如何更改类的构造函数以接收已创建的类和构造函数的对象的通用列表？ （C＃）

Question

I have the following class:

public class OrderArticlesAdapter : RecyclerView.Adapter
{
    public List<OrderArticleViewModel> listOfOrderArticles;
    .....
    .....
    //constructor
    public OrderArticlesAdapter(List<OrderArticleViewModel> orderArticles, ....., .....)
    {
        listOfOrderArticles = orderArticles;
        ......
    }
}

I want the class to be able to work not only with list of OrderArticleViewModel but also with list of type Invoices and any other type. OrderArticleViewModel class looks like that:

public class OrderArticleViewModel
{
    public string ArticleId { get; set; }

    public string LotId { get; set; }

    public string ArticleName { get; set; }

    public string PriceDiscount { get; set; }

    public string ArticlePrice { get; set; }

    public string ArticleQuantity { get; set; }

    public string ArticleTotalPrice { get; set; }

    public string Barcode { get; set; }

    public string ExpireDate { get; set; }

    public string LotName { get; set; }

    public string ArticlePriceAfterDiscount
    {
        get
        {
            decimal priceDiscount;
            if (!Decimal.TryParse(PriceDiscount, out priceDiscount))
            {
                priceDiscount = 0;
            }
            decimal articlePrice = Convert.ToDecimal(ArticlePrice);
            decimal discountAmount = Math.Round(articlePrice * (priceDiscount / 100), 4);
            decimal articlePriceAfterDiscount = articlePrice - discountAmount;
            return articlePriceAfterDiscount.ToString();
        }
    }
}

Invoices class looks like that:

public class Invoices
{
    public string ArtId { get; set; }
    public string Name { get; set; }
    public string Quantity { get; set; }
    public string Price { get; set; }
    public string Sum { get; set; }
    public string Discount { get; set; }
    public string PriceWodiscount { get; set; }
    public string Id { get; set; }
}

ArticleId , ArticleName , ArticleQuantity , PriceDiscount , ArticlePrice , Discount , ArticlePriceAfterDiscount from class OrderArticleViewModel correspond to properties ArtId , Name , Quantity , Discount , Price , Sum from class Invoices . How do I make OrderArticlesAdapter constructor to be able to recieve generic list of OrderArticleViewModel or Invoices or any other type without breaking the functionality of the code where I already have used instance of OrderArticlesAdapter ?

Answer 1

Create another constructor in which you convert the invoice list to an ArticleViewModel list:

public class OrderArticlesAdapter : RecyclerView.Adapter
{
    public List<OrderArticleViewModel> listOfOrderArticles;

    public OrderArticlesAdapter(List<OrderArticleViewModel> orderArticles, ....., .....)
    {
        listOfOrderArticles = orderArticles;
    }

    public OrderArticlesAdapter(List<Invoice> invoices)
    {
        listOfOrderArticles = invoices.Select(MapToArticleVM).ToList();
    }

    private OrderArticleViewModel MapToArticleVM(Invoice invoice)
    {
        return new OrderArticleViewModel
        {
            ArticleId = invoice.ArtId,
            // ...
        };
    }
}

Do note the resulting list will miss some properties, because Invoice doesn't contain Barcode , for example.

Answer 2

One option would be to write an extension method to convert an invoice to view model

public static class InvoicesExtensions
{
    public static OrderArticleViewModel ToOrderArticleViewModel(this Invoices i)
    {
        return new OrderArticleViewModel { ArticleId = i.ArtId, ... };
    }
}

... and then you can call the constructor like

var invoices = new List<Invoices>();

var adapter = new OrderArticlesAdapter(invoices.Select(i => i.ToOrderArticleViewModel()).ToList());

I would also recommend

• renaming Invoices to Invoice as it seems to represent an actual invoice not multiple invoices
• use IEnumerable<OrderArticleViewModel> instead of List<OrderArticleViewModel> for the constructor parameter as this makes the constructor more versatile