How can I extract a list of Tuple from a specific table with Entity Framework / LINQ?

Question

I need to extract a list of couple \'ID\'/\'Name\' from a large table in C# .NET with Entity Framework.

I try this request :

List

        

Answer 1

You can do it with a middle-step by selecting an anonymous type:

db.Resource.Select(x => new { x.Resource_ID, x.Name }).AsEnumerable().Select(x => Tuple.Create(x.Resource_ID, x.Name)).ToList();

Creating a tuple is not a supported operation in Linq To Entities, so you have to select an anonymous type, which would be an equivalent to:

SELECT [Resource].[Resource_ID], [Resource].[Name]

then move to LINQ to Objects by AsEnumerable and get your tuple.

Answer 2

You can create a list from db.Resource and use LINQ to Collections to erase this limitation:

var list = db.Resource.ToList().Select(res => Tuple.Create(res.Resource_ID, res.Name));

The Tuple class does have some constructors (up to 8 items), but the Create() helper method makes the creation more straightforward.