feat(core): Dynamic History model creation

ref: #765 #758 #759

app/core/models/audit.py

@@ -143,7 +143,8 @@ class ModelHistory(
         TenancyObject (_type_): Centurion Tenancy Abstract model.
     """
 
-    audit_enabled: bool = False
+    _audit_enabled: bool = False
+    """Don't Save audit history for audit history model"""
 
 
     class Meta:

app/core/models/centurion.py

@@ -11,6 +11,13 @@ class CenturionModel(
 
 
 
+    _audit_enabled: bool = True
+    """Should this model have audit history kept"""
+
+    _is_submodel: bool = False
+    """This model a sub-model"""
+
+
     class Meta:
 
         abstract = True
@@ -22,3 +29,27 @@ class CenturionModel(
         if value is None:
 
             raise ValidationError(code = 'field_value_not_none', message = 'Value can not be none.')
+
+
+
+    def get_history_model_name(self) -> str:
+        """Get the name for the History Model
+
+        Returns:
+            str: Name of the history model (`<model class name>AuditHistory`)
+        """
+        
+        return f'{self._meta.object_name}AuditHistory'
+
+
+class CenturionSubModel(
+    CenturionModel
+):
+
+    _is_submodel: bool = True
+    """This model a sub-model"""
+
+
+    class Meta:
+
+        abstract = True

app/core/models/meta.py

@@ -0,0 +1,62 @@
+import sys
+import types
+
+from django.apps import apps
+from django.db import models
+from django.utils.module_loading import import_string
+
+
+
+module_path = f'centurion.models.meta'
+
+if module_path not in sys.modules:
+
+    sys.modules[module_path] = types.ModuleType(module_path)
+
+
+if any(cmd in sys.argv for cmd in ['runserver', 'makemigrations', 'migrate']):
+
+    if apps.models_ready:
+
+        existing_models = { m.__name__ for m in apps.get_models() }
+
+        for model in apps.get_models():
+
+            if not getattr(model, '_audit_enabled', False):
+                continue
+
+            name = model.__name__
+
+            audit_meta_name = model().get_history_model_name()
+
+            if audit_meta_name in existing_models:
+                continue
+
+
+            AuditMetaModel = type(
+                audit_meta_name,
+                ( import_string("core.models.audit.AuditMetaModel"), ),
+                {
+                    '__module__': module_path,
+                    '__qualname__': audit_meta_name,
+                    '__doc__': f'Auto-generated meta model for {name} Audit History.',
+                    'Meta': type('Meta', (), {
+                                'app_label': model._meta.app_label,
+                                'db_table': model._meta.db_table + '_history',
+                                'managed': True,
+                                'verbose_name': model._meta.verbose_name + ' History',
+                                'verbose_name_plural': model._meta.verbose_name + ' Histories',
+                            }),
+                    'model': models.ForeignKey(
+                        model,
+                        blank = False,
+                        help_text = 'Model this history belongs to',
+                        null = False,
+                        on_delete = models.CASCADE,
+                        related_name = 'audit_history',
+                        verbose_name = 'Model',
+                    )
+                }
+            )
+
+            setattr(sys.modules[module_path], audit_meta_name, AuditMetaModel)