Interface IDiscountExtenderCalculateProductDiscount

Namespace

Dynamicweb.Ecommerce.Orders.Discounts

Assembly

Dynamicweb.Ecommerce.dll

Implement this interface on a DiscountExtenderBase implementation to take over the calculation of a discount for a product

public interface IDiscountExtenderCalculateProductDiscount

Examples

using System;
using Dynamicweb.Core;
using Dynamicweb.Ecommerce.International;
using Dynamicweb.Ecommerce.Prices;
using Dynamicweb.Ecommerce.Products;
using Dynamicweb.Extensibility.AddIns;
using Dynamicweb.Extensibility.Editors;

namespace Dynamicweb.Ecommerce.Orders.Discounts;

public sealed class SetAmountFromProductAsFinalPriceExtender : DiscountExtenderBase, IDiscountExtenderCalculateProductDiscount
{
    [
        AddInParameter("Calculate discount based on amount field"), 
        AddInDescription("Will set the final discounted price of a product to the value specified on the product custom field."), 
        AddInParameterEditor(typeof(YesNoParameterEditor), "")
    ]
    public bool CalculateDiscountToReachSpecifiedDiscountPrice { get; set; }

    PriceInfo IDiscountExtenderCalculateProductDiscount.GetDiscount(Product product, Currency currency, Country country)
    {
        ArgumentNullException.ThrowIfNull(product, nameof(product));
        ArgumentNullException.ThrowIfNull(currency, nameof(currency));
        ArgumentNullException.ThrowIfNull(country, nameof(country));

        //Locating the amount set on the product in the custom field. We want to use this value as the final price after discount for this product.
        double amountFromProductField = Converter.ToDouble(product.ProductFieldValues.GetProductFieldValue(Discount.AmountProductFieldName).Value);
        if (amountFromProductField > 0)
        {
            //Load the price information located on the product in a custom field into a price calculated to handle vat etc.
            PriceCalculated priceFromCustomField = PriceCalculated.Create(currency, country, new PriceRaw(amountFromProductField, currency));
            priceFromCustomField.Calculate();

            if (CalculateDiscountToReachSpecifiedDiscountPrice)
            {
                //Find the calculated price for this product
                var priceContext = new PriceContext(currency, country);
                PriceInfo priceFromProduct = product.GetPrice(priceContext);

                //calculate what the discount must be in order to achieve a product price with discount that reflects what is in the custom field on the product
                PriceInfo theDiscount = priceFromProduct.Substract(priceFromCustomField);

                return theDiscount;
            }
            else
                return priceFromCustomField;
        }
        else
        {
            var calculated = PriceCalculated.Create(currency, country, new PriceRaw(0d, currency));
            calculated.Calculate();

            return calculated;
        }
    }

    public override bool DiscountValidForProduct(Product product)
    {
        ArgumentNullException.ThrowIfNull(product, nameof(product));

        //This discount needs a field name specified in order to work
        if (string.IsNullOrEmpty(Discount.AmountProductFieldName)) 
            return false;

        //This discount only works if the field has a positive value
        double fieldValue = Converter.ToDouble(product.ProductFieldValues.GetProductFieldValue(Discount.AmountProductFieldName).Value);
        if (fieldValue > 0) 
            return true;

        return false;
    }

    public override bool DiscountValidForOrder(Order order)
    {
        //this discount type only applies for products
        return false;
    }
}

Remarks

If this interface is implemented it takes over discount calculation for a product.

Methods

GetDiscount(Product, Currency, Country)

Return the discount amount as a priceinfo that should be given to the passed product

PriceInfo GetDiscount(Product product, Currency currency, Country country)

Parameters

product Product

The product to calculate the discount for

currency Currency

country Country

Returns

PriceInfo

The amount that is wanted to be given in discount