I want to inherit the value of amount_total from accounts module to my custom module. amount_total is a field in accounts module, so how can I retrieve it's value in my custom module. I already have set depends on account in my __openerp__ file. But still in eclipse it says as undefined variable:amount_total

custom.py ,

class account_invoice(models.Model):

    _inherit = "account.invoice"  

    print amount_total