Feature/95 provider super (#96)

SQLAlchemyProvider: use super().__init__()

Issue #95

skosprovider_sqlalchemy/models.py

@@ -329,7 +329,7 @@ class Collection(Thing):
     members = relationship(
         'Thing',
         secondary=collection_concept,
-        backref=backref('member_of', collection_class=set),
+        backref=backref('member_of', collection_class=set, cascade_backrefs=False),
         primaryjoin='Thing.id==collection_concept.c.collection_id',
         secondaryjoin='Thing.id==collection_concept.c.concept_id',
         collection_class=set

skosprovider_sqlalchemy/providers.py

@@ -57,40 +57,44 @@ def __init__(self, metadata, session, **kwargs):
         :param :class:`sqlachemy.orm.session.Session` session: The database
         session. This can also be a callable that returns a Session.
         '''
-        if 'subject' not in metadata:
-            metadata['subject'] = []
-        self.metadata = metadata
-        if 'uri_generator' in kwargs:
-            self.uri_generator = kwargs.get('uri_generator')
-        else:
-            self.uri_generator = DefaultUrnGenerator(self.metadata.get('id'))
+        super().__init__(
+            metadata,
+            allowed_instance_scopes=['single', 'threaded_thread'],
+            concept_scheme=None,
+            **kwargs
+        )
         try:
             self.session = session()
         except TypeError:
             self.session = session
+
         try:
-            self.conceptscheme_id = int(metadata.get(
-                'conceptscheme_id', metadata.get('id')
-            ))
-        except ValueError:
+            self.conceptscheme_id = int(
+                metadata.get('conceptscheme_id', metadata.get('id'))
+            )
+        except (ValueError, TypeError):
             raise ValueError(
                 'Please provide a valid integer for the conceptscheme_id.'
             )
+
         if 'expand_strategy' in kwargs:
             if kwargs['expand_strategy'] in ['recurse', 'visit']:
                 self.expand_strategy = kwargs['expand_strategy']
             else:
                 raise ValueError(
                     'Unknown expand strategy.'
                 )
-        self.allowed_instance_scopes = ['single', 'threaded_thread']
 
     @property
     def concept_scheme(self):
         if self._conceptscheme is None:
             self._conceptscheme = self._get_concept_scheme()
         return self._conceptscheme
 
+    @concept_scheme.setter
+    def concept_scheme(self, _):
+        """Ignore the super class setting a concept_scheme."""
+
     def _get_concept_scheme(self):
         '''
         Find a :class:`skosprovider.skos.ConceptScheme` for this provider.