remove history-meta for templates, replace with hand-made history table

history-meta's dynamic magic is insufficient for templates, where we
need to be able to refer to the specific history table to take
advantage of sqlalchemy's relationship management (2/3rds of an ORM).
So replace it with a custom made version table.

Had to change the version decorator slightly for this

app/dao/dao_utils.py

@@ -1,6 +1,7 @@
 import itertools
-from functools import wraps
-from app.history_meta import versioned_objects, create_history
+from functools import wraps, partial
+
+from app.history_meta import create_history
 
 
 def transactional(func):
@@ -19,14 +20,16 @@ def transactional(func):
     return commit_or_rollback
 
 
-def version_class(model_class):
+def version_class(model_class, history_cls=None):
+    create_hist = partial(create_history, history_cls=history_cls)
+
     def versioned(func):
         @wraps(func)
         def record_version(*args, **kwargs):
             from app import db
             func(*args, **kwargs)
-            history_objects = [create_history(obj) for obj in
-                               versioned_objects(itertools.chain(db.session.new, db.session.dirty))
+            history_objects = [create_hist(obj) for obj in
+                               itertools.chain(db.session.new, db.session.dirty)
                                if isinstance(obj, model_class)]
             for h_obj in history_objects:
                 db.session.add(h_obj)

app/dao/services_dao.py

@@ -16,6 +16,7 @@ from app.models import (
     VerifyCode,
     ApiKey,
     Template,
+    TemplateHistory,
     Job,
     NotificationHistory,
     Notification,
@@ -122,7 +123,7 @@ def delete_service_and_all_associated_db_objects(service):
     _delete_commit(Notification.query.filter_by(service=service))
     _delete_commit(Job.query.filter_by(service=service))
     _delete_commit(Template.query.filter_by(service=service))
-    _delete_commit(Template.get_history_model().query.filter_by(service_id=service.id))
+    _delete_commit(TemplateHistory.query.filter_by(service_id=service.id))
 
     verify_codes = VerifyCode.query.join(User).filter(User.id.in_([x.id for x in service.users]))
     list(map(db.session.delete, verify_codes))

app/dao/templates_dao.py

@@ -1,8 +1,9 @@
 import uuid
-from app import db
-from app.models import (Template, Service)
+
 from sqlalchemy import (asc, desc)
 
+from app import db
+from app.models import (Template, TemplateHistory)
 from app.dao.dao_utils import (
     transactional,
     version_class
@@ -10,7 +11,7 @@ from app.dao.dao_utils import (
 
 
 @transactional
-@version_class(Template)
+@version_class(Template, TemplateHistory)
 def dao_create_template(template):
     template.id = uuid.uuid4()  # must be set now so version history model can use same id
     template.archived = False
@@ -18,14 +19,14 @@ def dao_create_template(template):
 
 
 @transactional
-@version_class(Template)
+@version_class(Template, TemplateHistory)
 def dao_update_template(template):
     db.session.add(template)
 
 
 def dao_get_template_by_id_and_service_id(template_id, service_id, version=None):
     if version is not None:
-        return Template.get_history_model().query.filter_by(
+        return TemplateHistory.query.filter_by(
             id=template_id,
             service_id=service_id,
             version=version).one()
@@ -34,7 +35,7 @@ def dao_get_template_by_id_and_service_id(template_id, service_id, version=None)
 
 def dao_get_template_by_id(template_id, version=None):
     if version is not None:
-        return Template.get_history_model().query.filter_by(
+        return TemplateHistory.query.filter_by(
             id=template_id,
             version=version).one()
     return Template.query.filter_by(id=template_id).one()
@@ -50,6 +51,8 @@ def dao_get_all_templates_for_service(service_id):
 
 
 def dao_get_template_versions(service_id, template_id):
-    history_model = Template.get_history_model()
-    return history_model.query.filter_by(service_id=service_id, id=template_id).order_by(
-        desc(history_model.version)).all()
+    return TemplateHistory.query.filter_by(
+        service_id=service_id, id=template_id
+    ).order_by(
+        desc(TemplateHistory.version)
+    ).all()