继承wizard并传递数据

[hui]

odoo8中sale.order通过按钮创建invoice，代码是通过wizard传递数据的。

现在想要多传递一个值，sale.order中记录了invoice_ids，（但invoice中没有记录sale.order的信息）现在要把sale.order的一个char值给传递给invoice。

尝试：
继承wizard，在传值的方法中添加一个值传递，但是报错如下：

Traceback (most recent call last):
  File "/home/hui/.local/lib/python2.7/site-packages/werkzeug/serving.py", line 193, in run_wsgi
    execute(self.server.app)
  File "/home/hui/.local/lib/python2.7/site-packages/werkzeug/serving.py", line 181, in execute
    application_iter = app(environ, start_response)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/service/server.py", line 294, in app
    return self.app(e, s)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/service/wsgi_server.py", line 216, in application
    return application_unproxied(environ, start_response)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/service/wsgi_server.py", line 202, in application_unproxied
    result = handler(environ, start_response)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/http.py", line 1299, in __call__
    return self.dispatch(environ, start_response)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/http.py", line 1273, in __call__
    return self.app(environ, start_wrapped)
  File "/home/hui/.local/lib/python2.7/site-packages/werkzeug/wsgi.py", line 599, in __call__
    return self.app(environ, start_response)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/http.py", line 1444, in dispatch
    ir_http = request.registry['ir.http']
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/http.py", line 355, in registry
    return openerp.modules.registry.RegistryManager.get(self.db) if self.db else None
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/modules/registry.py", line 339, in get
    update_module)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/modules/registry.py", line 370, in new
    openerp.modules.load_modules(registry._db, force_demo, status, update_module)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/modules/loading.py", line 351, in load_modules
    force, status, report, loaded_modules, update_module)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/modules/loading.py", line 255, in load_marked_modules
    loaded, processed = load_module_graph(cr, graph, progressdict, report=report, skip_modules=loaded_modules, perform_checks=perform_checks)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/modules/loading.py", line 152, in load_module_graph
    models = registry.load(cr, package)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/modules/registry.py", line 163, in load
    model = cls._build_model(self, cr)
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/models.py", line 595, in _build_model
    original_module = pool[name]._original_module if name in parents else cls._module
  File "/home/hui/odoo-dev/odoo8/odoo/openerp/modules/registry.py", line 102, in __getitem__
    return self.models[model_name]
KeyError: 'sale.order.line.make.invoice'