import json

conditions = {'id': params_kw.get('id', '')}
data = {}
for key in ['template_id', 'customer_id', 'code', 'status', 'source', 'remark']:
    val = params_kw.get(key, None) if hasattr(params_kw, 'get') else None
    if val is not None:
        data[key] = val

result = await update_voucher_instance(conditions, data)
return json.dumps(result)