Add Django 3.0 support

* Django 3.0 - adapt `from_db_value` to satisfy method signature

See https://docs.djangoproject.com/en/3.0/releases/2.0/#deprecated-features-2-0

* Update testing configuration for Django 3.0

Author: goodtune

.travis.yml

@@ -29,6 +29,8 @@ matrix:
     env: TOXENV=py36-django111
   - python: 3.6
     env: TOXENV=py36-django22
+  - python: 3.6
+    env: TOXENV=py36-django30
   - python: 3.5
     env: TOXENV=py35-django20
   - python: 3.7
@@ -43,6 +45,10 @@ matrix:
     dist: xenial
     sudo: true
     env: TOXENV=py37-django22
+  - python: 3.7
+    dist: xenial
+    sudo: true
+    env: TOXENV=py37-django30
 install:
 - pip install tox
 script:

cloudinary/models.py

@@ -86,10 +86,11 @@ def parse_cloudinary_resource(self, value):
             format=m.group('format')
         )
 
-    def from_db_value(self, value, expression, connection, context):
-        if value is None:
-            return value
-        return self.parse_cloudinary_resource(value)
+    def from_db_value(self, value, expression, connection, *args, **kwargs):
+        # TODO: when dropping support for versions prior to 2.0, you may return
+        #   the signature to from_db_value(value, expression, connection)
+        if value is not None:
+            return self.parse_cloudinary_resource(value)
 
     def to_python(self, value):
         if isinstance(value, CloudinaryResource):

tox.ini

@@ -3,12 +3,12 @@ envlist =
   py{27,34,35,36,37}-core
   py{27,34,35}-django{18,19,110}
   py{27,34,35,36}-django{111}
-  py{36,37}-django{20,21,22}
+  py{36,37}-django{20,21,22,30}
 [testenv]
 usedevelop = True
 commands =
-  py{27,34,35,36,37}-core: python setup.py test {env:P_ARGS:}
-  py{27,34,35,36,37}-django{18,19,110,111,20,21,22}: django-admin.py test -v2 django_tests {env:D_ARGS:}
+  core: python setup.py test {env:P_ARGS:}
+  django{18,19,110,111,20,21,22,30}: django-admin.py test -v2 django_tests {env:D_ARGS:}
 passenv = *
 deps =
   django18: Django>=1.8,<1.9
@@ -18,5 +18,6 @@ deps =
   django20: Django>=2.0,<2.1
   django21: Django>=2.1,<2.2
   django22: Django>=2.2,<2.3
+  django30: Django>=3.0,<3.1
 setenv =
   DJANGO_SETTINGS_MODULE=django_tests.settings