Receiving a search intent based on product price range and sending a list of items whose price falls in that range (Node.js)

In this use case, the user enters the price range before searching for a product. This can be combined with any other use case that results in a list of items

Code snippets

BPP receives protocol search

/*
Example Request JSON:
{
    "context": {
        "domain": "local_retail",
        "country": "IND",
        "city": "std:080",
        "action": "search",
        "core_version": "0.9.2",
        "bap_id": "https://mock_bap.com/",
        "bap_uri": "https://mock_bap.com/beckn/",
        "transaction_id": "1239890342",
        "message_id": "123793824",
        "timestamp": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "intent" : {
            "item": {
                "price" : {
                    "currency": "INR",
                    "minimum_value": "50",
                    "maximum_value": "300"
                }
            },
            "fulfillment": {
                "end": {
                    "location": {
                        "gps": "12.4535445,77.9283792"
                    }
                }
            }
        }
    }
}``
*/
    // Auth middleware authenticates the digital signature of the incoming request
    router.post('/local_retail/search', auth, search);

    function search({ headers, body }, res) {
        try {
            const message = _.get(body, "message");
            const context = _.get(body, "context");
            if (!context) {
                return res.status(400).send(httpResponse("NACK", "Missing Context"));
            }
            if (!message) {
                return res.status(400).send(httpResponse("NACK", "Missing Message"));
            }
            // ... Returns the ack immediately and continue the processing after validation
            res.status(200).send(httpResponse("ACK"));
            processSearch(headers, body)
        } catch (error) {
            res.status(500).send(httpResponse("NACK", error));
        }
    };

BPP processes the search

   function processSearch(requestHeaders, searchRequestBody) {
        // Execute business logic here
        let searchResponse = {

        }
        generateResponse(requestHeaders, searchResponse)
    }

BPP generates response

    async function generateResponse(requestHeaders, rawResponse){
/*
Example Request JSON :
{
    "context": {
        "domain": "nic2004:52110",
        "country": "IND",
        "city": "std:080",
        "action": "on_search",
        "core_version": "0.9.1",
        "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": "12341242343",
        "timestamp": "2021-03-23T10:00:40.065Z"
    },
    "message": {
        "catalog": {
            "bpp/descriptor": {
                "name": "Mock BPP"
            },
            "bpp/providers": [
                {
                    "id": "pooja-stores",
                    "descriptor" : {
                        "name": "Pooja Stores"
                    },
                    "locations": [
                        {
                            "id": "koramangala-4th-block-location",
                            "gps": "12.9349377,77.6055586"
                        }
                    ],
                    "categories": [
                        {
                            "id": "fresh_fruits",
                            "descriptor": {
                                "name": "Fresh Fruits"
                            }
                        },
                        {
                            "id": "beverages",
                            "descriptor": {
                                "name": "Beverages"
                            }
                        },
                    ],
                    "items": [
                        {
                            "id": "item_2",
                            "descriptor" : {
                                "name" : "Green Apples Organic",
                                "images" : [
                                    "https://mock_bpp.com/images/item_2.jpg"
                                ]
                            },
                            "category_id": "fresh_fruits",
                            "location_id": "koramangala-4th-block-location",
                            "price" : {
                                "currency": "INR",
                                "value": "170"
                            },
                            "matched": true
                        },
                        {
                            "id": "item_1",
                            "descriptor" : {
                                "name" : "Red Apples",
                                "images" : [
                                    "https://mock_bpp.com/images/item_1.jpg"
                                ]
                            },
                            "category_id": "fresh_fruits",
                            "location_id": "koramangala-4th-block-location",
                            "price" : {
                                "currency": "INR",
                                "value": "90"
                            },
                            "related": true
                        },
                        {
                            "id": "item_7",
                            "descriptor" : {
                                "name" : "Green Apple Juice",
                                "images" : [
                                    "https://mock_bpp.com/images/item_7.jpg"
                                ]
                            },
                            "category_id": "beverages",
                            "location_id": "koramangala-4th-block-location",
                            "price" : {
                                "currency": "INR",
                                "value": "70"
                            },
                            "matched": true
                        },
                    ]
                },
                {
                    "id": "food-mall",
                    "descriptor": {
                        "name": "Food Mall"
                    },
                    "locations": [
                        {
                            "id": "food-mall-location",
                            "gps": "12.9349377,77.6055586"
                        }
                    ],
                    "categories": [
                        {
                            "id": "fresh-food": {
                                "name": "Fresh food"
                            }
                        }
                    ],
                    "items": [
                        {
                            "id": "item_1_1",
                            "descriptor" : {
                                "name" : "Green Apple Salad",
                                "images" : [
                                    "https://mock_bpp.com/images/item_1_1.jpg"
                                ]
                            },
                            "category_id": "fresh-food",
                            "location_id": "food-mall-location",
                            "price" : {
                                "currency": "INR",
                                "value": "200"
                            },
                            "matched": true
                        }
                    ]
                }
            ],
            "bpp/fulfillments": [
                {
                    "type": "home-delivery"
                }
            ]
        }
    }
}
*/
        //The below code generates the above example JSON.
        let onSearchResponseBody = { }
        //call protocol on_search
        await callOnSearch(requestHeaders, onSearchResponseBody);
    }

BPP calls protocol on_search

    async function callOnSearch(requestHeaders, onSearchResponseBody) {
        // Take the subscriber Id from the header and calls the registry to get the url. If already cached it need not to call again
        const uri = await lookup(requestHeaders);
        // Construct Header
        const headers = constructAuthHeader(); // Auth Header with digital Signature
        return axios({ url: `${uri}/local_retail/on_search`, method: "POST", headers, data: onRatingResponseBody });
    }