Cannot Convert System.String to System.Uri

Question

I am using the Web Client Class to download files from the internet (Flickr actually). This works fine as long as I use : WebClient().DownloadData(string) , however this locks up the UI as it is Not asynchronous.

However when I try WebClient().DownloadDatAsync(string), I get a compile error: "Unable to convert System.String to System.Uri".

The string MediumUrl returns "http://farm4.static.flickr.com/2232/2232/someimage.jpg"

So the question is how do I convert the string "http://farm4.static.flickr.com/2232/2232/someimage.jpg" to a Uri.

Things I have tried-

1. I have tried to cast it to Uri but that does not work either.

2. I have tried Uri myuri = new uri(string) - errors out as above.

   foreach (Photo photo in allphotos)  
   {  
       //Console.WriteLine(String.Format("photo title is :{0}", photo.Title));
       objimage = new MemoryStream(wc.DownloadData(photo.MediumUrl));
       images.Add(new Pictures(new Bitmap(objimage), photo.MediumUrl, photo.Title));  
   }
   

Answer 1

This works just fine;

System.Uri uri = new System.Uri("http://farm4.static.flickr.com/2232/2232/someimage.jpg");

By the way; I notice you mistyped the expression new uri(..., with lowercase uri. This is not your problem, is it? Because it should be "new Uri".

Answer 2

Okay, so I think if the others have proved your URI is valid in their code and it compiles etc. and you also mention it is generated at runtime - it could be that the UriString you are generating at runtime is invalid and not what you are expecting?

Instead of letting an exception be thrown for attempting to create a Uri from an invalid string, I would suggest the following method IsWellFormedUriString on the Uri class.

string uriString = "your_UriString_here";

if (Uri.IsWellFormedUriString(uriString, UriKind.Absolute))
{
    Uri uri = new Uri(uriString);
}
else
{
    Logger.WriteEvent("invalid uriString: " + uriString);
}

Might help with your debugging also.

Answer 3

objimage = new MemoryStream(wc.DownloadData(new Uri(photo.MediumUrl)));

b) I have tried Uri myuri = new uri(string) - errors out as above.

This is the usual way to create a Uri from a string... I don't see why it wouldn't work if the string is a valid URI