chore: Django 2.0 compatibility

Author: bertonha

.travis.yml

@@ -1,12 +1,11 @@
 language: python
 python:
  - "2.7"
- - "3.4"
+ - "3.6"
 env:
-    - TOX_ENV=py27-django19
-    - TOX_ENV=py34-django19
-    - TOX_ENV=py27-django110
-    - TOX_ENV=py34-django110
+    - TOX_ENV=py27-django111
+    - TOX_ENV=py36-django111
+    - TOX_ENV=py36-django20
 install:
   - pip install tox
   - pip install "coverage>=3.7.1" coveralls

setup.py

@@ -51,7 +51,7 @@ def read_files(*filenames):
     packages=find_packages(),
     include_package_data=True,
     install_requires=[
-        'django>=1.9',
+        'django>=1.11',
         'pytz'
     ],
     cmdclass={'test': DjangoTests},
@@ -67,6 +67,7 @@ def read_files(*filenames):
         'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3.3',
         'Programming Language :: Python :: 3.4',
+        'Programming Language :: Python :: 3.6',
         'Topic :: Software Development :: Libraries :: Application Frameworks',
         'Topic :: Software Development :: Libraries :: Python Modules',
     ],

tox.ini

@@ -1,16 +1,16 @@
 [tox]
 distribute = False
 envlist =
-    {py27,py34}-django19
-    {py27,py34}-django110
+    {py27,py36}-django111
+    py36-django20
 
 
 [testenv]
 setenv = DJANGO_SETTINGS_MODULE=trackstats.tests.settings
 usedevelop = True
 deps =
-    django19: Django==1.9.9
-    django110: Django==1.10
+    django111: Django==1.11.8
+    django20: Django==2.0.1
     pytz
     coverage
 commands =

trackstats/tests/models.py

@@ -3,5 +3,5 @@
 
 
 class Comment(models.Model):
-    user = models.ForeignKey('auth.User')
+    user = models.ForeignKey('auth.User', on_delete=models.CASCADE)
     timestamp = models.DateTimeField(default=timezone.now)

trackstats/trackers.py

@@ -84,12 +84,16 @@ def track(self, qs):
             is_datetime = isinstance(qs.model._meta.get_field(
                 self.date_field), models.DateTimeField)
             if is_datetime:
-                date_sql, tz_params = connection.ops.datetime_cast_date_sql(
+                date_sql = connection.ops.datetime_cast_date_sql(
                     self.date_field,
                     tzname)
-                vals = qs.extra(
-                    select={"ts_date": date_sql},
-                    select_params=tz_params)
+                # before django 2.0 it returns a tuple
+                if isinstance(date_sql, tuple):
+                    vals = qs.extra(
+                        select={"ts_date": date_sql[0]},
+                        select_params=date_sql[1])
+                else:
+                    vals = qs.extra(select={"ts_date": date_sql})
                 start_dt = datetime.combine(
                     start_date, time()) - timedelta(days=1)
                 if tzname: