Add hashing on TrackedModel user-editable content.

common/business_rules.py

@@ -11,7 +11,6 @@
 from typing import Iterator
 from typing import Mapping
 from typing import Optional
-from typing import Set
 from typing import Type
 from typing import Union
 
@@ -57,7 +56,7 @@ def __init__(self, model: TrackedModel, message: Optional[str] = None):
         super().__init__(message, model)
 
 
-ALL_RULES: Set[Type[BusinessRule]] = set()
+ALL_RULES: Dict[str, Type[BusinessRule]] = {}
 
 
 class BusinessRuleBase(type):
@@ -106,7 +105,10 @@ def __new__(cls, name, bases, attrs, **kwargs):
             getattr(new_class, "__doc__", None),
         )
 
-        ALL_RULES.add(new_class)
+        assert (
+            name not in ALL_RULES
+        ), f"Business Rules Must Have Unique Names: {new_class} == {ALL_RULES[name]}"
+        ALL_RULES[name] = new_class
 
         return new_class
 

common/models/tracked_qs.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from hashlib import sha256
 from typing import List
 
 from django.db.models import Case
@@ -350,3 +351,12 @@ def follow_path(self, path: str) -> TrackedModelQuerySet:
                 qs = model_type.objects.none()
 
         return qs.distinct()
+
+    def content_hash(self):
+        """
+        :return: Combined sha256 hash for all contained TrackedModels.
+        """
+        sha = sha256()
+        for o in self:
+            sha.update(o.content_hash())
+        return sha.digest()

common/models/trackedmodel.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from hashlib import sha256
+from json import dumps
 from typing import Any
 from typing import Dict
 from typing import Iterable
@@ -658,3 +660,22 @@ def get_url_pattern_name_prefix(cls):
         if not prefix:
             prefix = cls._meta.verbose_name.replace(" ", "_")
         return prefix
+
+    def content_hash(self):
+        """
+        Hash of the user editable content, used by business rule checks for
+        result caching.
+
+        :return: 32 character sha256 'digest', see hashlib.sha256.
+        """
+        content = {
+            field.name: str(getattr(self, field.name)) for field in self.copyable_fields
+        }
+
+        # The json encoder ensures a somewhat regular format and everything
+        # passed to it must be hashable.
+        hashable = dumps(content).encode("utf-8")
+
+        sha = sha256()
+        sha.update(hashable)
+        return sha.digest()

pii-ner-exclude.txt

@@ -1148,3 +1148,5 @@ self.linked_model
 WorkBasketOutputFormat
 param kwargs:
 Enum
+sha256
+hashlib.sha256