dsLinq.Count() 引发了“System.NullReferenceException”类型的异常

最新推荐文章于 2024-01-10 19:08:52 发布

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最新推荐文章于 2024-01-10 19:08:52 发布

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CC 4.0 BY-SA版权

文章标签： c# 数据库

原文链接：http://www.cnblogs.com/Jeremy2001/p/9124290.html

本文介绍了一种使用LINQ进行数据排序的方法，并通过具体的代码示例展示了如何从XML数据集中提取信息并按指定字段排序。同时，文章还讨论了在处理过程中可能遇到的NullReferenceException异常及其解决方法。

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DataTable dt = PurchaseArriveInfoBus.GetPurchaseArriveInfo(companyCD, txtArriveNo, txtTitle, txtProvider);
        XElement dsXML = ConvertDataTableToXML(dt);
        //linq排序
        var dsLinq =
            (order == "ascending") ?
            (from x in dsXML.Descendants("Data")
             orderby x.Element(orderBy).Value ascending
             select new DataSourceModel()
             {
                 ID = x.Element("ID").Value,
                 ArriveNo = x.Element("ArriveNo").Value,
                 Title = x.Element("Title").Value,
                 ProviderID = x.Element("ProviderName").Value,
                 Purchaser = x.Element("Purchaser").Value,
                 ProductNo = x.Element("ProductNo").Value,
                 ProductName = x.Element("ProductName").Value,
                 ColorName = x.Element("ColorName").Value,
                 
                 TotalPrice = x.Element("TotalPrice").Value,
                 ProductCount = x.Element("ProductCount").Value,
                 InCount = x.Element("InCount").Value,
                 DetailID = x.Element("DetailID").Value,
                 UnitName = x.Element("UnitName").Value,
                 JiBenCount = x.Element("JiBenCount").Value,
                 UnitPrice = IsDisplayPrice ? x.Element("UnitPrice").Value : "0.000000"

             })
                      :
            (from x in dsXML.Descendants("Data")
             orderby x.Element(orderBy).Value descending
             select new DataSourceModel()
             {
                 ID = x.Element("ID").Value,
                 ArriveNo = x.Element("ArriveNo").Value,
                 Title = x.Element("Title").Value,
                 ProviderID = x.Element("ProviderName").Value,
                 Purchaser = x.Element("Purchaser").Value,
                 ProductNo = x.Element("ProductNo").Value,
                 ProductName = x.Element("ProductName").Value,
                 ColorName = x.Element("ColorName").Value,
                 
                 TotalPrice = x.Element("TotalPrice").Value,
                 ProductCount = x.Element("ProductCount").Value,
                 InCount = x.Element("InCount").Value,
                 DetailID = x.Element("DetailID").Value,
                 UnitName = x.Element("UnitName").Value,
                 JiBenCount = x.Element("JiBenCount").Value,
                 UnitPrice = IsDisplayPrice ? x.Element("UnitPrice").Value : "0.000000"
             });
        int totalCount = dsLinq.Count();

　　dsLinq.Count() 引发了“System.NullReferenceException”类型的异常,其中任何字段都不能为null

转载于:https://www.cnblogs.com/Jeremy2001/p/9124290.html