I have a one2many field on account_voucher, so as to display the deliveries uninvoiced of the selected partner.

For that I overrided the basic_onchange_partner methode of account_voucher, wich displayed tha default accout id of the selected partner, as follow : 

from openerp.osv import fields, orm

class AccountVoucher(orm.Model):

    _inherit = 'account.voucher'
    _name = 'account.voucher'
    _columns = {
        'bls_to_pay': fields.one2many('stock.picking.out','bl_id','BLS to pay'),
    }

    def basic_onchange_partner(self, cr, uid, ids, partner_id, journal_id, ttype, context=None):
        if context==None:
            context={ }
        super(AccountVoucher, self).basic_onchange_partner(cr,uid,ids, partner_id, journal_id, ttype, context)
        DO = self.pool.get('stock.picking.out')
        default = {
            'value': {'bls_to_pay' : [] ,},
        }
        do2pay_ids = DO.search(cr, uid, [('partner_id','=',partner_id),('state','=','done'),('invoice_state','=','2binvoiced')])
        for do2pay in do2pay_ids :
            do_rec= DO.browse(cr, uid, do2pay)
            rs = {
                'num_bl': do_rec.num_bl,
                'date' : do_rec.date,
                'origin': do_rec.origin,
            }
            default['value']['bls_to_pay'].append(rs) 
        return default

When selecting the partner, an error occurs ( Client side ) saying : Uncaught Error: Champ state inconnu dans le domaine [["state","in",["cancel","done"]]]

and giving the following location : /web/static/src/js/view_form.js:1675

Why this error rises ?