override the default_get like:

    @api.model
    def default_get(self, fields):
        res = super(AccountMoveLineReconcile, self).default_get(fields)
        data = self.trans_rec_get()
        if 'trans_nbr' in fields:
            res.update({'trans_nbr': data['trans_nbr']})
        if 'credit' in fields:
            res.update({'credit': data['credit']})
        if 'debit' in fields:
            res.update({'debit': data['debit']})
        if 'writeoff' in fields:
            res.update({'writeoff': data['writeoff']})
        return res

YES ! RESOLU

impec cela m'as aidé. Pour un wizard

@api.model
def default_get(self, fields):    
    res = super(WizardBusinessCreator, self).default_get(fields)    
    entreprise = self.env.user.company_id    
    myNextId = getNextAnalyticName(self, entreprise.id)    
    if 'description' in fields:        
    res.update({'description': myNextId})    
    return res