Rework versioning support to allow it to be one or off.

Turns out versioning isn't quite ready for prime time, so let's have a
fallback plan shall we?

tailbone/auth.py

@@ -31,14 +31,15 @@ from pyramid.interfaces import IAuthorizationPolicy
 from pyramid.security import Everyone, Authenticated
 
 from .db import Session
-from rattail.db.model import User
-from rattail.db.auth import has_permission
 
 
 @implementer(IAuthorizationPolicy)
 class TailboneAuthorizationPolicy(object):
 
     def permits(self, context, principals, permission):
+        from rattail.db.model import User
+        from rattail.db.auth import has_permission
+
         for userid in principals:
             if userid not in (Everyone, Authenticated):
                 user = Session.query(User).get(userid)

tailbone/db.py

@@ -32,7 +32,7 @@ import sqlalchemy_continuum as continuum
 from sqlalchemy.orm import sessionmaker, scoped_session
 
 from rattail.db import SessionBase
-from rattail.db import model
+from rattail.db.continuum import versioning_manager
 
 
 Session = scoped_session(sessionmaker(class_=SessionBase))
@@ -53,8 +53,7 @@ class TailboneSessionDataManager(datamanager.SessionDataManager):
         if self.tx is not None:  # there may have been no work to do
 
             # Force creation of Continuum versions for current session.
-            mgr = continuum.get_versioning_manager(model.Product) # any ol' model will do
-            uow = mgr.unit_of_work(self.session)
+            uow = versioning_manager.unit_of_work(self.session)
             uow.make_versions(self.session)
 
             self.tx.commit()

tailbone/templates/brands/crud.mako

@@ -8,7 +8,7 @@
   % elif form.updating:
       <li>${h.link_to("View this Brand", url('brand.read', uuid=form.fieldset.model.uuid))}</li>
   % endif
-  % if not form.creating and request.has_perm('brand.versions.view'):
+  % if version_count is not Undefined and request.has_perm('brand.versions.view'):
       <li>${h.link_to("View Change History ({0})".format(version_count), url('brand.versions', uuid=form.fieldset.model.uuid))}</li>
   % endif
 </%def>

tailbone/templates/departments/crud.mako

@@ -8,7 +8,7 @@
   % elif form.updating:
       <li>${h.link_to("View this Department", url('department.read', uuid=form.fieldset.model.uuid))}</li>
   % endif
-  % if not form.creating and request.has_perm('department.versions.view'):
+  % if version_count is not Undefined and request.has_perm('department.versions.view'):
       <li>${h.link_to("View Change History ({0})".format(version_count), url('department.versions', uuid=form.fieldset.model.uuid))}</li>
   % endif
 </%def>

tailbone/templates/products/crud.mako

@@ -8,7 +8,7 @@
   % elif form.updating:
       <li>${h.link_to("View this Product", url('product.read', uuid=form.fieldset.model.uuid))}</li>
   % endif
-  % if not form.creating and request.has_perm('product.versions.view'):
+  % if version_count is not Undefined and request.has_perm('product.versions.view'):
       <li>${h.link_to("View Change History ({0})".format(version_count), url('product.versions', uuid=form.fieldset.model.uuid))}</li>
   % endif
 </%def>

tailbone/templates/subdepartments/crud.mako

@@ -8,7 +8,7 @@
   % elif form.updating:
       <li>${h.link_to("View this Subdepartment", url('subdepartment.read', uuid=form.fieldset.model.uuid))}</li>
   % endif
-  % if not form.creating and request.has_perm('subdepartment.versions.view'):
+  % if version_count is not Undefined and request.has_perm('subdepartment.versions.view'):
       <li>${h.link_to("View Change History ({0})".format(version_count), url('subdepartment.versions', uuid=form.fieldset.model.uuid))}</li>
   % endif
 </%def>

tailbone/templates/vendors/crud.mako

@@ -8,7 +8,7 @@
   % elif form.updating:
       <li>${h.link_to("View this Vendor", url('vendor.read', uuid=form.fieldset.model.uuid))}</li>
   % endif
-  % if not form.creating and request.has_perm('vendor.versions.view'):
+  % if version_count is not Undefined and request.has_perm('vendor.versions.view'):
       <li>${h.link_to("View Change History ({0})".format(version_count), url('vendor.versions', uuid=form.fieldset.model.uuid))}</li>
   % endif
 </%def>

tailbone/views/continuum.py

@@ -30,7 +30,7 @@ import sqlalchemy as sa
 import sqlalchemy_continuum as continuum
 
 from rattail.db import model
-from rattail.db.model.continuum import model_transaction_query
+from rattail.db.continuum import model_transaction_query
 
 import formalchemy
 from pyramid.httpexceptions import HTTPNotFound

tailbone/views/crud.py

@@ -37,7 +37,7 @@ from sqlalchemy_continuum import transaction_class, version_class
 from sqlalchemy_continuum.utils import is_versioned
 
 from rattail.db import model
-from rattail.db.model.continuum import count_versions, model_transaction_query
+from rattail.db.continuum import count_versions, model_transaction_query
 
 from pyramid.httpexceptions import HTTPFound, HTTPNotFound