--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/soc/models/survey_record_group.py	Sun Jun 28 13:18:56 2009 +0200
@@ -0,0 +1,70 @@
+#!/usr/bin/python2.5
+#
+# Copyright 2009 the Melange authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""SurveyRecordGroup represents a cluster (mentor/student) of SurveyRecords
+for an evaluation period.
+"""
+
+__authors__ = [
+  '"Daniel Diniz" <ajaksu@gmail.com>',
+  '"James Levy" <jamesalexanderlevy@gmail.com>',
+]
+
+
+from google.appengine.ext import db
+
+from soc.models.survey_record import SurveyRecord
+import soc.models.user
+
+
+class SurveyRecordGroup(db.Expando):
+  """Because Mentors and Students take different surveys,
+  we cannot simply link survey records by a common project and survey.
+
+  Instead, we establish a SurveyRecordGroup.
+
+  A SurveyRecordGroup links a group of survey records with a common
+  project, and links back to its records. 
+
+  This entity also includes the current project_status at its creation.
+  This property is used as a filter in lookups and acts as a safeguard
+  against unpredictable behavior. 
+  """
+
+  #: Mentor SurveyRecord for this evaluation.
+  mentor_record = db.ReferenceProperty(SurveyRecord, required=False,
+                              collection_name='mentor_record_groups')
+
+  #: Student SurveyRecord for this evaluation.
+  student_record = db.ReferenceProperty(SurveyRecord, required=False,
+                              collection_name='student_record_groups')
+
+  #: Project for this evaluation.
+  project = db.ReferenceProperty(soc.models.student_project.StudentProject,
+                                collection_name="survey_record_groups",
+                                required=True)
+
+  # Status of project at start of evaluation.
+  initial_status = db.StringProperty(required=True)
+
+  #: Status of project at end of evaluation.
+  final_status = db.StringProperty(required=False)
+
+  #: Property containing the date that this SurveyRecordGroup was created.
+  created = db.DateTimeProperty(auto_now_add=True)
+
+  #: Property containing the last date that this SurveyRecordGroup was modified.
+  modified = db.DateTimeProperty(auto_now=True)