Set history delete_related to False by default

This is a breaking change. The default behavior is to delete the
related objects, but it doesn't make sense to apply it to audit log
entries, at least not by default.

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 - feat: Change `LogEntry.change` field type to `JSONField` rather than `TextField`. This change include a migration that may take time to run depending on the number of records on your `LogEntry` table ([#407](https://github.com/jazzband/django-auditlog/pull/407))([#495](https://github.com/jazzband/django-auditlog/pull/495))
 - Python: Drop support for Python 3.7 ([#546](https://github.com/jazzband/django-auditlog/pull/546))
+- feat: Set `AuditlogHistoryField.delete_related` to `False` by default. This is different from the default configuration of Django's `GenericRelation`, but we should not erase the audit log of objects on deletion by default. ([#557](https://github.com/jazzband/django-auditlog/pull/557))
 
 #### Improvements
 

auditlog/models.py

@@ -557,14 +557,12 @@ class AuditlogHistoryField(GenericRelation):
 
     :param pk_indexable: Whether the primary key for this model is not an :py:class:`int` or :py:class:`long`.
     :type pk_indexable: bool
-    :param delete_related: By default, including a generic relation into a model will cause all related
-        objects to be cascade-deleted when the parent object is deleted. Passing False to this overrides this
-        behavior, retaining the full auditlog history for the object. Defaults to True, because that's
-        Django's default behavior.
+    :param delete_related: Delete referenced auditlog entries together with the tracked object.
+        Defaults to False to keep the integrity of the auditlog.
     :type delete_related: bool
     """
 
-    def __init__(self, pk_indexable=True, delete_related=True, **kwargs):
+    def __init__(self, pk_indexable=True, delete_related=False, **kwargs):
         kwargs["to"] = LogEntry
 
         if pk_indexable:

auditlog_tests/models.py

@@ -21,7 +21,7 @@ class SimpleModel(models.Model):
     integer = models.IntegerField(blank=True, null=True)
     datetime = models.DateTimeField(auto_now=True)
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
     def __str__(self):
         return self.text
@@ -39,7 +39,7 @@ class AltPrimaryKeyModel(models.Model):
     integer = models.IntegerField(blank=True, null=True)
     datetime = models.DateTimeField(auto_now=True)
 
-    history = AuditlogHistoryField(pk_indexable=False)
+    history = AuditlogHistoryField(delete_related=True, pk_indexable=False)
 
 
 class UUIDPrimaryKeyModel(models.Model):
@@ -54,7 +54,7 @@ class UUIDPrimaryKeyModel(models.Model):
     integer = models.IntegerField(blank=True, null=True)
     datetime = models.DateTimeField(auto_now=True)
 
-    history = AuditlogHistoryField(pk_indexable=False)
+    history = AuditlogHistoryField(delete_related=True, pk_indexable=False)
 
 
 class ProxyModel(SimpleModel):
@@ -84,7 +84,7 @@ class RelatedModel(RelatedModelParent):
         to="SimpleModel", on_delete=models.CASCADE, related_name="reverse_one_to_one"
     )
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
 
 class ManyRelatedModel(models.Model):
@@ -95,7 +95,7 @@ class ManyRelatedModel(models.Model):
     recursive = models.ManyToManyField("self")
     related = models.ManyToManyField("ManyRelatedOtherModel", related_name="related")
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
     def get_additional_data(self):
         related = self.related.first()
@@ -107,7 +107,7 @@ class ManyRelatedOtherModel(models.Model):
     A model related to ManyRelatedModel as many-to-many.
     """
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
 
 @auditlog.register(include_fields=["label"])
@@ -119,7 +119,7 @@ class SimpleIncludeModel(models.Model):
     label = models.CharField(max_length=100)
     text = models.TextField(blank=True)
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
 
 class SimpleExcludeModel(models.Model):
@@ -130,7 +130,7 @@ class SimpleExcludeModel(models.Model):
     label = models.CharField(max_length=100)
     text = models.TextField(blank=True)
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
 
 class SimpleMappingModel(models.Model):
@@ -142,7 +142,7 @@ class SimpleMappingModel(models.Model):
     vtxt = models.CharField(verbose_name="Version", max_length=100)
     not_mapped = models.CharField(max_length=100)
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
 
 @auditlog.register(mask_fields=["address"])
@@ -154,7 +154,7 @@ class SimpleMaskedModel(models.Model):
     address = models.CharField(max_length=100)
     text = models.TextField()
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
 
 class AdditionalDataIncludedModel(models.Model):
@@ -167,7 +167,7 @@ class AdditionalDataIncludedModel(models.Model):
     text = models.TextField(blank=True)
     related = models.ForeignKey(to=SimpleModel, on_delete=models.CASCADE)
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
     def get_additional_data(self):
         """
@@ -194,7 +194,7 @@ class DateTimeFieldModel(models.Model):
     time = models.TimeField()
     naive_dt = models.DateTimeField(null=True, blank=True)
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
 
 class ChoicesFieldModel(models.Model):
@@ -216,7 +216,7 @@ class ChoicesFieldModel(models.Model):
     status = models.CharField(max_length=1, choices=STATUS_CHOICES)
     multiplechoice = models.CharField(max_length=255, choices=STATUS_CHOICES)
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
 
 class CharfieldTextfieldModel(models.Model):
@@ -229,7 +229,7 @@ class CharfieldTextfieldModel(models.Model):
     longchar = models.CharField(max_length=255)
     longtextfield = models.TextField()
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
 
 class PostgresArrayFieldModel(models.Model):
@@ -251,7 +251,7 @@ class PostgresArrayFieldModel(models.Model):
         models.CharField(max_length=1, choices=STATUS_CHOICES), size=3
     )
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
 
 class NoDeleteHistoryModel(models.Model):
@@ -314,7 +314,7 @@ class SimpleNonManagedModel(models.Model):
     integer = models.IntegerField(blank=True, null=True)
     datetime = models.DateTimeField(auto_now=True)
 
-    history = AuditlogHistoryField()
+    history = AuditlogHistoryField(delete_related=True)
 
     def __str__(self):
         return self.text