Question

How can we express the following code using query expression:

        var result = collection1
            .Select(p1 => p1. collection2
                .Select(p2 => p2.collection3
                                       .Select(...)));

Thank you

Answer 1

Well you can use:

var result = from p1 in collection1
             select p1.collection2 into p2
             select p2.collection3 into p3
             select p3....;

However, I suspect it’s more likely that your original Select calls were meant to be SelectMany, in which case you’d get:

var result = from p1 in collection1
             from p2 in p1.collection2
             from p3 in p2.collection3
             select p3....;

It really depends on what you’re trying to do.