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import unittest
from collections import namedtuple
from django.db import connection
from django.test import TestCase
from .models import Person
@unittest.skipUnless(connection.vendor == 'postgresql', "Test only for PostgreSQL")
class ServerSideCursorsPostgres(TestCase):
cursor_fields = 'name, statement, is_holdable, is_binary, is_scrollable, creation_time'
PostgresCursor = namedtuple('PostgresCursor', cursor_fields)
@classmethod
def setUpTestData(cls):
Person.objects.create(first_name='a', last_name='a')
Person.objects.create(first_name='b', last_name='b')
def inspect_cursors(self):
with connection.cursor() as cursor:
cursor.execute('SELECT {fields} FROM pg_cursors;'.format(fields=self.cursor_fields))
cursors = cursor.fetchall()
return [self.PostgresCursor._make(cursor) for cursor in cursors]
def test_server_side_cursor(self):
persons = Person.objects.iterator()
next(persons) # Open a server-side cursor
cursors = self.inspect_cursors()
self.assertEqual(len(cursors), 1)
self.assertIn('_django_curs_', cursors[0].name)
self.assertFalse(cursors[0].is_scrollable)
self.assertFalse(cursors[0].is_holdable)
self.assertFalse(cursors[0].is_binary)
def test_server_side_cursor_many_cursors(self):
persons = Person.objects.iterator()
persons2 = Person.objects.iterator()
next(persons) # Open a server-side cursor
next(persons2) # Open a second server-side cursor
cursors = self.inspect_cursors()
self.assertEqual(len(cursors), 2)
for cursor in cursors:
self.assertIn('_django_curs_', cursor.name)
self.assertFalse(cursor.is_scrollable)
self.assertFalse(cursor.is_holdable)
self.assertFalse(cursor.is_binary)
def test_closed_server_side_cursor(self):
persons = Person.objects.iterator()
next(persons) # Open a server-side cursor
del persons
cursors = self.inspect_cursors()
self.assertEqual(len(cursors), 0)
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