如何在发票odoo v11中添加新的税额

Question

我正在使用odoo 11，并且我创建了一个自定义模块以在发票中添加新的税额。我注意到此代码在odoo 9中可以使用，但在odoo 11中未返回任何内容，也没有显示错误。任何想法和帮助请解决此问题

account_invoice.py

from odoo import models, fields, osv

class fiscal_stamp(models.Model):
_inherit = "res.company"
description = fields.Many2one('account.account' , string='Libellé Taxe')
montant = fields.Float(string='Montant')

class account_invoice(osv.osv):
_name = "account.invoice"
_inherit = "account.invoice"

def create(self, cr, uid, values, context=None):
    invoice_id = super(account_invoicing, self).create(cr, uid, values, context)

    res_company = self.pool.get('res.company')

    stamp_account = res_company.browse(cr, uid, values.get('company_id')).description.id
    tax_value = res_company.browse(cr, uid, values.get('company_id')).montant

    if stamp_account:
        account_invoice_tax = self.pool.get('account.invoice.tax')

        tax_line_values = {'base': 0,
                           'amount': tax_value,
                           'name': 'Timbre',
                           'account_id': stamp_account,
                           'invoice_id': invoice_id
                           }

        account_invoice_tax.create(cr, uid, tax_line_values)

    return invoice_id