File download issue with api controller

Question

public class DefaultController : Controller
{
    // GET: Default
    public ActionResult Index()
    {
        return Download();
    }

    public FileResult Download()
    {
        string xmlString = "my test xml data";
        string fileName = "test" + ".xml";
        return File(Encoding.UTF8.GetBytes(xmlString), "application/xml", fileName);
    }
}

I have the above code in asp.net mvc application to download a file. It worked fine as my controller is inherited to Controller. But when I move this code to Webapi controller it throws error at return File. After analysis I found that my controller in webapi is inheriting to ApiController(system.web.http.api controller). I found that there is no File class in ApiController. Is there any option to implement downloading file functionality in webapi controller?

I tried the below alternative code in webapi controller but couldnt see a downloading file once I call this.

public HttpResponseMessage DownloadConstructedXmlFile()
        {
            var result = new HttpResponseMessage(HttpStatusCode.OK);
            string xmlContent = "My test xml data";
            //var serializer = new XmlSerializer(typeof(xmlContent));

            var builder = new StringBuilder();
            using (var writer = new StringWriter(builder))
            {
                // serializer.Serialize(writer, xmlContent);
                result.Content = new StringContent(xmlContent, Encoding.UTF8, "application/xml");
                result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
                {
                    FileName = string.Format("test.xml")
                };
               // return result;
            }

            return new HttpResponseMessage();
        }

PS: I am trying to use angularjs code to call this api through angular service.This is invoked on download button click. Any sample angular code or help in api controller code or suggestions would be helpful.

Answer 1

It think something like this would do the trick!

public HttpResponseMessage Get(string fileName)
{
    FileStream fileStream = FileProvider.Open(fileName);
    var response = new HttpResponseMessage();
    response.Content = new StreamContent(fileStream);
    response.Content.Headers.ContentDisposition 
                      = new ContentDispositionHeaderValue("attachment");
    response.Content.Headers.ContentDisposition.FileName = fileName;
    response.Content.Headers.ContentType
                     = new MediaTypeHeaderValue("application/octet-stream");
    response.Content.Headers.ContentLength 
                     = FileProvider.GetLength(fileName);
    return response;
}

Answer 2

Considering you're are returning XML you could have the controller return an XDocument.

public XDocument returnXMLFile()
{
   var xDoc = XDocument.Load("test.xml");
   return xDoc;
}

You will then either need to modify GlobalConfiguration.Configuration.Formatters to return XML, or configure your client to set the accept header to application/xml

One way to configure the server to return XML over another type like JSON, is the following code:

var xml = new System.Net.Http.Formatting.XmlMediaTypeFormatter();
xml.MediaTypeMappings.Add(new QueryStringMapping("format", "xml", "application/xml"));
GlobalConfiguration.Configuration.Formatters.Add(xml);

You could then download the file as xml via a hyperlink

<a href="[pathToController]/returnxmlfile?format=xml" >Download XML</a>

To customise have a look at these questions about downloading a file with Angular js.

• Download file from a ASP.NET Web API method using angularjs
• download csv file from web api in angular js

Answer 3

Here is a much simpler example:

   using System.Net;
   using System.Net.Http;
   using System.Net.Http.Headers;
   using System.Text;
   using System.Web.Http;

   namespace WebApplication1.Controllers
   {
    public class ValuesController : ApiController
    {
        // GET: api/Values
        public HttpResponseMessage Get()
        {
            var xmlString = "<xml><name>Some XML</name></xml>";
            var result = Request.CreateResponse(HttpStatusCode.OK);
            result.Content = new StringContent(xmlString, Encoding.UTF8, "application/xml");
            result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
            {
                FileName = "test.xml"
            };

            return result;
        }
    }
   }