Question

I have a View which looks similar to this:

SELECT Id, Name
FROM Users
UNION ALL
SELECT NULL as [Id], NULL as [Name]

When I try to map to this view in Entity Framework, it just fails. I don’t get an error, but the view does not exist in my data store. Why is this? Is there a way around it?

Answer 1

It is because Visual Studio cannot infers the Primary Key of your View.
You can see the error message within edmx file by open it with XML editor and see the SSDL section.
Here is error message that results from my Model(which I created some View like yours within my Database just to emulate) :

Errors Found During Generation:
warning 6013: The table/view 'PhoneBook.dbo.ContactCustomer' does not have 
a primary key defined and no valid primary key could be inferred.
This table/view has been excluded. To use the entity, 
you will need to review your schema, 
add the correct keys, and uncomment it.

It is not true that Union is not supported in EF 4.
But I think the problem is that Visual Studio saw your view as the odd View.

You can doing some experiment by create another View and compares them (using update model from database menu within model designer).

And you can modify the Model by hand (manual typing the edmx file) to define the Primary Key to resolve this.