Question

I have XML that is returned by a 3rd party web service in the following form:

<object>
    <list name="subscriptions">
        <object>
            <string name="id">something</string> 
            <string name="title">something else</string> 
            <list name="categories" /> 
            <number name="timestamp">1252707770116</number> 
        </object>
        ...more 'object'...
    </list>
</object>

I’m having a lot of issues trying to deserialize this data to an object. I wasn’t able to generate a schema using xsd.exe, so I generated the following classes by hand to try and fit this data:

[XmlRoot("object")]
public class ListOfSubscriptions
{
    [XmlElement("list")]
    public Subscription[] items;
}

[XmlRoot("object")]
public class Subscription
{
    [XmlAttribute()]
    public string id;
    [XmlAttribute()]
    public string title;
    [XmlAttribute()]
    public string[] categories;
    [XmlAttribute()]
    public string timestamp;
}

I’m trying to deserialize this with the following code:

XmlSerializer s = new XmlSerializer(typeof(ListOfSubscriptions));
StreamReader r = new StreamReader("out.xml");
ListOfSubscriptions listSubscribe = (ListOfSubscriptions)s.Deserialize(r);
r.Close();

However, when it finishes, listSubscribe has one member and all its fields are null.

How should I be creating my template for deserializing?

Thanks

Update – 2010/01/28

Thanks to everybody’s comments I’ve revised my classes to the following:

[XmlRoot("object")]
public class ListOfSubscriptions
{
    [XmlElement("list")]
    public SubscriptionList[] items;
}
[XmlRoot("list")]
public class SubscriptionList
{
    [XmlElement("object")]
    public Subscription[] items;
}

[XmlRoot("object")]
public class Subscription
{
    [XmlElement("string")]
    public string id;
    [XmlElement("string")]
    public string title;
    [XmlElement("list")]
    public string[] categories;
    [XmlElement("number")]
    public string timestamp;
}

If I comment out the [XmlElement(…)] lines in Subscription, and run, I get that listSubscribe has one SubscriptionList item which has the correct number of Subscriptions, however, all the elements of the subscriptions are null.

If I uncomment the XmlElement lines, I get an error reflecting a Subscription. I imagine its getting confused because there are multiple elements with the same name.

How do I tie the attribute name to the class member?

Answer 1

You’re on the right track. However, you are only defining two classes. There are actually three classes to define:

1. The single root object, with an XML name of “object”. This will have only one member:
2. The list of objects (with an XML name of “list”). This will have one member, an array of:
3. Subscriptions, with an XML name of “object”.

Another problem is that you are defining the Subscription fields as attributes. They aren’t attributes, they’re elements.