Cancellation of an order with reason for cancellation (Node.js)

In this use case, the user cancels the order. Sometimes, the seller asks for a reason for cancellation before cancelling the order that the user has to provide. The seller’s cancellation policy is also communicated to the user on or before the cancellation of the order. The cancellation policy includes terms like cancellation charges, last time of cancellation, refund policy etc

Code snippets

Client calls the BAP server to trigger cancel:

    router.post("/local_retail/cancel_order", cancelOrder);

    async function cancelOrder({ body }, res) {
        try {
            // Get the cancellation reasons metadata from the BPP Meta API
            //  .. Validate the client request before below function
            await generateCancelRequest(body)
        } catch (error) {
            res.status(500).send(httpResponse("NACK", error));
        }
    };

BAP server generates the protocol request body

    async function generateCancelRequest(clientRequestBody) {
/*
Example Request JSON :
{
    "context": {
        "domain": "nic2004:52110",
        "country": "IND",
        "city": "std:080",
        "action": "cancel",
        "core_version": "0.9.2",
        "bap_id": "https://mock_bap.com/",
        "bap_uri": "https://mock_bap.com/beckn/",
        "bpp_id": "https://mock_bpp.com/",
        "bpp_uri": "https://mock_bpp.com/beckn/",
        "transaction_id": "1209849124",
        "message_id": "1234124234237",
        "timestamp": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "order_id": "order_1",
        "cancellation_reason_id": "reason_3"
    }
}
*/
        //The below code generates the above example JSON.
        const transactionId = _.get(body, "transactionId");
        // Returns the Context including MessageId
        const context = createContext(transactionId);
        // Create
        const cancelRequestBody = {
            context,
            message: {
                // Construct from the request
            }
        };
        //call protocol Cancel Request
        const response = await callCancelRequest(cancelRequestBody);
        res
        .status(200)
        .send({ ...response.data, messageId: context["message_id"] });
    }

BAP server calls protocol cancel to the network

    async function callCancelRequest(cancelRequestBody) {
        // It lookups the registry for BG OR BPP
        let uri = lookup();
        // Construct Header
        const headers = constructAuthHeader(); // Auth Header with digital Signature
        return axios({ url: `${uri}$/local_retail/cancel`, method: "POST", data: cancelRequestBody, headers});
    }

BAP receives protocol on_cancel

/*
Example Response JSON:
{
    "context": {
        "domain": "nic2004:52110",
        "country": "IND",
        "city": "std:080",
        "action": "on_cancel",
        "core_version": "0.9.2",
        "bap_id": "https://mock_bap.com/",
        "bap_uri": "https://mock_bap.com/beckn/",
        "bpp_id": "https://mock_bpp.com/",
        "bpp_uri": "https://mock_bpp.com/beckn/",
        "transaction_id": "1209849124",
        "message_id": "12341242345",
        "timestamp": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "order": {
            "id":"order_1",
            "state":"Cancelled",
            "items":[
                {
                    "id": "item_1",
                    "quantity": {
                        "count": 2
                    }
                },
                {
                    "id": "item_2",
                    "quantity": {
                        "count": 1
                    }
                }
            ],
            "billing": {
                "name": "John Doe",
                "address": {
                    "door": "21A",
                    "name": "ABC Apartments",
                    "locality": "HSR Layout",
                    "city": "Bengaluru",
                    "state": "Karnataka",
                    "country": "India",
                    "area_code": "560102"
                },
                "email": "[email protected]",
                "phone": "+919876543210"
            },
            "fulfillment": {
                "type": "home-delivery",
                "tracking": false,
                "start": {
                    "location": {
                        "id": "koramangala-4th-block-location",
                        "descriptor": {
                            "name": "Pooja Stores"
                        },
                        "gps": "12.9349377,77.6055586"
                    },
                    "time": {
                        "range": {
                            "start": "2021-06-15T07:09:30.000Z",
                            "end": "2021-06-15T07:10:30.000Z"
                        }
                    },
                    "instructions": {
                        "name": "pick up instructions",
                        "short_desc": "Provide the order id"
                    },
                    "contact": {
                        "phone": "+919999999999",
                        "email": "[email protected]"
                    }
                },
                "end": {
                    "location": {
                        "gps": "12.914028, 77.638698",
                        "address": {
                            "door": "21A",
                            "name": "ABC Apartments",
                            "locality": "HSR Layout",
                            "city": "Bengaluru",
                            "state": "Karnataka",
                            "country": "India",
                            "area_code": "560102"
                        }
                    },
                    "time": {
                        "range": {
                            "start": "2021-06-15T07:11:36.212Z",
                            "end": "2021-06-15T07:12:36.212Z"
                        }
                    },
                    "instructions": {
                        "name": "drop off instructions",
                        "short_desc": "Leave at door step"
                    },
                    "contact": {
                        "phone": "+919876543210",
                        "email": "[email protected]"
                    }
                }
            },
            "quote": {
                "price": {
                    "currency": "INR",
                    "value": "370"
                },
                "breakup": [
                    {
                        "title": "Red Apples",
                        "price": {
                            "currency": "INR",
                            "value": "180"
                        }
                    },
                    {
                        "title": "Green Apples Organic",
                        "price": {
                            "currency": "INR",
                            "value": "170"
                        }
                    },
                    {
                        "title": "Delivery Charges",
                        "price": {
                            "currency": "INR",
                            "value": "20"
                        }
                    }
                ]
            },
            "payment": {
                "uri": "https://api.bpp.com/pay?amt=$640&mode=upi&vpa=bpp@upi",
                "tl_method": "http/get",
                "params": {
                    "amount": "640",
                    "mode": "upi",
                    "vpa": "bpp@upi"
                },
                "type": "ON-FULFILLMENT",
                "status": "NOT-PAID"
            }
        }
    }
}
*/
    // Auth middleware authenticates the digital signature of the incoming request
    router.post("/local_retail/on_cancel", auth, onCancel);
    async function onCancel({ body }, res) {
        // Save the response to Database
        await saveToDb(body);
    };

Client polls BAP to get the on_cancel results

    // Endpoint for the client to poll the search data based on the message id
    async function getMessageById(req) {
        try {
            const messageId = _.get(req, "messageId");
            // Get the data using message Id
            const response = await getData(messageId);
            res.status(200).send(httpResponse('ACK', "", response));
        } catch(error) {
            res.status(500).send(httpResponse("NACK", error));
        }
    };