Question

Im new in C# and XML data ussage.

I’ve got the following xml data.
This XML file does not appear to have any style information associated with it. The document tree is shown below.

<response>
  <auctions>
   <auction>
    <id>90436</id>
    <user>blabla</user>
    <title>title name</title>
    <value>10000.00</value>
    <period>36</period>
    <www/>
   </auction>
   <auction>
    <id>90436</id>
    <user>blabla</user>
    <title>title name</title>
    <value>10000.00</value>
    <period>36</period>
    <www/>
   </auction>
  </auctions>
 </response>

I use that C# code. (it’s class used by Form1)

    public IXmlNamespaceResolver ns { get; set; }    

public string[] user,id,title,value,period;
    public void XmlRead(string url)
    {
                // Create a new XmlDocument  
                XPathDocument doc = new XPathDocument(url);
                // Create navigator  
                XPathNavigator navigator = doc.CreateNavigator();
                // Get forecast with XPath  
                XPathNodeIterator nodes = navigator.Select("/response/auctions", ns);

                int i = 0;
                foreach (XPathNavigator oCurrentPerson in nodes)
                {   
                    userName[i] = oCurrentPerson.SelectSingleNode("user").Value;
                    userId[i] = int.Parse(oCurrentPerson.SelectSingleNode("id").Value);
                    title[i] = oCurrentPerson.SelectSingleNode("title").Value;
                    value[i] = oCurrentPerson.SelectSingleNode("value").Value;
                    period[i] = oCurrentPerson.SelectSingleNode("period").Value;
                    i++; }
    }

Im getting an error:
Object reference not set to an instance of an object.

userName[i] = oCurrentPerson.SelectSingleNode(“user”).Value;

When I used single string variables like: userName, userId without [] everything worked correctly.

Thanks in advance

Answer 1

.Net is a strongly-typed world, so use it’s benefits. Create Auction class to hold data from your xml:

class Auction
{
    public int Id { get; set; }
    public string User { get; set; }
    public string Title { get; set; }
    public decimal Value { get; set; }
    public int Period { get; set; }
    public string Url { get; set; }
}

And parse your xml with Linq to Xml:

XDocument xdoc = XDocument.Load(path_to_xml_file);
IEnumerable<Auction> auctions =
    from a in xdoc.Descendants("auction")
    select new Auction()
    {
        Id = (int)a.Element("id"),
        User = (string)a.Element("user"),
        Title = (string)a.Element("title"),
        Value = (decimal)a.Element("value"),
        Period = (int)a.Element("period"),
        Url = (string)a.Element("www")
    };