ARIA-158 Restore support for relationship ordering

aria/modeling/relationship.py

@@ -14,7 +14,6 @@
 # limitations under the License.
 
 # pylint: disable=invalid-name, redefined-outer-name
-
 from sqlalchemy.orm import relationship, backref
 from sqlalchemy.orm.collections import attribute_mapped_collection
 from sqlalchemy import (
@@ -161,7 +160,8 @@ def one_to_many(model_class,
                 child_table,
                 child_fk=None,
                 dict_key=None,
-                back_populates=None):
+                back_populates=None,
+                rel_kwargs=None):
     """
     Declare a one-to-many relationship property. The property value would be a list or dict of
     instances of the child table's model.
@@ -186,6 +186,8 @@ def one_to_many(model_class,
                            false to disable
     :type back_populates: basestring|bool
     """
+    rel_kwargs = rel_kwargs or {}
+    rel_kwargs.setdefault('cascade', 'all')
     if back_populates is None:
         back_populates = model_class.__tablename__
     return _relationship(
@@ -194,7 +196,7 @@ def one_to_many(model_class,
         back_populates=back_populates,
         other_fk=child_fk,
         dict_key=dict_key,
-        relationship_kwargs=dict(cascade='all'))
+        relationship_kwargs=rel_kwargs)
 
 
 def many_to_one(model_class,

aria/modeling/service_instance.py

@@ -25,6 +25,7 @@
 from sqlalchemy import DateTime
 from sqlalchemy.ext.associationproxy import association_proxy
 from sqlalchemy.ext.declarative import declared_attr
+from sqlalchemy.ext.orderinglist import ordering_list
 
 from .mixins import InstanceModelMixin
 from ..orchestrator import execution_plugin
@@ -485,12 +486,22 @@ def capabilities(cls):
     @declared_attr
     def outbound_relationships(cls):
         return relationship.one_to_many(
-            cls, 'relationship', child_fk='source_node_fk', back_populates='source_node')
+            cls, 'relationship', child_fk='source_node_fk', back_populates='source_node',
+            rel_kwargs=dict(
+                order_by='Relationship.source_position',
+                collection_class=ordering_list('source_position', count_from=0)
+            )
+        )
 
     @declared_attr
     def inbound_relationships(cls):
         return relationship.one_to_many(
-            cls, 'relationship', child_fk='target_node_fk', back_populates='target_node')
+            cls, 'relationship', child_fk='target_node_fk', back_populates='target_node',
+            rel_kwargs=dict(
+                order_by='Relationship.target_position',
+                collection_class=ordering_list('target_position', count_from=0)
+            )
+        )
 
     # endregion
 
@@ -1166,9 +1177,9 @@ class RelationshipBase(InstanceModelMixin):
     :vartype properties: {basestring: :class:`Parameter`}
     :ivar interfaces: Bundles of operations
     :vartype interfaces: {basestring: :class:`Interfaces`}
-    :ivar source_position: ??
+    :ivar source_position: The position of the relationship in the outbound relationships.
     :vartype source_position: int
-    :ivar target_position: ??
+    :ivar target_position: The position of the relationship in the inbound relationships.
     :vartype target_position: int
     :ivar source_node: Source node
     :vartype source_node: :class:`Node`
@@ -1185,7 +1196,9 @@ class RelationshipBase(InstanceModelMixin):
                           'target_node_fk',
                           'target_capability_fk',
                           'requirement_template_fk',
-                          'relationship_template_fk']
+                          'relationship_template_fk',
+                          'target_position',
+                          'source_position']
 
     # region foreign keys
 
@@ -1289,8 +1302,8 @@ def properties(cls):
 
     # endregion
 
-    source_position = Column(Integer) # ???
-    target_position = Column(Integer) # ???
+    source_position = Column(Integer)
+    target_position = Column(Integer)
 
     def configure_operations(self):
         for interface in self.interfaces.itervalues():

tests/modeling/test_mixins.py

@@ -155,15 +155,18 @@ def flip_and_assert(node, direction):
         """
         assert direction in ('inbound', 'outbound')
 
-        relationships = getattr(node, direction + '_relationships')
+        def get_relationships():
+            return getattr(node, direction + '_relationships')
+
+        relationships = get_relationships()
         assert len(relationships) == 2
 
         reversed_relationship = list(reversed(relationships))
         assert relationships != reversed_relationship
 
         relationships[:] = reversed_relationship
         context.model.node.update(node)
-        assert relationships == reversed_relationship
+        assert get_relationships() == reversed_relationship
 
     flip_and_assert(source_node, 'outbound')
     flip_and_assert(target_node, 'inbound')