+        """Ensure cascade deletion also remove file chunks"""
+
+        class User(Document):
+            username = StringField()
+
+        class Album(Document):
+            user = ReferenceField("User")
+            photos = ListField(FileField())
+
+        User.register_delete_rule(Album, "user", CASCADE)
+
+        User.drop_collection()
+        Album.drop_collection()
+        self.db["fs.files"].drop()
+        self.db["fs.chunks"].drop()
+
+        user = User(username="bob").save()
+        assert User.objects.get() == user
+
+        album = Album(user=user)
+        with open(TEST_IMAGE_PATH, "rb") as img:
+            photos_field = album._fields["photos"].field
+            new_proxy = photos_field.get_proxy_obj("photos", album)
+            new_proxy.put(img, content_type="image/jpeg", foo="bar")
+        album.photos.append(new_proxy)
+        album.save()
+        assert Album.objects.get().user == user
+
+        user.delete()
+        assert User.objects.count() == 0
+        assert Album.objects.count() == 0
+        assert self.db["fs.files"].count() == 0
+        assert self.db["fs.chunks"].count() == 0
+
 
 if __name__ == "__main__":
     unittest.main()