account_bank_statement_report/registro_caja.py

from openerp import api, models

class report_registro_caja(models.AbstractModel):
    _name = 'report.account_bank_statement_report.report_registro_caja'

    @api.multi
    def render_html(self, data=None):
        report_obj = self.env['report']
        report = report_obj._get_report_from_name('account_bank_statement_report.report_registro_caja')
        docargs = {
            'doc_ids': self._ids,
            'doc_model': report.model,
            'docs': self.env[report.model].browse(self._ids),
            'get_sub_total_pos': self._get_sub_total_pos,
            'get_sub_total_neg': self._get_sub_total_neg,
            'get_total': self._get_total,
        }
        return report_obj.render('account_bank_statement_report.report_registro_caja', docargs)

    def _get_sub_total_pos(self,statement_line_ids):
        subtotal = 0.0
        for line in statement_line_ids:
            if line.amount > 0:
                subtotal += line.amount
        return subtotal

    def _get_sub_total_neg(self,statement_line_ids):
        subtotal = 0.0
        for line in statement_line_ids:
            if line.amount < 0:
                subtotal += line.amount
        return subtotal

    def _get_total(self, statement_line_ids):
        total = 0.0
        for line in statement_line_ids:
            total += line.amount
        return total