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

Question

What is the best way to return XML from a controller's action in ASP.NET MVC? There is a nice way to return JSON, but not for XML. Do I really need to route the XML through a View, or should I do the not-best-practice way of Response.Write-ing it?

Answer 1

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

Answer 2

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);
        }
    }
}

Answer 3

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.

Answer 4

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;
}

Answer 5

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

Answer 6

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");
}

Answer 7

use one of these methods

    public ContentResult GetXml()
    {
        string xmlString  = "your xml data";
        return Content(xmlString, "text/xml");
    }

or

    public string GetXml()
    {
        string xmlString = "your xml data";
        Response.ContentType = "text/xml";
        return xmlString;
    }

Answer 8

Finally manage to get this work and thought I would document how here in the hopes of saving others the pain.

Environment

• VS2012
• SQL Server 2008R2
• .NET 4.5
• ASP.NET MVC4 (Razor)
• Windows 7

Supported Web Browsers

• FireFox 23
• IE 10
• Chrome 29
• Opera 16
• Safari 5.1.7 (last one for Windows?)

My task was on a ui button click, call a method on my Controller (with some params) and then have it return an MS-Excel XML via an xslt transform. The returned MS-Excel XML would then cause the browser to popup the Open/Save dialog. This had to work in all the browsers (listed above).

At first I tried with Ajax and to create a dynamic Anchor with the "download" attribute for the filename, but that only worked for about 3 of the 5 browsers(FF, Chrome, Opera) and not for IE or Safari. And there were issues with trying to programmatically fire the Click event of the anchor to cause the actual "download".

What I ended up doing was using an "invisible" IFRAME and it worked for all 5 browsers!

So here is what I came up with: [please note that I am by no means an html/javascript guru and have only included the relevant code]

HTML (snippet of relevant bits)

<div id="docxOutput">
<iframe id="ifOffice" name="ifOffice" width="0" height="0"
    hidden="hidden" seamless='seamless' frameBorder="0" scrolling="no"></iframe></div>

JAVASCRIPT

//url to call in the controller to get MS-Excel xml
var _lnkToControllerExcel = '@Url.Action("ExportToExcel", "Home")';
$("#btExportToExcel").on("click", function (event) {
    event.preventDefault();

    $("#ProgressDialog").show();//like an ajax loader gif

    //grab the basket as xml                
    var keys = GetMyKeys();//returns delimited list of keys (for selected items from UI) 

    //potential problem - the querystring might be too long??
    //2K in IE8
    //4096 characters in ASP.Net
    //parameter key names must match signature of Controller method
    var qsParams = [
    'keys=' + keys,
    'locale=' + '@locale'               
    ].join('&');

    //The element with id="ifOffice"
    var officeFrame = $("#ifOffice")[0];

    //construct the url for the iframe
    var srcUrl = _lnkToControllerExcel + '?' + qsParams;

    try {
        if (officeFrame != null) {
            //Controller method can take up to 4 seconds to return
            officeFrame.setAttribute("src", srcUrl);
        }
        else {
            alert('ExportToExcel - failed to get reference to the office iframe!');
        }
    } catch (ex) {
        var errMsg = "ExportToExcel Button Click Handler Error: ";
        HandleException(ex, errMsg);
    }
    finally {
        //Need a small 3 second ( delay for the generated MS-Excel XML to come down from server)
        setTimeout(function () {
            //after the timeout then hide the loader graphic
            $("#ProgressDialog").hide();
        }, 3000);

        //clean up
        officeFrame = null;
        srcUrl = null;
        qsParams = null;
        keys = null;
    }
});

C# SERVER-SIDE (code snippet) @Drew created a custom ActionResult called XmlActionResult which I modified for my purpose.

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

My Controller method (returns ActionResult)

• passes the keys parameter to a SQL Server stored proc that generates an XML
• that XML is then transformed via xslt into an MS-Excel xml (XmlDocument)

• creates instance of the modified XmlActionResult and returns it

  XmlActionResult result = new XmlActionResult(excelXML, "application/vnd.ms-excel"); string version = DateTime.Now.ToString("dd_MMM_yyyy_hhmmsstt"); string fileMask = "LabelExport_{0}.xml";
  result.DownloadFilename = string.Format(fileMask, version); return result;

The main modification to the XmlActionResult class that @Drew created.

public override void ExecuteResult(ControllerContext context)
{
    string lastModDate = DateTime.Now.ToString("R");

    //Content-Disposition: attachment; filename="<file name.xml>" 
    // must set the Content-Disposition so that the web browser will pop the open/save dialog
    string disposition = "attachment; " +
                        "filename=\"" + this.DownloadFilename + "\"; ";

    context.HttpContext.Response.Clear();
    context.HttpContext.Response.ClearContent();
    context.HttpContext.Response.ClearHeaders();
    context.HttpContext.Response.Cookies.Clear();
    context.HttpContext.Response.Cache.SetCacheability(System.Web.HttpCacheability.NoCache);// Stop Caching in IE
    context.HttpContext.Response.Cache.SetNoStore();// Stop Caching in Firefox
    context.HttpContext.Response.Cache.SetMaxAge(TimeSpan.Zero);
    context.HttpContext.Response.CacheControl = "private";
    context.HttpContext.Response.Cache.SetLastModified(DateTime.Now.ToUniversalTime());
    context.HttpContext.Response.ContentType = this.MimeType;
    context.HttpContext.Response.Charset = System.Text.UTF8Encoding.UTF8.WebName;

    //context.HttpContext.Response.Headers.Add("name", "value");
    context.HttpContext.Response.Headers.Add("Last-Modified", lastModDate);
    context.HttpContext.Response.Headers.Add("Pragma", "no-cache"); // HTTP 1.0.
    context.HttpContext.Response.Headers.Add("Expires", "0"); // Proxies.

    context.HttpContext.Response.AppendHeader("Content-Disposition", disposition);

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

That was basically it. Hope it helps others.

Answer 9

A simple option that will let you use streams and all that is return File(stream, "text/xml");.

Answer 10

Here is a simple way of doing it:

        var xml = new XDocument(
            new XElement("root",
            new XAttribute("version", "2.0"),
            new XElement("child", "Hello World!")));
        MemoryStream ms = new MemoryStream();
        xml.Save(ms);
        return File(new MemoryStream(ms.ToArray()), "text/xml", "HelloWorld.xml");

Answer 11

A small variation of the answer from Drew Noakes that use the method Save() of XDocument.

public sealed class XmlActionResult : ActionResult
{
    private readonly XDocument _document;
    public string MimeType { get; set; }

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

        _document = document;

        // Default values
        MimeType = "text/xml";
    }

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