Updates for compatibility with Django3 and dropping support for Python2.

Updates for compatibility with Django3 and dropping support for Python2.

.circleci/config.yml

@@ -32,160 +32,76 @@ jobs:
   lint:
     <<: *common
     docker:
-      - image: circleci/python:3.7
+      - image: circleci/python:3.8
         environment:
           - TOXENV=checkqa
           - UPLOAD_COVERAGE=0
-  py27dj18:
-    <<: *common
-    docker:
-      - image: circleci/python:2.7
-        environment:
-          TOXENV=py27-dj18
-  py27dj110:
-    <<: *common
-    docker:
-      - image: circleci/python:2.7
-        environment:
-          TOXENV=py27-dj110
-  py27dj111:
-    <<: *common
-    docker:
-      - image: circleci/python:2.7
-        environment:
-          TOXENV=py27-dj111
-  py34dj18:
-    <<: *common
-    docker:
-      - image: circleci/python:3.4
-        environment:
-          TOXENV=py34-dj18
-  py34dj110:
-    <<: *common
-    docker:
-      - image: circleci/python:3.4
-        environment:
-          TOXENV=py34-dj110
-  py34dj111:
-    <<: *common
-    docker:
-      - image: circleci/python:3.4
-        environment:
-          TOXENV=py34-dj111
-  py34dj20:
-    <<: *common
-    docker:
-      - image: circleci/python:3.4
-        environment:
-          TOXENV=py34-dj20
-  py35dj18:
-    <<: *common
-    docker:
-      - image: circleci/python:3.5
-        environment:
-          TOXENV=py35-dj18
-  py35dj110:
-    <<: *common
-    docker:
-      - image: circleci/python:3.5
-        environment:
-          TOXENV=py35-dj110
-  py35dj111:
-    <<: *common
-    docker:
-      - image: circleci/python:3.5
-        environment:
-          TOXENV=py35-dj111
-  py35dj20:
-    <<: *common
-    docker:
-      - image: circleci/python:3.5
-        environment:
-          TOXENV=py35-dj20
-  py35dj21:
-    <<: *common
-    docker:
-      - image: circleci/python:3.5
-        environment:
-          TOXENV=py35-dj21
-  py35dj22:
+  py36dj22:
     <<: *common
     docker:
-      - image: circleci/python:3.5
+      - image: circleci/python:3.6
         environment:
-          TOXENV=py35-dj22
-  py36dj111:
+          TOXENV=py36-dj22
+  py36dj30:
     <<: *common
     docker:
       - image: circleci/python:3.6
         environment:
-          TOXENV=py36-dj111
-  py36dj20:
+          TOXENV=py36-dj30
+  py36djmaster:
     <<: *common
     docker:
       - image: circleci/python:3.6
         environment:
-          TOXENV=py36-dj20
-  py36dj21:
+          TOXENV=py36-djmaster
+  py37dj22:
     <<: *common
     docker:
-      - image: circleci/python:3.6
+      - image: circleci/python:3.7
         environment:
-          TOXENV=py36-dj21
-  py36dj22:
+          TOXENV=py37-dj22
+  py37dj30:
     <<: *common
     docker:
-      - image: circleci/python:3.6
+      - image: circleci/python:3.7
         environment:
-          TOXENV=py36-dj22
-  py37dj111:
+          TOXENV=py37-dj30
+  py37djmaster:
     <<: *common
     docker:
       - image: circleci/python:3.7
         environment:
-          TOXENV=py37-dj111
-  py37dj20:
+          TOXENV=py37-djmaster
+  py38dj22:
     <<: *common
     docker:
-      - image: circleci/python:3.7
+      - image: circleci/python:3.8
         environment:
-          TOXENV=py37-dj20
-  py37dj21:
+          TOXENV=py38-dj22
+  py38dj30:
     <<: *common
     docker:
-      - image: circleci/python:3.7
+      - image: circleci/python:3.8
         environment:
-          TOXENV=py37-dj21
-  py37dj22:
+          TOXENV=py38-dj30
+  py38djmaster:
     <<: *common
     docker:
-      - image: circleci/python:3.7
+      - image: circleci/python:3.8
         environment:
-          TOXENV=py37-dj22
+          TOXENV=py38-djmaster
 
 workflows:
   version: 2
   test:
     jobs:
       - lint
-      - py27dj18
-      - py27dj110
-      - py27dj111
-      - py34dj18
-      - py34dj110
-      - py34dj111
-      - py34dj20
-      - py35dj18
-      - py35dj110
-      - py35dj111
-      - py35dj20
-      - py35dj21
-      - py35dj22
-      - py36dj111
-      - py36dj20
-      - py36dj21
       - py36dj22
-      - py37dj111
-      - py37dj20
-      - py37dj21
+      - py36dj30
+      - py36djmaster
       - py37dj22
+      - py37dj30
+      - py37djmaster
+      - py38dj22
+      - py38dj30
+      - py38djmaster

README.md

@@ -215,6 +215,50 @@ AppleSerializer(instance=instance).data
 
 ```
 
+## Gotchas
+
+### Setting a field on a model to the value of a constant rather than the Constant object
+
+When the Django ORM instantiates a model instance from the database, it will ensure that any `ConstantChoiceField` or `ConstantChoiceCharField` fields have values set to `Constant` instances.
+
+If you create or modify a model instance using a raw, hard-coded constant value, you're likely to hit errors along the lines of "AttributeError: 'int' object has no attribute 'attribute-name'".
+
+Take the example below where the caller sets the colour of a model instance to the underlying value for the `Constant`:
+
+```python
+apple = Apple.objects.get(name='Granny Smith')
+apple.purpose = 1  # constant for `eating` .. I know, who on earth would eat a granny smith straight up?!
+apple.save()
+```
+
+Django will happily persist the data correctly, but let's say you have a `post_save` signal (or any other code, really) that does something further with the instance:
+
+```python
+from django.db.models.signals import post_save
+from django.dispatch import receiver
+
+from .models import Apple
+
+@receiver(post_save, sender=Apple)
+def apple_updated_receiver(sender, instance, created, *args, **kwargs):
+    if not created and instance.purpose.eating:
+        print(f"Oh my, {instance.name} is now for eating!")
+
+```
+
+This code will sadly raise `AttributeError: 'int' object has no attribute 'purpose'`, as `instance.purpose` is just the integer we set it to before saving.
+
+The good news is that you can avoid this by *always* setting `django-konst` fields on instances to `Constant` instances such that downstream code can happily handle the instance as if it'd come straight out of the database:
+
+```python
+apple = Apple.objects.get(name='Granny Smith')
+apple.purpose = Apple.purposes.eating
+apple.save()
+```
+
+Regardless of whether you're using `django-konst` for your constants, it's good practice to not hard-code constant values in order to avoid subtle mistakes and to ease changes in the future.
+
+
 ## Contribute
 
 `django-konst` supports a variety of Python and Django versions. It's best if you test each one of these before committing. Our [Circle CI Integration](https://circleci.com) will test these when you push but knowing before you commit prevents from having to do a lot of extra commits to get the build to pass.
@@ -225,31 +269,28 @@ In order to easily test on all these Pythons and run the exact same thing that C
 
 If you are on Mac OS X, it's recommended you use [brew](http://brew.sh/). After installing `brew` run:
 
-```
-$ brew install pyenv pyenv-virtualenv pyenv-virtualenvwrapper
+```bash
+brew install pyenv pyenv-virtualenv pyenv-virtualenvwrapper
 ```
 
-Then:
+Next, install the various python versions we want to test against and create a virtualenv specifically for `django-konst`:
 
-```
-pyenv install -s 2.7.14
-pyenv install -s 3.4.7
-pyenv install -s 3.5.4
-pyenv install -s 3.6.3
-pyenv virtualenv 2.7.14
-pyenv virtualenv 3.4.7
-pyenv virtualenv 3.5.4
-pyenv virtualenv 3.6.3
-pyenv global 2.7.14 3.4.7 3.5.4 3.6.3
+```bash
+pyenv install 3.6.10
+pyenv install 3.7.6
+pyenv install 3.8.1
+pyenv virtualenv 3.8.1 konst
+pyenv activate konst
 pip install detox
+pyenv shell konst 3.6.10 3.7.6
 ```
 
-To run test suite:
+Now ensure the `konst` virtualenv is activated, make the other python versions also on our path, and run the tests!
 
-Make sure you are NOT inside a `virtualenv` and then:
 
-```
-$ detox
+```bash
+pyenv shell konst 3.6.10 3.7.6
+detox
 ```
 
-This will execute the testing matrix in parallel as defined in the `tox.ini`.
+This will execute the test environments in parallel as defined in the `tox.ini`.

konst/__init__.py

@@ -2,14 +2,12 @@
 from __future__ import absolute_import
 
 from django.utils.deconstruct import deconstructible
-from django.utils.encoding import python_2_unicode_compatible
 
 # https://code.djangoproject.com/wiki/CookBookChoicesContantsClass
 # modified to work with translation plus fields
 
 
 @deconstructible
-@python_2_unicode_compatible
 class Constant(object):
     def __init__(self, label=None, **kwargs):
         self.constants = None

konst/extras/drf/fields.py

@@ -1,7 +1,6 @@
 # -*- coding: utf-8 -*-
 from __future__ import absolute_import
 
-from django.utils import six
 from django.utils.translation import ugettext_lazy as _
 
 from rest_framework.fields import Field
@@ -26,7 +25,7 @@ def to_internal_value(self, data):
         if data == "" and self.allow_blank:
             return ""
         try:
-            return self.constants.by_id[six.text_type(data)]
+            return self.constants.by_id[str(data)]
         except KeyError:
             self.fail("invalid_choice", input=data)
 

konst/models/fields.py

@@ -27,7 +27,7 @@ def get_prep_value(self, value):
             return value.v
         return value
 
-    def from_db_value(self, value, expression, connection, *args):
+    def from_db_value(self, value, expression, connection):
         # print "from_db_value: {}: {}".format(type(value), value)
         if value is None:
             return value

setup.py

@@ -11,7 +11,7 @@
 with open("README.md", "r") as fh:
     long_description = fh.read()
 
-tests_require = ["pytest", "pytest-django", "djangorestframework>=3.4.7"]
+tests_require = ["pytest", "pytest-django", "djangorestframework>=3.10"]
 
 setup(
     name=name,
@@ -20,7 +20,7 @@
     description=description,
     long_description=long_description,
     long_description_content_type="text/markdown",
-    version="1.0.2",
+    version="2.0.0",
     license="MIT",
     url=url,
     packages=find_packages(),
@@ -31,11 +31,14 @@
         "License :: OSI Approved :: BSD License",
         "Operating System :: OS Independent",
         "Programming Language :: Python",
-        "Programming Language :: Python :: 2",
         "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.5",
+        "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
         "Framework :: Django",
     ],
-    install_requires=["django>=1.8"],
+    install_requires=["django>=2.2"],
     test_suite="runtests.runtests",
     tests_require=tests_require,
     zip_safe=False,