Question

I have a controller like this:

public ActionResult Upload (int id, HttpPostedFileBase uploadFile)
{
....
}

How can I make sure that uploadFile is an image (jpg, png etc.)

I have tried with

using (var bitmapImage = new Bitmap (uploadFile.InputStream)) {..}

which throws an ArgumentException if bitmapImage can not be created.

Is there a better way for example by looking at uploadFile.FileName?

Answer 1

You can check the HttpPostedFileBase object’s properties for this

• ContentType
• FileName (check the file extensions, which you already know about 🙂 )

Also here is a small method, I have prepared which you can use/extend…

private bool IsImage(HttpPostedFileBase file)
{
    if (file.ContentType.Contains("image"))
    {
        return true; 
    }

    string[] formats = new string[] { ".jpg", ".png", ".gif", ".jpeg" }; // add more if u like...

    // linq from Henrik Stenbæk
    return formats.Any(item => file.FileName.EndsWith(item, StringComparison.OrdinalIgnoreCase));
}

I have also written an article on this here