psycopg2 OperationalError: cursor does not exist

Question

I'm trying to implement a server side cursor in order to "bypass" Django ORM weakness when it comes to fetch an huge amount of data from the database. But I don't understand how named cursor are supposed to be defined, since my current code seems not working properly. I define the cursor in this way:

id = 'cursor%s' % uuid4().hex
connection = psycopg2.connect('my connection string here')
cursor = connection.cursor(id, cursor_factory=psycopg2.extras.RealDictCursor)

The cursor seems to work in that it can be iterated and returns expected records as python dictionary, but when I try to close it (cursor.close()) I get the exception:

psycopg2 OperationalError: cursor *the generated cursor id* does not exist

WTF?! So what is the object I'm using to retrieve stuff from the database? Is psycopg2 using a fallback default (unnamed) cursor since the one I defined is not found in my database (and if so... my big question: it's mandatory to define a cursor at the db level before using psycopg2?) I'm a lot confused, can you help me?

Answer 1

I made a really simple and silly mistake of forgetting to run ./manage.py makemigrations and ./manage.py migrate before running ./manage.py test which caused this error.

(I'm aware this doesn't answer the original question, but since this is the first result from Google I thought I would contribute. Hopefully that's okay)

Answer 2

I've had this problems when playing around with my models and launching the test with Pytest.

What resolved the problem for me was to reset the database of my test unit. I used --create-db like so:

pytest backend/test_projects/partners/test_actions.py --create-db