account_bank_voucher_import/model/account_bank_voucher_import.py

# -*- coding: utf-8 -*-
from openerp import models, fields, api,  _
from openerp.exceptions import Warning

class AccountBankStatement(models.Model):
    _inherit = 'account.bank.statement'

    def button_cancel(self, cr, uid, ids, context=None):
        context['cancel_from_statement'] = True
        return super(AccountBankStatement, self).button_cancel(cr, uid, ids, context=context)

class AccountBankStatementLine(models.Model):
    _inherit = 'account.bank.statement.line'

    voucher_id = fields.Many2one('account.voucher', 'Voucher', readonly=True)

    def cancel(self, cr, uid, ids, context=None):
        # if we are canceling the statement then we dont raise the warning
        if context.get('cancel_from_statement', False):
            none_voucher_ids = self.search(cr, uid, [('id', 'in', ids), ('voucher_id', '=', False)])
            return super(AccountBankStatementLine, self).cancel(cr, uid, none_voucher_ids, context)

        for line in self.browse(cr, uid, ids, context):
            if line.voucher_id:
                raise Warning(_("You can not cancel a line that has been imported from a Voucher, you should cancel the voucher first"))
            return super(AccountBankStatementLine, self).cancel(cr, uid, ids, context)

        account_move_obj = self.pool.get('account.move')
        move_ids = []
        for line in self.browse(cr, uid, ids, context=context):
            if line.journal_entry_id:
                move_ids.append(line.journal_entry_id.id)
                for aml in line.journal_entry_id.line_id:
                    if aml.reconcile_id:
                        move_lines = [l.id for l in aml.reconcile_id.line_id]
                        move_lines.remove(aml.id)
                        self.pool.get('account.move.reconcile').unlink(cr, uid, [aml.reconcile_id.id], context=context)
                        if len(move_lines) >= 2:
                            self.pool.get('account.move.line').reconcile_partial(cr, uid, move_lines, 'auto', context=context)
        if move_ids:
            account_move_obj.button_cancel(cr, uid, move_ids, context=context)
            account_move_obj.unlink(cr, uid, move_ids, context)

    def unlink(self, cr, uid, ids, context=None):
        line_voucher_ids = self.search(cr, uid, [('id', 'in', ids), ('voucher_id', '!=', False)])
        # First remove journal_entry_id id in order to avoid constraint
        self.write(cr, uid, line_voucher_ids, {'journal_entry_id': False})
        return super(AccountBankStatementLine, self).unlink(cr, uid, ids, context=context)

class AccountVoucher(models.Model):
    _inherit = 'account.voucher'

    bank_statement_line_ids = fields.One2many('account.bank.statement.line', 'voucher_id', string="Statement Lines")

    @api.multi
    def cancel_voucher(self):
        # run with sudo because some users may not have access to statement line
        if self.sudo().bank_statement_line_ids.statement_id.state == 'confirm':
            raise Warning(_("You can not cancel a payment that is linked to a cash register."))
        else:
            super(AccountVoucher, self).cancel_voucher()
            return self.sudo().bank_statement_line_ids.unlink()