SharePoint Sandbox: How to specify the solution ID

When creating solutions for the SharePoint sandbox, whether it is for SharePoint 2010 or Office365, the solution ID must be given whenever some kind of code-behind is used. This is because SharePoint needs to know which assembly to use. Without the solution ID SharePoint would just look in the GAC for the assembly, which would produce a 'File could not be found' exception.

I will show how to supply the solution ID for a number of SharePoint components, and also describe a work-around in a case where we cannot specify a solution ID.

How to update the assembly in sandboxed solutions

Sometimes we need to make changes to the assembly in a deployed SharePoint 2010 sandboxed solution. Perhaps we need to add something in an event receiver. Or perhaps we added a bug fix (not relevant - the code always works). Or some custom webpart needs to do something else than what it is doing right now.

The only problem is that the solution is deployed in a production environment. We can't just delete and recreate the site, then add the updated solution package, and then tell the users to start all over. So what do we do?

Not to worry: This is a piece of cake - and a small piece at that.