How to use XML files as content files in XNA?

Question

I have an XML file representing different car manufactures that will be available in my game. The file looks like this:

<?xml version="1.0" encoding="utf-8" ?>
<XnaContent>
  <Asset Type="List[string]">
    <car>Audi</car>
    <car>BMW</car>
    <car>Nissan</car>
    <car>Volvo</car>
  </Asset>
</XnaContent>

When adding it into my content folder, the compiler return this error:

There was an error while deserializing intermediate XML. Cannot find type "List`1"

How can I create a list of strings, put it into XML and read it from XNA?

Answer 1

I haven't tried to find out exactly what is wrong with your XML - it's probably the lack of a namespace. But here is the correct XML:

<?xml version="1.0" encoding="utf-8"?>
<XnaContent xmlns:Generic="System.Collections.Generic">
  <Asset Type="Generic:List[string]">
    <Item>Audi</Item>
    <Item>BMW</Item>
    <Item>Nissan</Item>
    <Item>Volvo</Item>
  </Asset>
</XnaContent>

Under the hood the XmlImporter uses the IntermediateSerializer class. So a small program like the following can be used to determine what your XML should look like:

var test = new List<string>(){ "Audi", "BMW", "Nissan", "Volvo" };
var sb = new StringBuilder();
using(XmlWriter writer = XmlWriter.Create(sb))
{
    IntermediateSerializer.Serialize(writer, test, null);
}
Console.Write(sb.ToString());

(You can even convert the output to a stream, pass it to the Deserialize method, and reconstruct the object - just to be doubly-sure it's working. Also it is probably worth putting the right encoding in the header - eg: StringBuilder is utf-16.)

For some in-depth information about IntermediateSerializer, take a look at Shawn Hargreaves' blog, starting with this post and continuing through the archives until August 2008.

Answer 2

If you want to see how to do it by code example, here is a sample that uses xml like you want to http://create.msdn.com/en-US/education/catalog/sample/collision

If you want to read articles explaining whats going on and gain insight on how to work with xml & the content processor, go to this link, scroll down to the intermediate serializer section and read the 8 or 9 articles there. http://www.talula.demon.co.uk/blogindex.html