Weight discrepency : Rate Calculator

What is the purpose of this article?

This article aims to develop an API that would offer clients a means to calculate the shipping charges between their pickup postal code (from the warehouse's location) and the drop-off postal code (the customer's location) based on the types of couriers.

Based on the shipping charges, clients can decide the courier they want to ship the order.

Rate Calculator Figma

WIP | June 2023

Examples: Courier_Rate_Calculator_.xlsx

DB Models

1. Table name - fees_types

What are the steps to achieving this task?

Note - New Endpoint will be made to achieve this task in the below project

1. The user fills in the details on a workspace and clicks on the calculate button. Then POST /ratecalculatorAPI gets hit with the below request body from frontend

   { "journeyType": "forward", "pickupPincode": "110001", "dropPincode": "835210", "pickupPincodeState" : "RN", "dropPincodeState" : "DL", "orderWeight": 500.5, "length": 100.5, "breadth": 50.5, "height": 10.5. "paymentMethod": "Prepaid", }

2. From the endpoint, Call a function calculateRatesByPincodes. This function will be developed in service layer.

3. In this function, perform the following steps:-

   1. Create a model class (baseRatesModel) for the table base_rates_model which contains the data about what will be the charges based on zones and order weight for every account (workspace).

   2. Based on pickup pincode and drop pincode, calculate the zone (use the same logic as used in inventory allocation)

   3. Fetch the details from memchache or by hibernate query in baseRatesModel class and store the result in baseRatesModelList.

   4. Call a function prepareSequenceListByOrderWeight. This function will be developed in helper layer. Inside this function perform the below task.

      1. Set a minimumWeight int value = 0

      2. Define two empty lists - chargeableWeightSequenceList<Double> and chargeableAmountList<Integer>

      3. Iterate over the baseRatesModelList

         1. Divide the (max weight - minimum weight) by per weight and store the result in a new variable int slabs.

         2. Add values in the above-defined lists limited to the value of slabs.

            1. chargeableWeightSequenceList contains the weight sequence which will be taken into consideration for calculating the charges. Here the value of per_weight will be added.

            2. chargeableAmountList contains the chargeable amount. The chargeable amount should be only for the calculated zone. Here the value of rate of the zone will be added.

         3. Update minimum weight variable by the value of max weight

            Logic with Example :- (500 - 0) / 500 = 1 ===> [500], [22] (2000 - 500) / 500 = 3 ===> [500, 500, 500, 500], [22, 20, 20, 20] (5000 - 2000) / 1000 = 3 ===> [500, 500, 500, 500, 1000, 1000, 1000], [22, 20, 20, 20, 22, 22, 22]

         4. Return both the prepared list in a map.

   5. Once the two lists are prepared, calculateCourierwiseRatesByWeight function. This function will be prepared in helper layer. Perform the below tasks in this function :-

      1. Get the orderWeight from the request body.

      2. Define a variable int totalChargeableWeight = 0 and intTotalAmount = 0

      3. Iterate over the chargeableWeightSequenceList

         1. If orderWeight > totalChargeableWeight , then break

         2. Update totalChargeableWeight = totalChargeableWeight + chargeableWeightSequenceList.index value of iteration

         3. Update totalAmount = totalAmount + chargeableAmountList.index value of iteration

         4. and for each value keep adding the amount from the chargeableAmountList till the time the orderWeight is not greater than the total of chargeableWeightSequenceList iteration.

      4. Once the amount is calculated, get feesTypes details and accountAddionalFees details from the Memcache or by hibernate query from fees_types and account_additional_fees respectively.

      5. Prepare a Map<String, Dto> for accountAddionalFees where the key will be fee_types_id and value will be accountAddionalFees model row.

      6. Get the journeyType from the request body

      7. Iterate over the feesTypes details

         1. if feesTypesDetails.resource = journeyType

            1. Get the accountAddionalFees model row by fee_types_id from the prepared Map.

            2. If Calculation_type = flat then directly add the fees in the totalAmount.

            3. If calculation_type = percent the calculate the percentage and add the value in the total amount.

      8. Return the courierwise response from the function

4. Add the request DTO along with the prepared courierwise response

5. Return the response to the frontend.