Merge pull request #889 from aiidateam/fix_for_old_wf_in_sqla_issue_883

Fix for issue #883

aiida/backends/sqlalchemy/models/workflow.py

@@ -246,19 +246,22 @@ def get_or_create(self, **kwargs):  # this is to emulate the django method
 
     def set_value(self, arg):
         from aiida.orm import Node
+        from aiida.backends.sqlalchemy import get_scoped_session
         try:
             if isinstance(arg, Node) or issubclass(arg.__class__, Node):
                 if arg.pk is None:
                     raise ValueError("Cannot add an unstored node as an attribute of a Workflow!")
-                self.aiida_obj = arg.dbnode
+                sess = get_scoped_session()
+                self.aiida_obj = sess.merge(arg.dbnode, load=True)
                 self.value_type = wf_data_value_types.AIIDA
                 self.save()
             else:
                 self.json_value = json.dumps(arg)
                 self.value_type = wf_data_value_types.JSON
                 self.save()
-        except:
-            raise ValueError("Cannot set the parameter {}".format(self.name))
+        except Exception as ex:
+            raise ValueError("Cannot set the parameter {}\n".format(self.name)
+                             + ex.message)
 
     def get_value(self):
         if self.value_type == wf_data_value_types.JSON:

aiida/backends/sqlalchemy/tests/session.py

@@ -20,7 +20,6 @@
 from aiida.common.utils import get_configured_user_email
 
 
-
 class TestSessionSqla(AiidaTestCase):
     """
     The following tests check that the session works as expected in some
@@ -181,3 +180,49 @@ def test_session_update_and_expiration_4(self):
         code.store()
 
         self.drop_connection()
+
+    def test_session_wfdata(self):
+        """
+        This test checks that the
+        aiida.backends.sqlalchemy.models.workflow.DbWorkflowData#set_value
+        method works as expected. There were problems with the DbNode object
+        that was added as a value to a DbWorkflowData object. If there was
+        an older version of the dbnode in the session than the one given to
+        to the DbWorkflowData#set_value then there was a collision in the
+        session and SQLA identity map.
+        """
+        from aiida.orm.node import Node
+        from aiida.workflows.test import WFTestSimpleWithSubWF
+        from aiida.backends.sqlalchemy import get_scoped_session
+        from aiida.orm.utils import load_node
+
+        # Create a node and store it
+        n = Node()
+        n.store()
+
+        # Keep some useful information
+        n_id = n.dbnode.id
+        old_dbnode = n.dbnode
+
+        # Get the session
+        sess = get_scoped_session()
+        # Remove everything from the session
+        sess.expunge_all()
+
+        # Create a workflow and store it
+        wf = WFTestSimpleWithSubWF()
+        wf.store()
+
+        # Load a new version of the node
+        n_reloaded = load_node(n_id)
+
+        # Remove everything from the session
+        sess.expunge_all()
+
+        # Add the dbnode that was firstly added to the session
+        sess.add(old_dbnode)
+
+        # Add as attribute the node that was added after the first cleanup
+        # of the session
+        # At this point the following command should not fail
+        wf.add_attribute('a', n_reloaded)

aiida/orm/implementation/sqlalchemy/workflow.py

@@ -17,7 +17,8 @@
 from aiida.backends.sqlalchemy.models.workflow import DbWorkflow, DbWorkflowStep
 from aiida.backends.utils import get_automatic_user
 from aiida.common import aiidalogger
-from aiida.common.datastructures import wf_states, wf_exit_call
+from aiida.common.datastructures import (wf_states, wf_exit_call,
+                                         wf_default_call)
 from aiida.common.exceptions import (InternalError, ModificationNotAllowed,
                                      NotExistent, ValidationError,
                                      AiidaException)