Refactor base classes

.github/workflows/tox.yml

@@ -38,8 +38,8 @@ jobs:
 
     strategy:
       matrix:
-        python: ["3.10", "3.11"]
-        django: ["32", "40", "41", "42", "main"]
+        python: ["3.11"]
+        django: ["32", "40", "41", "42", "50", "main"]
 
     env:
       TOXENV: py${{ matrix.python }}-django${{ matrix.django }}

README.md

@@ -25,6 +25,30 @@ up-to-date.
 The anonymisation itself doesn't change - it's just shifting the code
 around.
 
+## Redaction vs. Anonymisation
+
+This library contains two flavours of anonymisation - Redaction, and
+Anonymisation. The two differ in how the data is overwritten:
+
+Type | Implementation | Performance | Data
+--- | --- | --- | ---
+Redaction | SQL | Fast | Table level
+Anonymisation | Python | Slow | Row level
+
+### Redaction
+
+Redaction is implemented as a single SQL `update` statement that wipes
+an entire table in one go. It's very fast, but it's limited in the sense
+that it cannot produce realistic data. In fact it may well render your
+application unusable. It is recommended as the first step in data
+anonymisation.
+
+### Anonymisation
+
+Anonymisation is an row-level operation that iterates over a
+queryset and updates each object in turn. The main advantage is that
+post-anonymisation you will have realistic, usable, data.
+
 ## Usage
 
 As an example - this is a hypothetical User model's anonymisation today:
@@ -42,7 +66,7 @@ a new anonymiser that splits out each field:
 ```python
 # anonymisers.py
 @register_anonymiser
-class UserAnonymiser(BaseAnonymiser):
+class UserAnonymiser(ModelAnonymiser):
     model = User
 
     def anonymise_first_name(self, obj: User) -> None:

anonymiser/decorators.py

@@ -1,8 +1,8 @@
-from .models import BaseAnonymiser
-from .registry import register
+from .models import ModelAnonymiser
+from .registry import register_model_anonymiser
 
 
-def register_anonymiser(anonymiser: type[BaseAnonymiser]) -> type[BaseAnonymiser]:
+def register_anonymiser(anonymiser: type[ModelAnonymiser]) -> type[ModelAnonymiser]:
     """Add {model: Anonymiser} to the global registry."""
-    register(anonymiser)
+    register_model_anonymiser(anonymiser)
     return anonymiser

anonymiser/management/commands/display_model_anonymisation.py

@@ -1,46 +1,16 @@
 from typing import Any
 
-from django.apps import apps
 from django.core.management.base import BaseCommand
-from django.db.models import ForeignObjectRel, Model
 from django.template.loader import render_to_string
 
-from anonymiser.models import FieldSummaryData
-from anonymiser.registry import get_model_anonymiser
+from anonymiser import registry
 
 
 class Command(BaseCommand):
-    def get_models(self) -> list[type[Model]]:
-        """Force alphabetical order of models."""
-        return sorted(apps.get_models(), key=lambda m: m._meta.label)
-
-    def get_fields(self, model: type[Model]) -> list:
-        """Get model fields ordered by type and then name."""
-        return sorted(
-            [
-                f
-                for f in model._meta.get_fields()
-                if not isinstance(f, ForeignObjectRel)
-            ],
-            key=lambda f: f.__class__.__name__ + f.name,
-        )
-
     def handle(self, *args: Any, **options: Any) -> None:
-        model_fields: list[FieldSummaryData] = []
-        model_anonymisers: dict[str, str] = {}
-        for model in self.get_models():
-            model_name = model._meta.label
-            anonymiser = get_model_anonymiser(model)
-            anonymiser_name = anonymiser.__class__.__name__ if anonymiser else ""
-            model_anonymisers[model_name] = anonymiser_name
-            for f in self.get_fields(model):
-                is_anonymisable = False
-                if anonymiser:
-                    is_anonymisable = anonymiser.is_field_anonymisable(f.name)
-                field_data = FieldSummaryData(f, is_anonymisable)
-                model_fields.append(field_data)
+        model_fields = registry.get_all_model_fields()
         out = render_to_string(
             "display_model_anonymisation.md",
-            {"model_anonymisers": model_anonymisers, "model_fields": model_fields},
+            {"model_fields": model_fields},
         )
         self.stdout.write(out)