change model: discarded_by instead of deletes_change and reset updates

src/c3nav/editor/migrations/0004_auto_20170620_0934.py

@@ -0,0 +1,35 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.2 on 2017-06-20 09:34
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('editor', '0003_auto_20170618_1942'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='change',
+            name='deletes_change',
+        ),
+        migrations.AddField(
+            model_name='change',
+            name='discarded_by',
+            field=models.OneToOneField(null=True, on_delete=django.db.models.deletion.CASCADE, related_name='discards', to='editor.Change', verbose_name='discarded by other change'),
+        ),
+        migrations.AlterField(
+            model_name='change',
+            name='action',
+            field=models.CharField(choices=[('create', 'create object'), ('delete', 'delete object'), ('update', 'update attribute'), ('m2m_add', 'add many to many relation'), ('m2m_remove', 'add many to many relation')], max_length=16, verbose_name='action'),
+        ),
+        migrations.AlterField(
+            model_name='change',
+            name='model_name',
+            field=models.CharField(max_length=50, verbose_name='model name'),
+        ),
+    ]

src/c3nav/editor/models.py

@@ -4,7 +4,6 @@ from collections import OrderedDict
 
 from django.apps import apps
 from django.conf import settings
-from django.core.exceptions import ObjectDoesNotExist, ValidationError
 from django.db import models
 from django.db.models import Q
 from django.db.models.fields.related_descriptors import ForwardManyToOneDescriptor, ManyToManyDescriptor
@@ -87,11 +86,17 @@ class ChangeSet(models.Model):
 
         if change.existing_object_pk is None:
             if change.action == 'update':
-                self.created_objects[model][change.created_object_id][name] = value
+                if value is None:
+                    self.created_objects[model][change.created_object_id].pop(name)
+                else:
+                    self.created_objects[model][change.created_object_id][name] = value
             return
 
         if change.action == 'update':
-            self.updated_existing.setdefault(model, {}).setdefault(pk, {})[name] = value
+            if value is None:
+                self.updated_existing.setdefault(model, {}).setdefault(pk, {}).pop(name)
+            else:
+                self.updated_existing.setdefault(model, {}).setdefault(pk, {})[name] = value
 
     def get_changed_values(self, model, name):
         r = tuple((pk, values[name]) for pk, values in self.updated_existing.get(model, {}).items() if name in values)
@@ -305,7 +310,6 @@ class ChangeSet(models.Model):
 
 class Change(models.Model):
     ACTIONS = (
-        ('delchange', _('delete change')),
         ('create', _('create object')),
         ('delete', _('delete object')),
         ('update', _('update attribute')),
@@ -316,9 +320,9 @@ class Change(models.Model):
     author = models.ForeignKey(settings.AUTH_USER_MODEL, null=True, on_delete=models.PROTECT, verbose_name=_('Author'))
     created = models.DateTimeField(auto_now_add=True, verbose_name=_('created'))
     action = models.CharField(max_length=16, choices=ACTIONS, verbose_name=_('action'))
-    deletes_change = models.OneToOneField('Change', null=True, on_delete=models.CASCADE, related_name='deleted_by',
+    discarded_by = models.OneToOneField('Change', null=True, on_delete=models.CASCADE, related_name='discards',
-                                          verbose_name=_('deletes change'))
+                                        verbose_name=_('discarded by other change'))
-    model_name = models.CharField(max_length=50, null=True, verbose_name=_('model name'))
+    model_name = models.CharField(max_length=50, verbose_name=_('model name'))
     existing_object_pk = models.PositiveIntegerField(null=True, verbose_name=_('id of existing object'))
     created_object = models.ForeignKey('Change', null=True, on_delete=models.CASCADE, related_name='changed_by',
                                        verbose_name=_('changed object'))
@@ -409,41 +413,9 @@ class Change(models.Model):
         self.created_object = None
         self._set_object = value
 
-    def clean(self):
-        if self.action == 'delchange':
-            if self.deletes_change is None:
-                raise ValidationError('deletes_change has to be set if action is delchange.')
-            if self.deletes_change.changeset_id != self.changeset_id:
-                raise ValidationError('deletes_change refers to a change from a different changeset.')
-
-            for field_name in ('model_name', 'existing_object_pk', 'created_object', 'field_name', 'field_value'):
-                if getattr(self, field_name) is not None:
-                    raise ValidationError('%s must not be set if action is delchange.' % field_name)
-            return
-
-        if self.deletes_change is not None:
-            raise ValidationError('deletes_change can only be set if action is delchange.')
-
-        if self.model_name is None:
-            raise ValidationError('model_name has to be set if action is not delchange.')
-
-        try:
-            # noinspection PyUnusedLocal
-            tmp = self.model_class if self.action == 'create' else self.obj  # noqa
-        except TypeError as e:
-            raise ValidationError(str(e))
-        except ObjectDoesNotExist:
-            raise ValidationError('existing object does not exist.')
-
-        if self.action in ('create', 'delete'):
-            for field_name in ('field_name', 'field_value'):
-                if getattr(self, field_name) is not None:
-                    raise ValidationError('%s must not be set if action is create or delete.' % field_name)
-
     def save(self, *args, **kwargs):
-        self.clean()
         if self.pk is not None:
-            raise TypeError('change objects can not be edited.')
+            raise TypeError('change objects can not be edited (use update to set discarded_by)')
         if self.changeset.proposed is not None or self.changeset.applied is not None:
             raise TypeError('can not add change object to uneditable changeset.')
         super().save(*args, **kwargs)