import json

data = {}
for key in ['instance_id', 'customer_id', 'order_id', 'face_value', 'deducted_amount', 'used_at', 'used_by', 'product_type', 'product_name']:
    val = params_kw.get(key, None) if hasattr(params_kw, 'get') else None
    if val is not None:
        data[key] = val

result = await create_voucher_usage_log(data)
return json.dumps(result)