Entity Framework: Ignore Columns

Question

Can you do this with the Entity Framework? Yes; it's easy. Can you do this with the Entity Framework designer? Unfortunately, that is much harder.

The problem you're having is that the column exists in the storage schema (SSDL) in your EDMX. Removing the column with the GUI designer simply removes it from the client schema, not the mapping or the storage schema. However, it's simple enough to go into the EDMX and remove it. Having done that, you can also remove it from the mapping in the client schema portions of the EDMX, and the entity framework will longer complain that it is unmapped.

Problem solved, right?

Well, no. When you use the GUI designer to update the EDMX from the database, the storage schema is thrown away and re-generated. So your column will come back. As far as I know, there is no way to tell the GUI designer to never map a particular column. So you will have to re-do this every time you update with the GUI designer. Fortunately, the EDMX is XML, so you can do this with a XML transform, LINQ, or the XML tool of your choice.

Can you not create a view with the columns you need and import it through entity function wizard and map it to your entities?

You could modify the text template to ignore these columns when generating your entity classes. For example if you added "IGNORE" to the documentation summary, you could modify the template to ignore them by replacing;

Dim simpleProperties as IEnumerable(Of EdmProperty) = typeMapper.GetSimpleProperties(entity)

with;

Dim simpleProperties as IEnumerable(Of EdmProperty) = typeMapper.GetSimpleProperties(entity).Where(Function(p) p.Documentation is nothing orelse p.Documentation.Summary.IndexOf("IGNORE")<0)