Add published state to session model

Author: summerhenson

sasdata/fair_database/data/models.py

@@ -142,11 +142,13 @@ class Session(Data):
     """Database model for a project save state."""
 
     # dataset
-    # dataset = models.ForeignKey(DataSet, on_delete=models.CASCADE)
+    # dataset = models.ManyToManyField(DataSet)
 
     # operation tree
     # operations = models.ForeignKey(OperationTree, on_delete=models.CASCADE)
 
+    published_state = models.ForeignKey("PublishedState", blank=True, null=True, on_delete=SET_NULL)
+
 class PublishedState():
     """Database model for a project published state."""