Renaming array items in a flat xml array using an XmlSerializer

Question

I have an XML file with the following format:

<?xml version="1.0" encoding="UTF-8"?>
<Items>
    <Item Property1="A" Property2="B" />
    <Item Property1="C" Property2="D" />
</Items>

I need to read the <Item> elements as objects of class MyClass using an XmlSerializer.

public class MyCLass
{
    [XmlAttribute]
    public string Property1 { get; set; }

    [XmlAttribute]
    public string Property2 { get; set; }
}

Currently, I have the following code to read the file:

XmlSerializer serializer =
    new XmlSerializer(typeof(MyClass[]), new XmlRootAttribute(@"Items"));

MyClass[] list = (MyClass[])serializer.Deserialize(...);

Since the element name <Item> is different from the class name MyCLass, the elements in the array are not deserialized at all. The above code works if I rename MyClass to Item, but unfortunately I am not allowed to change the XML file or the class names.

How do I go about mapping the two so that the file can be read correctly?

Thanks in advance!

score 4 · Accepted Answer · answered Dec 12 '10 at 00:21

Use a wrapper class that contains the array, this will allow you to apply the XmlElement attribute:

public class MyClassList
{
    [XmlElement("Item")]
    public MyClass[] Items { get; set; }
}

var items = new[]
{
    new MyClass { Property1 = "A", Property2 = "B" },
    new MyClass { Property1 = "C", Property2 = "D" },
};
var list = new MyClassList { Items = items };

using (var writer = new StringWriter())
{
    var xs = new XmlSerializer(typeof(MyClassList), new XmlRootAttribute("Items"));
    xs.Serialize(writer, list);
    writer.ToString().Dump();
}

I'm not so sure why it works though :-) I was running around after XmlArrayItem and XmlAttributeOverrides. Thanks again! — xmlWiz, Dec 12 '10 at 12:30

score 2 · Answer 2 · answered Dec 11 '10 at 19:47

Personally I would serialize and deserialize manually - I've found that it's easier to get whatever flexibility you want that way rather than spending a long time messing around with the built-in serialization and living with the various restrictions it imposes. LINQ to XML makes it pretty simple. For example, in this case:

XDocument doc = XDocument.Load("test.xml");
// You could use an array if you really wanted, of course.
List<MyClass> list = doc.Root
                        .Elements("Item")
                        .Select(x => new MyClass {
                            Property1 = (string) x.Attribute("Property1"),
                            Property2 = (string) x.Attribute("Property2"),
                         })
                        .ToList();

Admittedly this will get hairy if you need to serialize objects with complicated relationships (two objects referring to the same child or whatever) but I've had a great deal of success with it in the past.

Thanks for the tip! In my case, the actual MyClass structure is pretty complex, with nested hierarchies - so this approach could get a bit complicated... — xmlWiz, Dec 12 '10 at 12:33
@xmlWiz: If you follow a pattern with each class knowing how to deserialize and serialize itself, I've found it's not too bad - and easy to unit test. But if you have shared references etc, it does get complicated. — Jon Skeet, Dec 12 '10 at 12:39

Renaming array items in a flat xml array using an XmlSerializer

2 Answers2