我有以下类型的XML：

I am having following type of XML:

通过这个XML我想填充以下链表。

Through this XML I wish to populate following objectList.

List<Function> objFunctionsList = new List<Function>();

，其中Function类的有：

where Function class is as follows,

public class Function
{
    public String Name { get ; set; }
    public Parameter ReturnType { get; set; }
    public List<Parameter> Parameters { get; set; }
    public String Library { get; set; }
    public String Signature { get; set; }
    public String Description { get; set; }
    public String Code { get; set; }
}

和参数类，如下所示，

public class Parameter
{
    [DefaultValue("")] 
    public String Name { get; set; }

    [DefaultValue("")]
    public String DataType { get; set; }

    [DefaultValue("")]
    public String OccurenceType { get; set; }
}

您可以看到，在一些XML标签功能有参数的标签，而有些则没有。我曾尝试这样的：

You can see that in XML some function tags have Parameters tag while some others do not. I have tried this:

public const string XPATH_NAME = "/Functions/Function/Name";
public const string XPATH_LIBRARY = "/Functions/Function/Library";
public const string XPATH_SIGNATURE = "/Functions/Function/Signature";
public const string XPATH_DESCRIPTION = "/Functions/Function/Description";
public const string XPATH_CODE = "/Functions/Function/Code";

List<Function> objFunctionsList = new List<Function>();

try
{
    XmlDocument xmlDoc = new XmlDocument();
    xmlDoc.Load(pXMLPath);

    XmlNodeList nlName = xmlDoc.SelectNodes(Constants.XPATH_NAME);
    XmlNodeList nlLibrary = xmlDoc.SelectNodes(Constants.XPATH_LIBRARY);
    XmlNodeList nlSignature = xmlDoc.SelectNodes(Constants.XPATH_SIGNATURE);
    XmlNodeList nlDescription = xmlDoc.SelectNodes(Constants.XPATH_DESCRIPTION);
    XmlNodeList nlCode = xmlDoc.SelectNodes(Constants.XPATH_CODE);

    // Name, Signature, Library, element should be present in 'Function' node
    if (nlName.Count == nlLibrary.Count
        && nlName.Count == nlSignature.Count
        && nlName.Count == nlDescription.Count
        && nlName.Count == nlCode.Count)
    {
        for (int iCount = 0; iCount < nlName.Count; iCount++)
        {
            Function objFunction = new Function();
            objFunction.Name = nlName[iCount].InnerText.Trim();
            objFunction.Library = nlLibrary[iCount].InnerText.Trim();
            string signature = nlSignature[iCount].InnerText;

            Parameter objReturnType = new Parameter();
            string returnType = (nlSignature[iCount].Attributes[Constants.ATRR_TYPE] == null
                ? Constants.XSNOPARAM
                : nlSignature[iCount].Attributes[Constants.ATRR_TYPE].Value);

            if (returnType.EndsWith(Constants.ASTERIK))
            {
                objReturnType.DataType = returnType.Substring(0, returnType.Length - 1);
                objReturnType.OccurenceType = Constants.OCCURENCES_ASTERISK;
            }
            else if (returnType.EndsWith(Constants.PLUS))
            {
                objReturnType.DataType = returnType.Substring(0, returnType.Length - 1);
                objReturnType.OccurenceType = Constants.OCCURENCES_PLUS;
            }
            else if (returnType.EndsWith(Constants.QUESTION_MARK))
            {
                objReturnType.DataType = returnType.Substring(0, returnType.Length - 1);
                objReturnType.OccurenceType = Constants.OCCURENCES_QUESTION;
            }
            else if (returnType.Length > 0)
            {
                objReturnType.DataType = returnType;
            }

            objFunction.ReturnType = objReturnType;

            objFunction.Parameters = new List<Parameter>();

            objFunction.Signature = signature;
            objFunction.Description = nlDescription[iCount].InnerText.Trim();
            objFunction.Code = nlCode[iCount].InnerText.Trim();

            objFunctionsList.Add(objFunction);
        }
    }
}

但这是基于XPath的code和是在使用更早的时候，我没有在函数变量参数标签。

but this is XPath based code and was in use earlier when I was not having Parameters Tag in the function tag.

推荐答案

检查，看看是否这会有所帮助 - http://blogs.msdn.com/b/ericwhite/archive/2009/05/14/working-with-optional-elements-and-attributes-in-linq-to-xml-queries.aspx

Check this and see if this helps - http://blogs.msdn.com/b/ericwhite/archive/2009/05/14/working-with-optional-elements-and-attributes-in-linq-to-xml-queries.aspx