I have create a new module which has more number of fields I called this in python as a column

from openerp.osv import fields, osv

class autobuy_fields(osv.osv):

_name = "autobuy.fields"

_description = "autobuy fields"

_columns = {

'name': fields.char('Source'),

'created':fields.datetime('Created'),

'vin':fields.char('Vin'),

'year':fields.selection([('2012'), ('2013'), ('2014')]),

'make':fields.selection([('Jeep'), ('SUV'), ('TUV')]),

'model':fields.selection([('Model1'), ('Model2'), ('Mopdel3')]),

'color':fields.char('Color'),

'mileage':fields.float('Purchased Mileage'),

'boffer':fields.float('AutoBuy Offer'),

'coffer':fields.float('Customer Offer'),

'soffer':fields.float('Second AutoBuy Offer'),

'amount':fields.float('Purchase Amount'),

'price':fields.float('Asking Price'),

'aoffer':fields.float('AutoTrader Offer'),

'sroffer':fields.float('SR Buyer Offer'),

'samount':fields.float('Sold Amount'),

'fname':fields.char('First Name'),

'lname':fields.char('Last Name'),

'cname':fields.char('Co-Owner Name'),

'address':fields.char('Address'),

'city':fields.char('City'),

'state':fields.char('State'),

'zip':fields.integer('Zip'),

'cphone':fields.integer('Cell Phone'),

'hphone':fields.integer('Home Phone'),

'email':fields.integer('Email'),

'pdate':fields.date('Purchase Date'),

'udate':fields.date('Pickup Date'),

'stock':fields.char('Stock No'),

}

It shows error as "too many columns to unpack" If I give only 8 fields it does not shows error If I give more than 8 values it shows the error.

How can I solve this or it only take 8 fields?