Update utils.py (#225)

* Update utils.py

verify get_meta isn't none before requesting db_table

* Add passenv to tox.ini

* Fix test_explain in sqlite

---------

Co-authored-by: Andrew Chen Wang <60190294+Andrew-Chen-Wang@users.noreply.github.com>

cachalot/tests/read.py

@@ -907,7 +907,7 @@ class ReadTestCase(TestUtilsMixin, TransactionTestCase):
     def test_explain(self):
         explain_kwargs = {}
         if self.is_sqlite:
-            expected = (r'\d+ 0 0 SCAN TABLE cachalot_test\n'
+            expected = (r'\d+ 0 0 SCAN cachalot_test\n'
                         r'\d+ 0 0 USE TEMP B-TREE FOR ORDER BY')
         elif self.is_mysql:
             if self.django_version < (3, 1):

cachalot/utils.py

@@ -217,7 +217,8 @@ def _get_tables(db_alias, query, compiler=False):
 
         # Gets all tables already found by the ORM.
         tables = set(query.table_map)
-        tables.add(query.get_meta().db_table)
+        if query.get_meta():
+            tables.add(query.get_meta().db_table)
 
         # Gets tables in subquery annotations.
         for annotation in query.annotations.values():

tox.ini

@@ -7,6 +7,7 @@ envlist =
     py{38,39,310}-djangomain-{sqlite3,postgresql,mysql}-{redis,memcached,pylibmc,locmem,filebased},
 
 [testenv]
+passenv = *
 basepython =
     py37: python3.7
     py38: python3.8