validate changes and add button to restore them

src/c3nav/editor/models/change.py

@@ -4,11 +4,12 @@ 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 import Q, FieldDoesNotExist
 from django.utils.translation import ugettext_lazy as _
 
-from c3nav.editor.utils import is_created_pk
+from c3nav.editor.utils import is_created_pk, get_current_obj
 from c3nav.editor.wrappers import ModelInstanceWrapper
 
 
@@ -131,6 +132,91 @@ class Change(models.Model):
     def field(self):
         return self.model_class._meta.get_field(self.field_name)
 
+    def check_apply_problem(self):
+        if self.discarded_by_id is not None or self.action in ('create', 'restore'):
+            return None
+
+        try:
+            model = self.model_class
+        except LookupError:
+            return _('Type %(model_name)s does not exist any more.' % {'model_name': self.model_name})
+
+        try:
+            obj = get_current_obj(model, self.obj_pk)
+        except model.DoesNotExist:
+            return _('This %(model_title)s does not exist any more.' % {'model_title': model._meta.verbose_name})
+
+        if self.action == 'delete':
+            return None
+
+        if self.action == 'update' and self.field_name.startswith('title_'):
+            return None
+
+        try:
+            field = self.field
+        except FieldDoesNotExist:
+            return _('This field does not exist any more.')
+        value = json.loads(self.field_value)
+
+        if self.action == 'update':
+            if field.many_to_many:
+                return _('This is a m2m field, so it can\'t be updated.')
+            if field.many_to_one:
+                if value is None and not field.null:
+                    return _('This field has to be set.')
+                try:
+                    self.changeset.wrap(field.related_model).objects.get(pk=value)
+                except ObjectDoesNotExist:
+                    return (_('Referenced %(model_title)s does not exist any more.') %
+                            {'model_title': field.related_model._meta.verbose_name})
+                return None
+            if field.is_relation:
+                raise NotImplementedError
+            try:
+                field.clean(value, obj)
+            except ValidationError as e:
+                return str(e)
+            return None
+
+        if self.action in ('m2m_add', 'm2m_remove'):
+            if not field.many_to_many:
+                return _('This is not a m2m field, so it can\'t be trated as such.')
+            try:
+                self.changeset.wrap(field.related_model).objects.get(pk=value)
+            except ObjectDoesNotExist:
+                return _('Referenced object does not exist any more.')
+            return None
+
+    @property
+    def can_restore(self):
+        if self.discarded_by_id is not None:
+            return False
+
+        if is_created_pk(self.obj_pk):
+            return False
+
+        if self.action == 'delete':
+            return not is_created_pk(self.obj_pk)
+
+        try:
+            obj = get_current_obj(self.model_class, self.obj_pk)
+            field = self.field
+        except (LookupError, ObjectDoesNotExist, FieldDoesNotExist):
+            return True
+
+        if field.many_to_one:
+            return field.null
+
+        if field.name == 'geometry':
+            return False
+
+        try:
+            field.clean(field.get_prep_value(getattr(obj, field.name)), obj)
+        except ValidationError:
+            return False
+
+        return True
+
     def save(self, *args, **kwargs):
         if self.pk is not None:
             raise TypeError('change objects can not be edited (use update to set discarded_by)')

src/c3nav/editor/static/editor/css/editor.css

@@ -168,6 +168,14 @@ form button.invisiblesubmit {
     font-size:14px;
     margin-top: -1px;
 }
+.change-group tr td:last-child .btn {
+    margin-top: -6px;
+    margin-bottom: -2px;
+    margin-right: -5px;
+}
+.change-group tr td:last-child>i {
+    margin-right: -2px;
+}
 
 /* Styles inside leaflet */
 .leaflet-container {

src/c3nav/editor/templates/editor/fragment_change_groups.html

@@ -27,10 +27,20 @@
                         {{ change.value }}
                     </td>
                     <td class="text-muted">
-                        {% if change.author and change.author != changeset.author %}
-                            <i class="glyphicon glyphicon-user" data-toggle="tooltip" data-placement="left" title="{{ change.author.username }}"></i>
+                        {% if change.apply_problem %}
+                            <i class="glyphicon glyphicon-alert text-danger" data-toggle="tooltip" data-placement="left" title="{{ change.apply_problem }}"></i>
+                        {% endif %}
+                        {% if change.author and change.author != changeset.author %}
+                            <i class="glyphicon glyphicon-user text-muted" data-toggle="tooltip" data-placement="left" title="{{ change.author.username }}"></i>
+                        {% endif %}
+                        {% if change.created %}
+                            <i class="glyphicon glyphicon-time text-muted" data-toggle="tooltip" data-placement="left" title="{{ change.created }}"></i>
+                        {% endif %}
+                        {% if change.can_restore %}
+                            <a class="btn btn-xs btn-default" data-toggle="tooltip" data-placement="left" title="{% trans 'Undo this change' %}">
+                                <i class="glyphicon glyphicon-trash"></i>
+                            </a>
                         {% endif %}
-                        <i class="glyphicon glyphicon-time" data-toggle="tooltip" data-placement="left" title="{{ change.created }}"></i>
                     </td>
                 </tr>
             {% endfor %}

src/c3nav/editor/views/changes.py

@@ -120,10 +120,19 @@ def group_changes(changeset, can_edit=False, show_history=False):
         change_data = {
             'pk': change.pk,
             'author': change.author,
-            'created': _('created at %(datetime)s') % {'datetime': date_format(change.created, 'DATETIME_FORMAT')},
             'discarded': change.discarded_by_id is not None,
         }
+        if show_history:
+            change_data.update({
+                'created': _('created at %(datetime)s') % {'datetime': date_format(change.created, 'DATETIME_FORMAT')},
+            })
+        else:
+            change_data.update({
+                'apply_problem': change.check_apply_problem(),
+                'can_restore': change.can_restore,
+            })
         changes.append(change_data)
+
         if change.action == 'create':
             change_data.update({
                 'icon': 'plus',