LinqPad and Entity Framework

Posted 31 May 2011, 16:36 | by | Perma-link

I'm a massive fan of LINQPad - it's much more lightweight than SQL Management Studio if you want to muck around with your data, and allows me to work against SQL with C#, rather than having to remember how to use cursors and the like when I've got some otherwise tedious data re-mapping to do.

That said, I'd never really pointed it at an Entity Framework EDM before, but I'd been wondering about the best way to tidy up the code for the tag clouds in the albums section of this site, so thought that I should see what I could do with the entity model as it stood, without resorting to stored procs.

Firing up the "Add Connection" wizard, I selected "Entity Framework" from the "Use typed data context from your own assembly", selected the website library, selected the (only) EDM from the library, and confirmed the provider.

LINQPad then created the data context correctly, so I pulled up a query to start working against it, only to get the following error message:

An assembly with the same identity 'System.Data.Entity, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' has already been imported. Try removing one of the duplicate references.

This was slightly confusing - obviously both my project and LINQPad are referencing the System.Data.Entity namespace, and if I remove the reference from my project, I won't be able to build it. How do I remove it from LINQPad then?

It turns out that I don't have to do either. The clue (for me) lay in the notes section of the "Using LINQPad with Entity Framework" page:

If your assembly references other assemblies, LINQPad will pick up these, too, providing they live in the same folder.

Note the bit in bold from the original page - it would appear that my reference to the System.Data.Entity library was set to "Copy Local". Setting that to false and restarting LINQPad removed the error message, allowing me to clean up the tag code somewhat.

Filed under: Entity Framework, Fixes, LINQ, Tools