[galaxy-dev] how to access galaxy model in the tool wrapper

Hi all, Do you know any way to access galaxy model (like 'HistoryDatasetAssociation') in the tool wrapper python file for a newly added tool, without overriding 'exec_after_process(app, inp_data, out_data, param_dict, tool, stdout, stderr)'? Thank you very much. Best Regards, -Bingxin