deserialize xml in complex object

问题:

I can't understand why object is null:

        WebClient browse = new WebClient();
        StreamReader res = new StreamReader(browse.OpenRead("http://ws.audioscrobbler.com/2.0/?method=track.getinfo&api_key=b25b959554ed76058ac220b7b2e0a026&artist=cher&track=believe"));
        string result = res.ReadToEnd();

        XmlDocument xmltrackinfo = new XmlDocument();
        xmltrackinfo.InnerXml = result;



        XmlRootAttribute xRoot = new XmlRootAttribute();
        xRoot.ElementName = "lfm";
        xRoot.IsNullable = true;

        XmlSerializer xs = new XmlSerializer(typeof(fm), xRoot);

        fm rez = (fm) xs.Deserialize(new MemoryStream(Encoding.UTF8.GetBytes(result)));

Object Model:

[Serializable()]
[XmlRoot(ElementName = "lfm", IsNullable = true)]
public class fm
{
    [XmlElement("lfm")]
    public Track lfm { get; set; }
}

[Serializable()]
[XmlRoot(ElementName = "artist", IsNullable = true)]
public class artist
{
    public string name { get; set; }
    public string mbid { get; set; }
    public string url { get; set; }
}

[Serializable()]
[XmlRoot(ElementName = "album", IsNullable = true)]
public class album
{
    public string artist { get; set; }
    public string title { get; set; }
    public string mbid { get; set; }
    public string url { get; set; }
    public List<string> image { get; set; }
}

[Serializable()]
[XmlRoot(ElementName = "tag", IsNullable = true)]
public class tag
{
    public string name { get; set; }
    public string url { get; set; }

}

[Serializable()]
[XmlRoot(ElementName = "wiki", IsNullable = true)]
public class wiki
{
    public string summary { get; set; }
    public string content { get; set; }
}

[Serializable()]
[XmlRoot(ElementName = "track", IsNullable = true)]
public class Track
{
    public string id { get; set; }
    public string name { get; set; }
    public string mbid { get; set; }
    public string url { get; set; }
    public string duration { get; set; }
    public string streamable { get; set; }
    public string listeners { get; set; }
    public string playcount { get; set; }
    public artist artist { get; set; }
    public album album { get; set; }
    public List<tag> toptags { get; set; }
    public wiki wiki { get; set; }

}

and XML:

http://ws.audioscrobbler.com/2.0/?method=track.getinfo&api_key=b25b959554ed76058ac220b7b2e0a026&artist=cher&track=believe

so what should I do?

回答1:

Try renaming your fm class to lfm.

public class lfm
{
    public Track track { get; set; }
}

and then you could also get rid of the xRoot variable:

XmlSerializer xs = new XmlSerializer(typeof(lfm));
lfm rez = (lfm) xs.Deserialize(new MemoryStream(Encoding.UTF8.GetBytes(result)));

Also you don't need the [Serializable] attribute. This is used for binary serialization and is completely ignored by the XmlSerializer class.

回答2:

The lfm property of the fm class must have track as its XmlElement:

[Serializable()]
[XmlRoot(ElementName = "lfm", IsNullable = true)]
public class fm
{
    [XmlElement("track")]
    public Track lfm { get; set; }
}