detect if an ASCX/ASPX is running in SharePoint?

Question

We have a set of code that is going to be used in both standalone ASP.NET and SharePoint. I'm wondering if there's any legitimate way to write conditional code in the CS file to detect whether SharePoint is present?

It needs to be able to run in or before OnPreInit, because based on this decision we'll be switching the MasterPageFile attribute, and that needs to be done early in the page lifecycle.

I suppose I can do something like checking for the existence of a "~/layouts" directory, etc. but there must be a better way to do this. And besides, who knows - for compatibility reasons (location of images, etc) we might actually adopt the SharePoint directory structure in the ASP.NET standalone mode.

It's okay to require the Microsoft.SharePoint.DLL even if it goes mostly unused when running standalone.

Thanks!

Answer 1

Since you are allowed to reference Microsoft.SharePoint:

using Microsoft.SharePoint;
// ...

if (SPContext.Current == null)
    // Not running in SharePoint
else
    // Running in SharePoint

Edit -- alternate approach taking NullReferenceException into consideration:

bool runningInSharePoint = false;
try
{
    if (SPContext.Current != null)
        runningInSharePoint = true;
}
catch (NullReferenceException e)
{
    // SharePoint is not present on the system
}

The above assumes that the exception you mentioned is thrown when accessing SPContext, not earlier.

Answer 2

I wonder if you are better off not including the SharePoint dll in your straight ASP.NET code. If you partial/sub class the SharePoint bit and include two build targets, you should be able to tack on the extra code needed for SharePoint without turding up your ASP.NET build.