Fixed error when trying to get instance if object is deleted #571 (#574)

* Fixed error when trying to get instance if object is deleted #571

* fixed DoesNotExist bug #571 and updated tests

* updated CHANGES.rst

* updated AUTHORS.rst

* Don't pass excluded fields to instance if object is deleted.
Rewrited tests

Author: yakimka

AUTHORS.rst

@@ -87,6 +87,7 @@ Authors
 - Trey Hunner (`treyhunner <https://github.com/treyhunner>`_)
 - Ulysses Vilela
 - `vnagendra <https://github.com/vnagendra>`_
+- `yakimka <https://github.com/yakimka>`_
 
 Background
 ==========

CHANGES.rst

@@ -1,6 +1,10 @@
 Changes
 =======
 
+Unreleased
+----------
+- Fixed DoesNotExist error when trying to get instance if object is deleted (gh-571)
+
 2.7.3 (2019-07-15)
 ------------------
 - Fixed BigAutoField not mirrored as BigInt (gh-556)

simple_history/models.py

@@ -11,6 +11,7 @@
 from django.conf import settings
 from django.contrib import admin
 from django.contrib.auth import get_user_model
+from django.core.exceptions import ObjectDoesNotExist
 from django.core.serializers import serialize
 from django.db import models
 from django.db.models import Q
@@ -378,12 +379,16 @@ def get_instance(self):
                     model._meta.get_field(field).attname
                     for field in self._history_excluded_fields
                 ]
-                values = (
-                    model.objects.filter(pk=getattr(self, model._meta.pk.attname))
-                    .values(*excluded_attnames)
-                    .get()
-                )
-                attrs.update(values)
+                try:
+                    values = (
+                        model.objects.filter(pk=getattr(self, model._meta.pk.attname))
+                        .values(*excluded_attnames)
+                        .get()
+                    )
+                except ObjectDoesNotExist:
+                    pass
+                else:
+                    attrs.update(values)
             return model(**attrs)
 
         def get_next_record(self):

simple_history/tests/models.py

@@ -1,5 +1,6 @@
 from __future__ import unicode_literals
 
+import datetime
 import uuid
 from django.apps import apps
 from django.conf import settings
@@ -35,6 +36,25 @@ class PollWithExcludeFields(models.Model):
     history = HistoricalRecords(excluded_fields=["pub_date"])
 
 
+class PollWithExcludedFieldsWithDefaults(models.Model):
+    question = models.CharField(max_length=200)
+    pub_date = models.DateTimeField("date published")
+    expiration_time = models.DateField(default=datetime.date(2030, 12, 12))
+    place = models.TextField(null=True)
+    min_questions = models.PositiveIntegerField(default=1)
+    max_questions = models.PositiveIntegerField()
+
+    history = HistoricalRecords(
+        excluded_fields=[
+            "pub_date",
+            "expiration_time",
+            "place",
+            "min_questions",
+            "max_questions",
+        ]
+    )
+
+
 class PollWithExcludedFKField(models.Model):
     question = models.CharField(max_length=200)
     pub_date = models.DateTimeField("date published")

simple_history/tests/tests/test_models.py

@@ -75,6 +75,7 @@
     Poll,
     PollInfo,
     PollWithExcludeFields,
+    PollWithExcludedFieldsWithDefaults,
     PollWithExcludedFKField,
     PollWithHistoricalIPAddress,
     Province,
@@ -1186,6 +1187,29 @@ def test_restore_pollwithexclude(self):
         self.assertEqual(original.pub_date, poll.pub_date)
 
 
+class ExcludeFieldsForDeletedObjectTest(TestCase):
+    def setUp(self):
+        self.poll = PollWithExcludedFieldsWithDefaults.objects.create(
+            question="what's up?", pub_date=today, max_questions=12
+        )
+        self.historical = self.poll.history.order_by("pk")[0]
+        self.poll.delete()
+
+    def test_restore_deleted_poll_exclude_fields(self):
+        original = self.historical.instance
+        # pub_date don't have default value so it will be None
+        self.assertIsNone(original.pub_date)
+        # same for max_questions
+        self.assertIsNone(original.max_questions)
+
+    def test_restore_deleted_poll_exclude_fields_with_defaults(self):
+        poll = self.poll
+        original = self.historical.instance
+        self.assertEqual(original.expiration_time, poll.expiration_time)
+        self.assertEqual(original.place, poll.place)
+        self.assertEqual(original.min_questions, poll.min_questions)
+
+
 class ExcludeForeignKeyTest(TestCase):
     def setUp(self):
         self.poll = PollWithExcludedFKField.objects.create(