As far as I know, manually editing a context's designer.cs file doesn't work.  Any event (such as moving an entity on the context's designer) causes designer.cs to re-generate wiping out your manual edits.

 

So, code with dependencies on the attached [DataType(DataType.PhoneNumber)] will break as soon as the context is modified.  I tested this behavior using a LINQ to SQL context.  Is there a way to prevent manual edits from being wiped out?

 

Cody Skidmore