✨ Fixes #103 -- support natural keys for the models

Added support for natural keys for the cookie and cookie group
models. This required adding another unique constraint, this
time to the cookie model. A specific cookie within a group was
already looked up by name and domain in the existing code, so
this DB constraint confirms the usage. Duplicate data would not
have yielded the expected results, but users may not be aware
of it, so this is also a breaking change.

You can now dump and load fixtures for cookie consent, using
these natural keys and avoid database primary key conflicts.

cookie_consent/migrations/0004_cookie_natural_key.py

@@ -0,0 +1,19 @@
+# Generated by Django 4.2.13 on 2024-05-09 20:22
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("cookie_consent", "0003_alter_cookiegroup_varname"),
+    ]
+
+    operations = [
+        migrations.AddConstraint(
+            model_name="cookie",
+            constraint=models.UniqueConstraint(
+                fields=("cookiegroup", "name", "domain"), name="natural_key"
+            ),
+        ),
+    ]

cookie_consent/models.py

@@ -48,6 +48,11 @@ def update(self, **kwargs):
         return super().update(**kwargs)
 
 
+class CookieGroupManager(models.Manager.from_queryset(BaseQueryset)):
+    def get_by_natural_key(self, varname):
+        return self.get(varname=varname)
+
+
 class CookieGroup(models.Model):
     varname = models.CharField(
         _("Variable name"),
@@ -70,7 +75,7 @@ class CookieGroup(models.Model):
     ordering = models.IntegerField(_("Ordering"), default=0)
     created = models.DateTimeField(_("Created"), auto_now_add=True, blank=True)
 
-    objects = BaseQueryset.as_manager()
+    objects = CookieGroupManager()
 
     class Meta:
         verbose_name = _("Cookie Group")
@@ -88,6 +93,9 @@ def save(self, *args, **kwargs):
     def delete(self, *args, **kwargs):
         return super().delete(*args, **kwargs)
 
+    def natural_key(self):
+        return (self.varname,)
+
     def get_version(self) -> str:
         try:
             return str(self.cookie_set.all()[0].get_version())
@@ -104,6 +112,12 @@ def for_json(self) -> CookieGroupDict:
         }
 
 
+class CookieManager(models.Manager.from_queryset(BaseQueryset)):
+    def get_by_natural_key(self, name, domain, cookiegroup):
+        group = CookieGroup.objects.get_by_natural_key(cookiegroup)
+        return self.get(cookiegroup=group, name=name, domain=domain)
+
+
 class Cookie(models.Model):
     cookiegroup = models.ForeignKey(
         CookieGroup,
@@ -116,11 +130,17 @@ class Cookie(models.Model):
     domain = models.CharField(_("Domain"), max_length=250, blank=True)
     created = models.DateTimeField(_("Created"), auto_now_add=True, blank=True)
 
-    objects = BaseQueryset.as_manager()
+    objects = CookieManager()
 
     class Meta:
         verbose_name = _("Cookie")
         verbose_name_plural = _("Cookies")
+        constraints = [
+            models.UniqueConstraint(
+                fields=("cookiegroup", "name", "domain"),
+                name="natural_key",
+            ),
+        ]
         ordering = ["-created"]
 
     def __str__(self):
@@ -134,6 +154,11 @@ def save(self, *args, **kwargs):
     def delete(self, *args, **kwargs):
         return super().delete(*args, **kwargs)
 
+    def natural_key(self):
+        return (self.name, self.domain) + self.cookiegroup.natural_key()
+
+    natural_key.dependencies = ["cookie_consent.cookiegroup"]
+
     @property
     def varname(self):
         return "%s=%s:%s" % (self.cookiegroup.varname, self.name, self.domain)

docs/changelog.rst

@@ -6,8 +6,9 @@ Changelog
 ------------------
 
 💥 This feature release has a potential breaking change. The ``CookieGroup.varname``
-field now has a unique constraint on it. If you have duplicate values, this migration
-will crash.
+field now has a unique constraint on it. The ``Cookie`` model now has a unique
+constraint on ``cookiegroup``, ``name`` and ``domain``. If you have duplicate values,
+this migration will crash.
 
 * ...
 

tests/test_cookie_group_model.py

@@ -0,0 +1,19 @@
+import pytest
+
+from cookie_consent.models import CookieGroup
+
+
+def test_natural_key():
+    group = CookieGroup(varname="social")
+
+    assert group.natural_key() == ("social",)
+
+
+@pytest.mark.django_db
+def test_load_by_natural_key():
+    social_group = CookieGroup.objects.create(varname="social")
+    CookieGroup.objects.create(varname="other")
+
+    loaded_group = CookieGroup.objects.get_by_natural_key("social")
+
+    assert loaded_group == social_group

tests/test_cookie_model.py

@@ -0,0 +1,24 @@
+import pytest
+
+from cookie_consent.models import Cookie, CookieGroup
+
+
+def test_natural_key():
+    cookie = Cookie(
+        cookiegroup=CookieGroup(varname="analytics"), name="trck", domain="example.com"
+    )
+
+    assert cookie.natural_key() == ("trck", "example.com", "analytics")
+
+
+@pytest.mark.django_db
+def test_load_by_natural_key():
+    social_group = CookieGroup.objects.create(varname="social")
+    cookie = Cookie.objects.create(
+        cookiegroup=social_group, name="trck", domain="example.com"
+    )
+    Cookie.objects.create(cookiegroup=social_group, name="other", domain="example.com")
+
+    loaded_cookie = Cookie.objects.get_by_natural_key("trck", "example.com", "social")
+
+    assert loaded_cookie == cookie

tests/test_models.py

@@ -1,6 +1,5 @@
 # -*- coding: utf-8 -*-
 from copy import deepcopy
-from unittest import mock
 
 from django.conf import settings
 from django.core.cache import caches