Question

I’m obtaining an image from Google Charts by making a WebRequest via POST.

The problem I’m having is displaying the image returned by Google.

I can see in Fiddler that the request for the image is made, and the image returned in the response when I do:

var response = request.GetResponse();

However from here I don’t seem to be able to output the image from my controller.

Here’s what I’m doing right now:

using (var dataStream = response.GetResponseStream())
            {
                if (dataStream == null) return;

                using (var reader = new StreamReader(dataStream))
                {
                    byte[] dataBytes = Encoding.UTF8.GetBytes(reader.ReadToEnd());
                    Response.ContentType = "image/png";
                    Response.BinaryWrite(dataBytes);
                }
            }

The error message displayed in my browser window is:

The image “[path to image]” cannot be displayed, because it contains
errors.

Answer 1

Try using a WebClient, it will simplify your code:

public ActionResult MyChart()
{
    using (var client = new WebClient())
    {
        var data = client.DownloadData("http://......");

        // TODO: the MIME type might need adjustment
        return File(data, "image/png", "chart.png"); 
    }
}

or if you need to use a POST request and send some values use the UploadValues method:

public ActionResult MyChart()
{
    using (var client = new WebClient())
    {
        var request = new NameValueCollection
        {
            { "foo", "foo value" },
            { "bar", "bar value" },
        };
        var data = client.UploadValues("http://......", request);

        // TODO: the MIME type might need adjustment
        return File(data, "image/png", "chart.png"); 
    }
}

and then in the view:

<img src="@Url.Action("MyChart", "SomeController")" alt="chart" />

or if the url is static and could be reached with a GET request you could directly include it in your view (you don’t need a controller action in this case):

<img src="http://......" alt="chart" />