AttributeError: 'NoneType' object has no attribute '_columns'

问题

I am writing a module in OpenERP that would inherit from the Accounts module. Below is my simplified code

from osv import fields, osv
import decimal_precision as dp

class account_molly(osv.osv):

    def __computeOB(self, cr, uid, ids, context=None):
        res = []
        return 0

    def __computeCB(self, cr, uid, ids, context=None):
        res = []
        return 0

    _name = "account.molly"
    _description = "This is Molly Special Account View"
    _inherit = "account.account"
    _columns = {
        'opening_balance': fields.function(__computeOB, digits_compute=dp.get_precision('Account'), method=True, string='Opening Balance'),
        'end_balance': fields.function(__computeCB, digits_compute=dp.get_precision('Account'), method=True, string='End Balance'),
    }   

account_molly()

# vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4:

When I try to install the module, I get

AttributeError: 'NoneType' object has no attribute '_columns'

Please what could be the problem

回答1:

Please check the dependency of the module you have created. In the openerp.py file, in the dependency list if 'account' is not added, please add it. If this didnt solve your problem please provide the error log

回答2:

does this solve the problem?

class account_molly(osv):
    ... 

you seem to mix module and class and class attribute

来源：https://stackoverflow.com/questions/10565288/attributeerror-nonetype-object-has-no-attribute-columns