get_amount.py

from collections import defaultdict
@api.depends('document_ids', 'document_ids.residual',
                'document_ids.payment', 'document_ids.total')
def _get_amount(self):
    field_sum = ['payment', 'total', 'aawp_id']
    field_spans = ['span01', 'span02', 'span03', 'span04', 'span05']
    for record in self:
        res = defaultdict(float)
        direction = record.aaw_id.direction == 'past'
        spans = [record.aaw_id.period_length * x * (direction and 1 or -1)
                    for x in range(5)]
        vals = record.document_ids.read_group(
            [('aawp_id', '=', record.id)], field_sum, ['aawp_id'])

        vals = vals[0] if vals else {}
        
        res['payment'] += vals[0].get('payment', 0)
        res['total'] += vals[0].get('total', 0)

        vals = record.document_ids.read_group(
            [('aawp_id', '=', record.id),
             ('due_days', '<=' if direction else '>', 0)],
            ['residual', 'aawp_id'], ['aawp_id'])
        
        if vals:
            res['not_due'] += vals[0].get('residual', 0)
        else:
            record._get_amount_span(
                field_spans, res, doc, spans, direction)
        record.update(res)