Return XML from a controller's action in as an ActionResult?

Question

return this.Content(xmlString, "text/xml");

Use MVCContrib's XmlResult Action.

For reference here is their code:

public class XmlResult : ActionResult
{
    private object objectToSerialize;

    /// <summary>
    /// Initializes a new instance of the <see cref="XmlResult"/> class.
    /// </summary>
    /// <param name="objectToSerialize">The object to serialize to XML.</param>
    public XmlResult(object objectToSerialize)
    {
        this.objectToSerialize = objectToSerialize;
    }

    /// <summary>
    /// Gets the object to be serialized to XML.
    /// </summary>
    public object ObjectToSerialize
    {
        get { return this.objectToSerialize; }
    }

    /// <summary>
    /// Serialises the object that was passed into the constructor to XML and writes the corresponding XML to the result stream.
    /// </summary>
    /// <param name="context">The controller context for the current request.</param>
    public override void ExecuteResult(ControllerContext context)
    {
        if (this.objectToSerialize != null)
        {
            context.HttpContext.Response.Clear();
            var xs = new System.Xml.Serialization.XmlSerializer(this.objectToSerialize.GetType());
            context.HttpContext.Response.ContentType = "text/xml";
            xs.Serialize(context.HttpContext.Response.Output, this.objectToSerialize);
        }
    }
}

If you're building the XML using the excellent Linq-to-XML framework, then this approach will be helpful.

I create an XDocument in the action method.

public ActionResult MyXmlAction()
{
    // Create your own XDocument according to your requirements
    var xml = new XDocument(
        new XElement("root",
            new XAttribute("version", "2.0"),
            new XElement("child", "Hello World!")));

    return new XmlActionResult(xml);
}

This reusable, custom ActionResult serialises the XML for you.

public sealed class XmlActionResult : ActionResult
{
    private readonly XDocument _document;

    public Formatting Formatting { get; set; }
    public string MimeType { get; set; }

    public XmlActionResult(XDocument document)
    {
        if (document == null)
            throw new ArgumentNullException("document");

        _document = document;

        // Default values
        MimeType = "text/xml";
        Formatting = Formatting.None;
    }

    public override void ExecuteResult(ControllerContext context)
    {
        context.HttpContext.Response.Clear();
        context.HttpContext.Response.ContentType = MimeType;

        using (var writer = new XmlTextWriter(context.HttpContext.Response.OutputStream, Encoding.UTF8) { Formatting = Formatting })
            _document.WriteTo(writer);
    }
}

You can specify a MIME type (such as application/rss+xml) and whether the output should be indented if you need to. Both properties have sensible defaults.

If you need an encoding other than UTF8, then it's simple to add a property for that too.

If you are only interested to return xml through a request, and you have your xml "chunk", you can just do (as an action in your controller):

public string Xml()
{
    Response.ContentType = "text/xml";
    return yourXmlChunk;
}

There is a XmlResult (and much more) in MVC Contrib. Take a look at http://www.codeplex.com/MVCContrib

I've had to do this recently for a Sitecore project which uses a method to create an XmlDocument from a Sitecore Item and its children and returns it from the controller ActionResult as a File. My solution:

public virtual ActionResult ReturnXml()
{
    return File(Encoding.UTF8.GetBytes(GenerateXmlFeed().OuterXml), "text/xml");
}