Question

This does not seem to be explicitly listed as a feature in any of the sparse examples I can find, for example:

http://blogs.msdn.com/b/adonet/archive/2011/01/27/using-dbcontext-in-ef-feature-ctp5-part-1-introduction-and-model.aspx

http://www.codeproject.com/Articles/336187/code-first-practical-case

or

http://blogs.msdn.com/b/adonet/archive/2011/09/28/ef-4-2-code-first-walkthrough.aspx

But I think the DbContext docs at least imply that it’s possible:
http://msdn.microsoft.com/en-us/library/system.data.entity.dbcontext(v=vs.103).aspx

DbContext is usually used with a derived type that contains
DbSet properties for the root entities of the model. These
sets are automatically initialized when the instance of the derived
class is created.

My goal is to use the EF to access a DB through a WCF data service from a Silverlight client, where the some of the columns are unknown at runtime. Any better ideas would be appreciated

Answer 1

Neither WCF or EF is suitable technology for this situation. WCF and its autogenerated proxies expects compile time defined model – you can avoid this but as a result you will not work with strongly typed data contracts but with “generic data” and you will work with them on XML or JSON level.

In case of EF it is even worse there is no easy workaround to get dynamic behavior. You can change DB or even mapping (but not with code first – only with EDMX) in dynamic way but still at the end you need compiled classes representing your mapped data.

The part of documentation you are referencing is not about dynamic creation of mapping but only about dynamic initialization of mapping defined in design time.