Abstract workflow models.

shared/utils/models/workflow.py

@@ -0,0 +1,123 @@
+from django.conf import settings
+from django.db import models
+from django.utils import timezone
+from django.utils.translation import gettext_lazy as _
+
+#
+# Workflow Helpers
+
+"""
+States:
+- inactive (either active=False or publication date not reached)
+- public (active or archived)
+- active (public, not archived)
+- archived (public, not active)
+"""
+
+
+class WorkflowQuerySet(models.QuerySet):
+    @classmethod
+    def exclude_inactive_filter(cls):
+        """Usage: qs.exclude(**self.exclude_inactive_filter())"""
+        return {
+            "is_published": True,
+            "publication_datetime__lte": timezone.now().date(),
+        }
+
+    @classmethod
+    def active_filter(cls):
+        return {
+            "is_published": True,
+            "publication_datetime__lte": timezone.now().date(),
+            "archiving_datetime__gte": timezone.now().date(),
+        }
+
+    @classmethod
+    def archived_filter(cls):
+        return {
+            "is_published": True,
+            "publication_datetime__lte": timezone.now().date(),
+            "archiving_datetime__lte": timezone.now().date(),
+        }
+
+    def public(self):
+        # Active or archived
+        return self.exclude(**self.exclude_inactive_filter())
+
+    def active(self):
+        return self.filter(**self.active_filter())
+
+    def archived(self):
+        return self.filter(**self.archived_filter())
+
+
+class ManyToManyWorkflowQuerySet(WorkflowQuerySet):
+    def _build_related_filters(self, filter_template):
+        """
+        Transforms all filter rules to match any related models which 
+        itself is workflow managed.
+        """
+        filter = {}
+        for field in self.model._meta.get_fields():
+            if field.many_to_one and isinstance(field.related_model._meta.default_manager, WorkflowManager):
+                field.name
+                for path, value in filter_template.items():
+                    filter[f'{field.name}__{path}'] = value
+        return filter
+
+    def public(self):
+        # Active or archived
+        return self.exclude(**self._build_related_filters(self.exclude_inactive_filter()))
+
+    def active(self):
+        return self.filter(**self._build_related_filters(self.active_filter()))
+
+    def archived(self):
+        return self.filter(**self._build_related_filters(self.archived_filter()))
+
+
+class WorkflowManager(models.Manager.from_queryset(WorkflowQuerySet)):
+    pass        
+
+
+class ManyToManyWorkflowManager(models.Manager.from_queryset(ManyToManyWorkflowQuerySet)):
+    pass
+
+
+class WorkflowMixin(models.Model):
+    creation_datetime = models.DateTimeField(auto_now_add=True)
+    modification_datetime = models.DateTimeField(auto_now=True)
+    creation_user = models.ForeignKey(settings.AUTH_USER_MODEL, null=True,
+        editable=False,
+        on_delete=models.SET_NULL, related_name='+')
+    modification_user = models.ForeignKey(settings.AUTH_USER_MODEL, null=True,
+        editable=False,
+        on_delete=models.SET_NULL, related_name='+')
+
+    is_published = models.BooleanField(_("Publicly visible"), default=False)
+    publication_datetime = models.DateTimeField(_("Publication Date"), default=timezone.now)
+    archiving_datetime = models.DateTimeField(_("Archiving Date"), default=timezone.datetime.max)
+
+    objects = WorkflowManager()
+
+    class Meta:
+        abstract = True
+        ordering = ['-publication_datetime']  # Most recent first
+
+    @property
+    def worflow_status(self):
+        now = timezone.now()
+        if not self.is_active or self.publication_datetime < now:
+            return 'inactive'
+        elif self.publication_datetime >= now and self.archiving_datetime < now:
+            return 'active'
+        else:
+            return 'archived'
+
+
+def display_is_active(obj):
+    return obj.is_publised and obj.publication_datetime <= timezone.now()
+
+
+display_is_active.boolean = True
+display_is_active.short_description = _("Aktiv")