Using ASP.NET Server Controls in MVC?

Question

On my current project I need to add a functionality that allows the user to view a thumbnail of their uploaded PDF. I've found a handy component that achieves this (the basic version is free, but it's enough for my current needs). Anyways, the control is pretty outdated (2010), therefore there doesn't seem to be MVC support. On the demos they depict usage of the control as such:

The View's Markup:

<form method="post" runat="server" enctype="multipart/form-data">
       <asp:Panel ID="thumbnailsPanel" runat="server" />
</form>

The thumbnail control is instantiated via code, the byte array which represents the thumbnail is passed to the control and the control is added to thumbnailsPanel

<script runat="server">
protected void DisplayThumbs_Click( object sender, System.EventArgs e )
{
      Thumbnail thumbnail = new Thumbnail();
      thumbnail.SessionKey = sessionID;
      thumbnail.Index = i;
      thumbnailsPanel.Controls.Add( thumbnail );
}
</script>

Given that I can't declare a Thumbnail control in my razor view, how would I used this control in MVC? I've spent a few hours trying to make this control MVC friendly to no avail, the best I've come up with is to include a .ASPX view (not.cshtml) in my project and render the Thumbnail control on that view. Obviously this is not desirable.

So how would you go about using a ASPX server controls in MVC? Is the idea a bad one altogether and should not be practised?

Something to think about: maybe try ImageMagick.NET or PDFSharp to convert to image, and GDI to convert the image to a PDF? By building a component as opposed to a web form control, you can access it within a controller. — bryanjonker
– bryanjonker, Commented Nov 15, 2012 at 21:06
Using GDI in an ASP.NET application is not supported by Microsoft, and you cannot "convert" an image to a PDF. — Dai
– Dai, Commented Nov 15, 2012 at 21:13
possible duplicate of Why can't I use server controls in ASP.net MVC? — jrummell
– jrummell, Commented Nov 15, 2012 at 21:25
@jrummel, thanks for your input, but I don't see how my question is a duplicate of the one you linked. I didn't ask "why can't server controls be used in MVC" or anything about the architecture of MVC, I asked about possible workarounds. So the question's aren't the same by a long shot. It doesn't really make sense for a new technology to downgrade the functionality(s) that were available on it's predecessor. — ms87
– ms87, Commented Nov 15, 2012 at 21:45

Dai · Accepted Answer · 2012-11-15 21:13:55Z

3

I worked around it in a project of mine by reimplementing the control as a HtmlHelper. Assuming the control isn't too complicated then it should work for you too. Do this:

Dump the Control's source using Reflector
Massage the source so it actually compiles (as source from Reflector doesn't usually compile straight away)
Identify what state the control has. Convert the state from member properties into members of its own new ViewModel class.
Find the Render method and convert it to a HtmlHelper that uses ViewContext.Writer

For example:

public class FooControl : Control {
    public String Message { get; set; }

    public override void Render(HtmlTextWriter wtr) {
        wtr.WriteLine("<p>");
        wtr.WriteLine( message );
        wtr.WriteLine("</p>");
    }
}

Becomes this:

public class FooViewModel {
    public String Message { get; set; }
}

// This method should exist in a static Extensions class for HtmlHelper
public static void Foo(this HtmlHelper html, FooViewModel model) {
    HtmlTextWriter wtr = html.ViewContext.Writer;
    wtr.WriteLine("<p>");
    wtr.WriteLine( model.Message );
    wtr.WriteLine("</p>");
}

edited Nov 15, 2012 at 21:13

answered Nov 15, 2012 at 20:58

Dai

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3 Comments

ms87 Over a year ago

Thanks. Any chance of a link to an example on how to do this?

ms87 Over a year ago

Are there any free reflector software's available? Can't seem to find one.

ms87 Over a year ago

I tried my hand at opening the dll with a reflector and modifying it, but it was far too confusing and beyond my expertise. A lot of weird unicode characters appeared across the code. Eventually I ended up just putting the component in a partial view (.ascx not .cshtml) and then used that partial view inside my main view. However using server controls in a MVC app is very un-MVC-ish I feel, which is why I'm accepting this answer as I believe this should be the standard way of doing it.

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