将子元素添加到XML中

您每次都要添加fields元素。这不是一个XML问题，而是一个逻辑问题。您的问题是在for循环中添加了"Fields"元素。构建所有元素，然后将它们全部添加到单个"Fields"元素中。或者，先构建fields元素，然后向其中添加子元素。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Linq;
namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(Sum2().ToString());
            Console.WriteLine();
            Console.WriteLine(Sum2Working().ToString());
            Console.Read();
        }
        public static XElement Sum2()
        {
            XNamespace defaultNamespace = XNamespace.Get("http://appserver.weevio.se/schema/SDKr1/Fields.xsd");
            XElement test = new XElement(new XElement(defaultNamespace + "FieldsRoot"));
            string value = "1694.152344;1694.092285;1693.972168;1693.852051";
            string datum = "2013-07-10 20:00:00;2013-07-10 19:00:00;2013-07-10 18:00:00;2013-07-10 17:00:00";
            string[] valueA = value.Split(';');
            string[] datumA = datum.Split(';');
            int d = 0;
            foreach (var customer in valueA)
            {
                XElement xElement = new XElement(defaultNamespace + "Numeric",
                        new XAttribute("value", valueA[d]),
                        new XAttribute("datum", datumA[d]),
                        new XAttribute("status", 16)
                );
                test.Add(new XElement(defaultNamespace + "Fields", new XAttribute("ok", "true"), new XAttribute("nodeId", "TEST.HW"), xElement));
                d = d + 1;
            }
            return test;
        }
        public static XElement Sum2Working()
        {
            XNamespace defaultNamespace = XNamespace.Get("http://appserver.weevio.se/schema/SDKr1/Fields.xsd");
            XElement test = new XElement(new XElement(defaultNamespace + "FieldsRoot"));
            string value = "1694.152344;1694.092285;1693.972168;1693.852051";
            string datum = "2013-07-10 20:00:00;2013-07-10 19:00:00;2013-07-10 18:00:00;2013-07-10 17:00:00";
            string[] valueA = value.Split(';');
            string[] datumA = datum.Split(';');
            int d = 0;
            var fields = new List<XElement>();
            foreach (var customer in valueA)
            {
                XElement xElement = new XElement(defaultNamespace + "Numeric",
                        new XAttribute("value", valueA[d]),
                        new XAttribute("datum", datumA[d]),
                        new XAttribute("status", 16)
                );
                fields.Add(xElement);
                d = d + 1;
            }
            test.Add(new XElement(defaultNamespace + "Fields", new XAttribute("ok", "true"), new XAttribute("nodeId", "TEST.HW"), fields));
            return test;
        }
    }
}

如您所见，Sum2Working（）将元素添加到列表中，然后将列表添加到较大的元素中。

您需要移动

test.Add(new XElement(defaultNamespace + "Fields", new XAttribute("ok", "true"), new XAttribute("nodeId", "TEST.HW"), xElement));

在foreach循环之外，以实现这一点。

尝试

[WebMethod]
public XElement Sum2()
{
XNamespace defaultNamespace = XNamespace.Get("http://appserver.weevio.se/schema/SDKr1/Fields.xsd");
XElement test = new XElement(new XElement(defaultNamespace + "FieldsRoot"));
string value = "1694.152344;1694.092285;1693.972168;1693.852051";
string datum = "2013-07-10 20:00:00;2013-07-10 19:00:00;2013-07-10 18:00:00;2013-07-10 17:00:00";
string[] valueA = value.Split(';');
string[] datumA = datum.Split(';');
int d = 0;
Xelement numericElement = new Xelement(); 
foreach (var customer in valueA)
{
    XElement xElement = new XElement(defaultNamespace + "Numeric",
            new XAttribute("value", valueA[d]),
            new XAttribute("datum", datumA[d]),
            new XAttribute("status", 16)
    );
    numericElement.Add(xElement);
    d = d + 1;
}
test.Add(new XElement(defaultNamespace + "Fields", new XAttribute("ok", "true"), new XAttribute("nodeId", "TEST.HW"), numericElement));
return test;

}