global: avoid double versioned models registration

* Checks for already registered models before building versioning
  models. (closes #96)

invenio_db/ext.py

@@ -35,6 +35,7 @@
 
 from .cli import db as db_cmd
 from .shared import db
+from .utils import versioning_models_registered
 
 
 class InvenioDB(object):
@@ -95,7 +96,8 @@ def init_db(self, app, entry_point_group='invenio_db.models', **kwargs):
         if app.config['DB_VERSIONING']:
             manager = self.versioning_manager
             if manager.pending_classes:
-                manager.builder.configure_versioned_classes()
+                if not versioning_models_registered(manager, database.Model):
+                    manager.builder.configure_versioned_classes()
             elif 'transaction' not in database.metadata.tables:
                 manager.declarative_base = database.Model
                 manager.create_transaction_model()

invenio_db/utils.py

@@ -89,3 +89,19 @@ def drop_alembic_version_table():
         alembic_version = _db.Table('alembic_version', _db.metadata,
                                     autoload_with=_db.engine)
         alembic_version.drop(bind=_db.engine)
+
+
+def versioning_model_classname(manager, model):
+    """Get the name of the versioned model class."""
+    if manager.options.get('use_module_name', True):
+        return '%s%sVersion' % (
+            model.__module__.title().replace('.', ''), model.__name__)
+    else:
+        return '%sVersion' % (model.__name__,)
+
+
+def versioning_models_registered(manager, base):
+    """Return True if all versioning models have been registered."""
+    declared_models = base._decl_class_registry.keys()
+    return all(versioning_model_classname(manager, c) in declared_models
+               for c in manager.pending_classes)

tests/test_utils.py

@@ -26,10 +26,14 @@
 
 import pytest
 import sqlalchemy as sa
+from mock import patch
+from sqlalchemy_continuum import remove_versioning
 from sqlalchemy_utils.types.encrypted import EncryptedType
+from test_db import _mock_entry_points
 
 from invenio_db import InvenioDB
-from invenio_db.utils import rebuild_encrypted_properties
+from invenio_db.utils import rebuild_encrypted_properties, \
+    versioning_model_classname, versioning_models_registered
 
 
 def test_rebuild_encrypted_properties(db, app):
@@ -73,3 +77,22 @@ class Demo(db.Model):
 
     with app.app_context():
         db.drop_all()
+
+
+def test_versioning_model_classname(db, app):
+    """Test the versioning model utilities."""
+    class FooClass(db.Model):
+        __versioned__ = {}
+        pk = db.Column(db.Integer, primary_key=True)
+
+    app.config['DB_VERSIONING'] = True
+    idb = InvenioDB(app)
+    manager = idb.versioning_manager
+    manager.options['use_module_name'] = True
+    assert versioning_model_classname(manager, FooClass) == \
+        'Test_UtilsFooClassVersion'
+    manager.options['use_module_name'] = False
+    assert versioning_model_classname(
+        manager, FooClass) == 'FooClassVersion'
+    assert versioning_models_registered(manager, db.Model)
+    remove_versioning(manager=manager)