Code layout change.

[wolnelektury.git] / src / newtagging / managers.py

diff --git a/src/newtagging/managers.py b/src/newtagging/managers.py
new file mode 100644 (file)
index 0000000..0bfec54
--- /dev/null
+++ b/src/newtagging/managers.py
@@ -0,0 +1,81 @@
+# -*- coding: utf-8 -*-
+"""
+Custom managers for Django models registered with the tagging
+application.
+"""
+from django.contrib.contenttypes.models import ContentType
+from django.db import models
+
+
+class ModelTagManager(models.Manager):
+    """
+    A manager for retrieving tags for a particular model.
+    """
+    def __init__(self, tag_model):
+        super(ModelTagManager, self).__init__()
+        self.tag_model = tag_model
+
+    def get_queryset(self):
+        content_type = ContentType.objects.get_for_model(self.model)
+        return self.tag_model.objects.filter(
+            items__content_type__pk=content_type.pk).distinct()
+
+    def related(self, tags, *args, **kwargs):
+        return self.tag_model.objects.related_for_model(tags, self.model, *args, **kwargs)
+
+    def usage(self, *args, **kwargs):
+        return self.tag_model.objects.usage_for_model(self.model, *args, **kwargs)
+
+
+class ModelTaggedItemManager(models.Manager):
+    """
+    A manager for retrieving model instances based on their tags.
+    """
+    def __init__(self, tag_model):
+        super(ModelTaggedItemManager, self).__init__()
+        self.intermediary_table_model = tag_model.objects.intermediary_table_model
+
+    def related_to(self, obj, queryset=None):
+        if queryset is None:
+            return self.intermediary_table_model.objects.get_related(
+                obj, self.model)
+        else:
+            return self.intermediary_table_model.objects.get_related(
+                obj, queryset)
+
+    def with_all(self, tags, queryset=None):
+        if queryset is None:
+            return self.intermediary_table_model.objects.get_by_model(self.model, tags)
+        else:
+            return self.intermediary_table_model.objects.get_by_model(queryset, tags)
+
+    def with_any(self, tags, queryset=None):
+        if queryset is None:
+            return self.intermediary_table_model.objects.get_union_by_model(self.model, tags)
+        else:
+            return self.intermediary_table_model.objects.get_union_by_model(queryset, tags)
+
+
+class TagDescriptor(object):
+    """
+    A descriptor which provides access to a ``ModelTagManager`` for
+    model classes and simple retrieval, updating and deletion of tags
+    for model instances.
+    """
+    def __init__(self, tag_model):
+        self.tag_model = tag_model
+
+    def __get__(self, instance, owner):
+        if not instance:
+            tag_manager = ModelTagManager(self.tag_model)
+            tag_manager.model = owner
+            return tag_manager
+        else:
+            return self.tag_model.objects.get_for_object(instance)
+
+    def __set__(self, instance, value):
+        self.tag_model.objects.update_tags(instance, value)
+
+    def __del__(self, instance):
+        self.tag_model.objects.update_tags(instance, [])
+