New process schema definition and implementation

capsul/database/__init__.py

@@ -412,14 +412,13 @@ def update_executable(self, engine_id, execution_id, executable):
                 node, parameters = stack.pop(0)
                 for field in node.user_fields():
                     value = parameters.get(field.name, undefined)
+                    value = parameters.no_proxy(value)
+                    if value is None:
+                        value = undefined
                     if value is not undefined:
-                        value = parameters.no_proxy(value)
-                        if value is None:
-                            value = undefined
-                        # print('!update_executable!', node.full_name, field.name, '<-', repr(value))
+                        if isinstance(value, list) and field.is_list():
+                            value = list((undefined if i is None else i) for i in value)
                         setattr(node, field.name, value)
-                    # else:
-                    #     print('!update_executable! ignore', node.full_name, field.name, repr(value))
                 if isinstance(node, Pipeline):
                     stack.extend(
                         (n, parameters["nodes"][n.name])