LINQ - Add property to results

Question

Is there a way to add a property to the objects of a Linq query result other than the following?

var query = from x in db.Courses
                select new
                {
                    x.OldProperty1,
                    x.OldProperty2,
                    x.OldProperty3,
                    NewProperty = true
                };

I want to do this without listing out all of the current properties of my object. There are many properties, and I don't want to have to update this code whenever I may change my class.

I am still learning with LINQ and I appreciate your suggestions.

Answer 1

I suppose you could return a new object composed of the new property and the selected object, like:

var query = from x in db.Courses
                select new
                {
                    Course x,
                    NewProperty = true
                };

Answer 2

eking's answer will be the most straightforward approach.

If that doesn't work for you (because you need to pass the results around or whatever), and assuming the class you're dealing with already defines the property you want to set, you could create a copy constructor or factory method that takes an existing instance plus the value of the property you want to set:

var query = from x in db.Courses
            select new Course(x, valueOfNewProperty);

Alternatively, if Course doesn't define the property, you could subclass it and use the same approach:

var query = from x in db.Courses
            select new CourseWithExtraProperty(x, valueOfNewProperty);

(obviously, pick a better name for your subclass)

Again, though, unless you really need to do this, stick with eking's solution.

Answer 3

Add it with partial classes:

public partial class Courses
{
    public String NewProperty { get; set; }
}

Then you can assign it after you've created the object.