Fix load & dump commands

pyplanner/database.py

@@ -47,6 +47,8 @@ class Database:
         instances_dict = {}
 
         for k, v in self.models.items():
+            if v.__subclasses__():
+                continue
             instances = [i for i in session.query(v).all()]
             instances_dict[k] = instances
             yaml.register_class(v)
@@ -62,3 +64,8 @@ class Database:
         for k, v_list in instances_dict.items():
             model = self.models[k]
             instances = [model(**v) for v in v_list]
+
+            for i in instances:
+                session.merge(i)
+
+        session.commit()