pymodm can't find an object, while pymongo successfully finds it - python-3.x

Question

I have a problem getting an object from the mongodb instance. If I search for this object with pymongo interface, everything is fine - object can be found. If try to do the very same thing with pymodm - it fails with error.
Here is what I'm doing:
from pymodm import connect, MongoModel, fields
from pymongo import MongoClient
class detection_object(MongoModel):
legacy_id = fields.IntegerField()
client = MongoClient(MONGODB_URI)
db = client[MONGODB_DEFAULT_SCHEME]
collection = db['detection_object']
do = collection.find_one({'legacy_id': 1437424})
print(do)
connect(MONGODB_URI)
do = detection_object.objects.raw({'legacy_id': 1437424}).first()
print(do)
The first print outputs this: {'_id': ObjectId('5c4099dcffa4fb11494d983d'), 'legacy_id': 1437424}. However, during the execution of this command: do = detection_object.objects.raw({'legacy_id': 1437424}).first() interpreter fails with the following error:
Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/pymodm/queryset.py", line 127, in first
return next(iter(self.limit(-1)))
StopIteration
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/konsof01/PycharmProjects/testthisfuckingshit/settings.py", line 29, in <module>
do = detection_object.objects.raw({'legacy_id': 1437424}).first()
File "/usr/local/lib/python3.7/site-packages/pymodm/queryset.py", line 129, in first
raise self._model.DoesNotExist()
__main__.DoesNotExist
How can this be? I'm trying to query the very same object, with the same connection and collection. Any ideas, please?

Answer 1

you could try it as follows:
detection_object.objects.raw({'legacy_id': "1437424"} ).first()
probably the legacy_id is stored as string.
Othewise, make sure the db name is present at the end of the MONGO_URI as it is underlined in the docs.

Answer 2

Each document in your 'detection_object' collection requires to have '_cls' attribute. The string value stored in this attribute should be
__main__.classname
(class name according to your code is detection_object).
For example a document in your database needs to look like this:
{'_id': ObjectId('5c4099dcffa4fb11494d983d'), 'legacy_id': 1437424, '_cls': '__ main __.detection_object'}