Hi, I try to include "('type', '=', 'invoice')" into the penultimate line  ->  

          domain.extend([('recurring_next_date', '<=', date_ref)])

in order to get  ->

          domain.extend([('recurring_next_date', '<=', date_ref),('type', '=', 'invoice')])

Is there any way to achive it? 

The original function is the following:

class ContractContract(models.Model):

    _name = 'contract.contract'

@api.model

    def _get_contracts_to_invoice_domain(self, date_ref=None):

        domain = []

        if not date_ref:

            date_ref = fields.Date.context_today(self)

        domain.extend([('recurring_next_date', '<=', date_ref)])

        return domain