Added possibility for creating GenericRelations with UUID Fields

README.rst

@@ -106,3 +106,100 @@ Known problems
 Do **not** use any of the following names in your models: ``created_at``, ``created_by``, ``change_sets``,
 ``last_modified_by``, ``last_modified_at``, ``changed_data``
 
+
+Generic Relations
+-----------------
+
+It is possible to use Django Changeset with Djangos ``GenericRelation`` like this (tested with Django 1.11):
+
+.. code-block:: python
+
+    class MyModel(models.Model, RevisionModelMixin):
+        ...
+
+        changesets = GenericRelation(
+            ChangeSet,
+            content_type_field='object_type',
+            object_id_field='object_uuid'
+        )
+
+
+This allows the Django ORM to use queries on changeset (e.g., on the changeset type INSERT):
+
+.. code-block:: python
+
+    MyModel.objects.filter(changesets__changeset_type='I')
+
+
+
+Generic Relations with UUID
+---------------------------
+
+The query from above does not work in Postgres when using the built-in ``UUID`` datatype, e.g.:
+
+.. code-block:: python
+
+    class MyModel(models.Model, RevisionModelMixin):
+        my_pk = models.UUIDField(primary_key=True, editable=False, default=uuid.uuid4)
+
+        ...
+
+        changesets = GenericRelation(
+            ChangeSet,
+            content_type_field='object_type',
+            object_id_field='object_uuid'
+        )
+
+
+This is due to the fact that the ``ChangeSet`` model uses a ``CharField(max_length=...)`` for the ``object_uuid``.
+It is possible to change this behaviour by using ``DJANGO_CHANGESET_PK_TYPE = "UUID"`` in your Django settings file.
+This will convert swap out the basic ``object_uuid`` field from:
+
+.. code-block:: python
+
+    object_uuid = models.CharField(
+        verbose_name=_(u"Object UUID"),
+        max_length=255,
+        editable=False,
+    )
+
+to this:
+
+.. code-block:: python
+
+    object_uuid = models.UUIDField(
+        verbose_name=_(u"Object UUID"),
+        editable=False,
+    )
+
+
+This obviously **requires** a migration! Do **not** run the ``makemigrations`` command to do this. Instead, add a
+migration file manually to **your application** (e.g., ``your_app``), which will look something like this:
+
+.. code-block:: python
+
+    # -*- coding: utf-8 -*-
+    # Generated by Django 1.11.2 on 2017-06-30 08:22
+    from __future__ import unicode_literals
+
+    from django.db import migrations, models
+
+
+    class Migration(migrations.Migration):
+        dependencies = [
+            ('django_changeset', '0002_add_index_changesettype'),
+            ('your_app', '0815_your_last_migration')
+        ]
+
+        operations = [
+            migrations.AlterField(
+                model_name='changeset',
+                name='object_uuid',
+                field=models.UUIDField(editable=False, verbose_name='Object UUID'),
+            ),
+        ]
+
+        def __init__(self, name, app_label):
+            super(Migration, self).__init__(name, 'django_changeset')
+
+

django_changeset/models/models.py

@@ -5,6 +5,8 @@
 
 from django.db import models
 from django.contrib.contenttypes.models import ContentType
+from django.contrib.contenttypes.fields import GenericForeignKey
+
 from django.utils.translation import ugettext_lazy as _
 from django.utils.encoding import force_text
 
@@ -13,7 +15,7 @@
 logger = logging.getLogger(__name__)
 
 
-class ChangeSet(models.Model):
+class AbstractChangeSet(models.Model):
     """ Basic changeset/revision model which contains the ``user`` that modified the object ``object_type`` """
 
     # choices for changeset type (insert, update, delete)
@@ -65,16 +67,17 @@ class ChangeSet(models.Model):
         null=False,
     )
 
-    object_uuid = models.CharField(
-        verbose_name=_(u"Object UUID"),
-        max_length=255,
-        editable=False,
-    )
+    # object_uuid = models.CharField(
+    #     verbose_name=_(u"Object UUID"),
+    #     max_length=255,
+    #     editable=False,
+    # )
 
     class Meta:
         app_label = 'django_changeset'
         get_latest_by = 'date'
         ordering = ['-date', ]
+        abstract = True
 
     def __unicode__(self):
         return _(u"%(changeset_type)s on %(app_label)s.%(model)s %(uuid)s at date %(date)s by %(user)s") % {
@@ -89,6 +92,23 @@ def __unicode__(self):
     def __str__(self):
         return self.__unicode__()
 
+from django.conf import settings
+
+
+if hasattr(settings, "DJANGO_CHANGESET_PK_TYPE") and settings.DJANGO_CHANGESET_PK_TYPE == 'UUID':
+    class ChangeSet(AbstractChangeSet):
+        object_uuid = models.UUIDField(
+            verbose_name=_(u"Object UUID"),
+            editable=False,
+        )
+else:
+    class ChangeSet(AbstractChangeSet):
+        object_uuid = models.CharField(
+            verbose_name=_(u"Object UUID"),
+            max_length=255,
+            editable=False,
+        )
+
 
 class ChangeRecord(models.Model):
     """ A change_record represents detailed change information, like which field was changed and what the old aswell as

setup.py

@@ -10,7 +10,7 @@
 
 setup(
     name='django-changeset',
-    version='0.6.2',
+    version='0.7.0',
     packages=find_packages(),
     include_package_data=True,
     license='BSD License',