Question

When is it required to use new in the select clause as in the following example? Thanks.

var results = from person in people
              select new { FN = person.FirstName, LN = person.LastName };

I’ve searched and partially understand this: “In the select new, we’re creating a new anonymous type with only the properties you need.” But does it mean I can omit new and not get an anonymous type?

To restate my question in another way: is ‘new’ optional? Is ‘new’ here similar to C# new where it is not required with value type?

Can I do this?

var results = from person in people
              select { FN = person.FirstName, LN = person.LastName };

Answer 1

No, new is not optional if you’re selecting “new” objects. (which is what you are doing. You are creating new objects of an anonymous type with 2 properties FN and LN)

Simply omitting new is a syntax error.

If you have an existing type you would like to use, (say you’ve defined a class Person with 2 properties FN and LN) then you can use that type. E.g.

var results = from person in people
              select new Person { FN = person.FirstName, LN = person.LastName };

(assuming Person has a parameterless constructor and FN and LN are properties with setters)

The only time you can omit new is if you are not creating a new object, for instance:

var results = from person in people
              select LN = person.LastName;

There you are selecting just the LastName and the result is an IEnumerable<string>