将Linq to Xml与Xml命名空间一起使用

Question

我有这个代码:

/*string theXml =
@"<Response xmlns=""http://myvalue.com""><Result xmlns:a=""http://schemas.datacontract.org/2004/07/My.Namespace"" xmlns:i=""http://www.w3.org/2001/XMLSchema-instance""><a:TheBool>true</a:TheBool><a:TheId>1</a:TheId></Result></Response>";*/

string theXml = @"<Response><Result><TheBool>true</TheBool><TheId>1</TheId></Result></Response>";

XDocument xmlElements = XDocument.Parse(theXml);

var elements = from data in xmlElements.Descendants("Result")
               select new {
                            TheBool = (bool)data.Element("TheBool"),
                            TheId = (int)data.Element("TheId"),
                          };

foreach (var element in elements)
{
    Console.WriteLine(element.TheBool);
    Console.WriteLine(element.TheId);
}

当我使用第一个值为xml时,结果为null,而对于第二个值,我有很好的值...

如何使用xmlns值将Linq用于Xml？

Answer 1

LINQ to XML方法喜欢Descendants并将Element其XName作为参数.有一个从转换string到XName时自动发生的事情给你.您可以通过XNamespace在Descendants和Element调用中添加字符串来解决此问题.请注意,因为您有两个不同的命名空间.

string theXml =
                @"true1";

            //string theXml = @"true1";

    XDocument xmlElements = XDocument.Parse( theXml );
    XNamespace ns = "http://myvalue.com";
    XNamespace nsa = "http://schemas.datacontract.org/2004/07/My.Namespace";
    var elements = from data in xmlElements.Descendants( ns + "Result" )
          select new
                 {
                     TheBool = (bool) data.Element( nsa + "TheBool" ),
                     TheId = (int) data.Element( nsa + "TheId" ),
                 };

    foreach ( var element in elements )
    {
        Console.WriteLine( element.TheBool );
        Console.WriteLine( element.TheId );
    }

注意使用ns in Descendants和nsaElements

Answer 2

您可以将带有命名空间的XName传递给Descendants()和Element().将字符串传递给Descendants()时,它会隐式转换为没有名称空间的XName.

要在命名空间中创建XName,请创建XNamespace并将其连接到元素local-name(字符串).

XNamespace ns = "http://myvalue.com";
XNamespace nsa = "http://schemas.datacontract.org/2004/07/My.Namespace";

var elements = from data in xmlElements.Descendants( ns + "Result")
                   select new
                              {
                                  TheBool = (bool)data.Element( nsa + "TheBool"),
                                  TheId = (int)data.Element( nsa + "TheId"),
                              };

还有一种简写形式,用于通过从字符串的隐式转换来创建具有命名空间的XName.

var elements = from data in xmlElements.Descendants("{http://myvalue.com}Result")
                   select new
                              {
                                  TheBool = (bool)data.Element("{http://schemas.datacontract.org/2004/07/My.Namespace}TheBool"),
                                  TheId = (int)data.Element("{http://schemas.datacontract.org/2004/07/My.Namespace}TheId"),
                              };

或者,您可以查询XElement.Name.LocalName.

var elements = from data in xmlElements.Descendants()
                   where data.Name.LocalName == "Result"