How can I upload files asynchronously on ASP.NET ?

Question

I've been looking for a way to achieve this behavior and I found this sample project.

The trick in this project is that it changes the form target to an iframe created on the fly.

So far so good, I can get the byte[] on the server-side. But I need to change an image preview after the file is uploaded.

How can I get the iframe to update the main page? Would I have to save it on a file on the disk, make a javascript callback to change the image url? Is there another way to do this? What's recommended?

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This control suggested by vorrtex actually causes a full page postback, am I missing something or is it the correct behavior?

Answer 1

Add a <script> block to the page that gets loaded in the <iframe> that interacts with the parent page and updates whatever you need to.

Answer 2

I recommend you to use AsyncFileUploader and UpdatePanel. You have to save file on the disk but you can use C# for changing imageUrl.

Answer 3

Visit This link for creating an asynchronous file uploader in asp.net