From 9c613b92b10ba485f0aa5041aee95dbcd9162fb2 2012-08-03 16:09:41
From: Lance Edgar <lance@edbob.org>
Date: 2012-08-03 16:09:41
Subject: [PATCH] add db.cache module

---

diff --git a/rattail/db/cache.py b/rattail/db/cache.py
new file mode 100644
index 0000000000000000000000000000000000000000..640a99b154ed0b30c781d421885cb909cb30466d
--- /dev/null
+++ b/rattail/db/cache.py
@@ -0,0 +1,114 @@
+#!/usr/bin/env python
+# -*- coding: utf-8  -*-
+################################################################################
+#
+#  Rattail -- Retail Software Framework
+#  Copyright © 2010-2012 Lance Edgar
+#
+#  This file is part of Rattail.
+#
+#  Rattail is free software: you can redistribute it and/or modify it under the
+#  terms of the GNU Affero General Public License as published by the Free
+#  Software Foundation, either version 3 of the License, or (at your option)
+#  any later version.
+#
+#  Rattail is distributed in the hope that it will be useful, but WITHOUT ANY
+#  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+#  FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for
+#  more details.
+#
+#  You should have received a copy of the GNU Affero General Public License
+#  along with Rattail.  If not, see <http://www.gnu.org/licenses/>.
+#
+################################################################################
+
+"""
+``rattail.db.cache`` -- Cache Helpers
+"""
+
+import edbob
+from edbob.util import requires_impl
+
+import rattail
+
+
+class DataCacher(edbob.Object):
+
+    def __init__(self, session=None, **kwargs):
+        super(DataCacher, self).__init__(session=session, **kwargs)
+
+    @property
+    @requires_impl(is_property=True)
+    def class_(self):
+        pass
+    
+    @property
+    def name(self):
+        return self.class_.__name__
+
+    def get_cache(self, progress):
+        self.instances = {}
+
+        query = self.session.query(self.class_)
+        count = query.count()
+        if not count:
+            return self.instances
+        
+        prog = None
+        if progress:
+            prog = progress("Reading Rattail %s records into cache" % self.name, count)
+
+        cancel = False
+        for i, instance in enumerate(query, 1):
+            self.cache_instance(instance)
+            if prog and not prog.update(i):
+                cancel = True
+                break
+
+        if prog:
+            prog.destroy()
+
+        if cancel:
+            session.close()
+            return None
+        return self.instances
+
+
+class DepartmentCacher(DataCacher):
+
+    class_ = rattail.Department
+
+    def cache_instance(self, dept):
+        self.instances[dept.number] = dept
+
+
+class SubdepartmentCacher(DataCacher):
+
+    class_ = rattail.Subdepartment
+
+    def cache_instance(self, subdept):
+        self.instances[subdept.number] = subdept
+
+
+class BrandCacher(DataCacher):
+
+    class_ = rattail.Brand
+
+    def cache_instance(self, brand):
+        self.instances[brand.name] = brand
+
+
+class VendorCacher(DataCacher):
+
+    class_ = rattail.Vendor
+
+    def cache_instance(self, vend):
+        self.instances[vend.id] = vend
+
+
+class ProductCacher(DataCacher):
+
+    class_ = rattail.Product
+
+    def cache_instance(self, prod):
+        self.instances[prod.upc] = prod