我的switch语句怎么了？

Question

我只是通过switch语句向该代码行添加了排序功能，但switch语句似乎没有任何作用...我错过了什么吗？ 我是一个新手，所以我可能会出错，并且我的错误可能存在于代码的其他地方，所以请耐心等待。 同样，对于使这一行代码更有效率的方法提出了一些建议也将受到欢迎。 谢谢。

        public ProductGetAllActiveResponse GetAllActiveProducts(ProductGetActiveRequest request)
    {
        IEnumerable<SalesOrderHeader> salesOrderMatches = DataModel.SalesOrderHeaders
                                                                   .Where(s => s.CustomerID == request.CustomerId &&
                                                                               s.OrderDate > request.Startdate &&
                                                                               s.OrderDate < request.EndDate);


        ProductGetAllActiveResponse response = new ProductGetAllActiveResponse();

        List<ProductActiveResponse> products = new List<ProductActiveResponse>();     

        foreach (var item in salesOrderMatches)
        {
            foreach (var item2 in item.SalesOrderDetails)
            {
                var product = DataModel.Products.FirstOrDefault(n => n.ProductID == item2.ProductID);
                ProductActiveResponse newResponse = new ProductActiveResponse();
                newResponse.Color = product.Color;
                newResponse.DiscontinuedDate = product.DiscontinuedDate;
                newResponse.ListPrice = product.ListPrice;
                newResponse.Name = product.Name;
                newResponse.OrderDate = item.OrderDate;
                newResponse.ProductId = product.ProductID;
                newResponse.ProductLine = product.ProductLine;
                newResponse.ProductModelId = product.ProductModelID;
                newResponse.ProductNumber = product.ProductNumber;
                newResponse.Style = product.Style;
                products.Add(newResponse);
            }
        }

        response.IndexSize = products.Count();

        IEnumerable<ProductActiveResponse> test;

        switch(request.SortMember)
        {
            case "ProductId":
                if (request.SortDirection == 1)
                   test = products.OrderBy(m => m.ProductId);
                else
                   test = products.OrderByDescending(m => m.ProductId);
                break;
            case "ListPrice":
                if (request.SortDirection == 1)
                    test = products.OrderBy(m => m.ListPrice);
                else
                    test = products.OrderByDescending(m => m.ListPrice);
                break;
            case "Color":
                if (request.SortDirection == 1)
                   test =  products.OrderBy(m => m.Color);
                else
                    test = products.OrderByDescending(m => m.Color);
                break;
            case "OrderDate":
                if (request.SortDirection == 1)
                    test = products.OrderBy(m => m.OrderDate);
                else
                    test = products.OrderByDescending(m => m.OrderDate);
                break;
            default:
                   test =  products.OrderBy(m => m.OrderDate);
                break;
        }


        var trimmedProducts = test.Skip((request.Page - 1) * request.ProductsPerPage).Take(request.ProductsPerPage);

        foreach (var item in trimmedProducts)
        {
            response.ActiveProducts.Add(item);
        }

        if (response.ActiveProducts.Count() == 0)
            response.Success = false;
        else
            response.Success = true;

        return response;
    }

Answer 1

OrderBy和OrderByDescending不会修改现有集合。 它们返回一个新排序的IEnumerable，由于未分配任何内容，因此将其丢弃。

您可以执行以下操作：

IEnumerable<ProductActiveResponse> sortedProducts;

...

sortedProducts = product.OrderBy(m => m.OrderDate);

...

var trimmedProducts = sortedProducts.Skip((request.Page - 1) * request.ProductsPerPage).Take(request.ProductsPerPage);

Answer 2

问题不在于switch语句，而是您对OrderBy的使用，而不是将结果分配给变量。

OrderBy和OrderByDescending返回IEnumerable<T>集合。

更改

products.OrderBy(m => m.OrderDate);

至

products = products.OrderBy(m => m.OrderDate);

它将起作用。