Question

从调试我可以检查Stream正在传递

<POS>
  <Id>4</Id>
  <FolderPath>C://FolderPath</FolderPath>
  <Number>44</Number>
  <POSTillTypeRecord>Tilltype</POSTillTypeRecord>
  <StockLocationRecord>StockLocationRec</StockLocationRecord>
</POS>

为：

public XmlActionResult Upload()
    {
        //List<POSUnitRecord> POSs = null;

        try
        {
            using (var up = new StreamReader(Request.InputStream))
            {   

                POSUnitRecord POS =
                        (
                               from e in XDocument.Load(up).Root.Elements("Payment")  //POS")
                               //select (string)e.Element("POS")                                  
                               select new POSUnitRecord
                               {
                                   Id = Int32.Parse((string)e.Element("Id")),
                                   FolderPath = (string)e.Element("FolderPath"),
                                   Number = Int32.Parse((string)e.Element("Number")),

                                   //POSTillTypeRecord = (string)e.Element("POSTillTypeRecord"),
                                   //StockLocationRecord = (string)e.Element("StockLocationRecord")                                   
                               }
                           ).FirstOrDefault();

为什么POSUnitRecord POS返回NULL。付款/ POS有什么关系？

Answer 1

您的XML在root下没有Payment个元素。所以你有空序列。从空序列中获取FirstOrDefault()会为您提供null。

我建议您直接将xml加载到XElement中：

var p = XElement.Load(reader);
var pos = new POSUnitRecord
{
    Id = (int)p.Element("Id"),
    FolderPath = (string)p.Element("FolderPath"),
    Number = (int)p.Element("Number")
};

附注 - 您可以在此处使用Xml序列化：

[XmlRoot("POS")]
public class POSUnitRecord
{
    public int Id { get; set; }
    public string FolderPath { get; set; }
    public int Number { get; set; }
}

反序列化很简单：

using (var reader = new StreamReader(Request.InputStream))
{
    XmlSerializer serializer = new XmlSerializer(typeof(POSUnitRecord));
    var pos = (POSUnitRecord)serializer.Deserialize(reader);
}

Answer 2

您选择的“付款”元素不存在，但有一个“POS”元素。此外，该元素变为Root。最后，不需要使用Linq语法;您可以使用XLinq提供的方法：

var xDoc = XDocument.Load(up);
var posUnitRecords = xDoc.Root.Select(e => new POSUnitRecord()
{
    Id = Int32.Parse((string)e.Element("Id").Value),
    FolderPath = (string)e.Element("FolderPath").Value,
    Number = Int32.Parse((string)e.Element("Number").Value),

});
var firstRecord = POSUnitRecords.First();

xDocument.Load返回null？

2 个答案: