odoo Onchange装饰器

<!-- content of form view -->
<field name="amount"/>
<field name="unit_price"/>
<field name="price" readonly="1"/>

# onchange handler
@api.onchange(‘amount‘, ‘unit_price‘)
def _onchange_price(self):
    # set auto-changing field
    self.price = self.amount * self.unit_price
    # Can optionally return a warning and domains
    return {
        ‘warning‘: {
            ‘title‘: "Something bad happened",
            ‘message‘: "It was very bad indeed",
        }
    }