Entity Framework 4: How to code projection to a class type?

Question

If I have a class like the following:

public class Customer {
    public int    id    {get;set;}
    public string name  {get;set;}
    public string line1 {get;set;}
    public string line2 {get;set;}
    public string line3 {get;set;}
    public string line4 {get;set;}
}

And I only want to select the ID and Name values, leaving the rest null.

var myCustomerList = DC.Customer.Select( 
                     p => new Customer { id = p.id, name = p.name });

I get the following error:

The entity or complex type 'MyModel.Customer' cannot
be constructed in a LINQ to Entities query.

How else would you do it? Am I required to specify all the Class's fields?

Answer 1

Try this:

var myCustomerList = from c in DC.Customer 
                     select new { id = p.id, name = p.name };

The above will create an Anonymous Type.

Practical Application:

"var myCustomerList" <-- Anonymous Type.

An anonymous type with two properties "id" and "name". Also, "var" lets you create an Implicitly typed local variable. This means:

a) You didn't have to declare/write a class structure to hold a type with only those two properties;

b) You don't have to maintain that either - you can change the structure of the above query, and "it just works".