Make a new generic list from a list within a list in Linq with lambda expressions?

Question

Okay so I have a POCO class that may contain another POCO class as an array. In some instances when I get the data I want to CREATE a list of the lists but not as a level down but all on the same level. I think I am missing something very simple so I thought I would ask here. I keep trying different syntax for Lambdas but the data is there, I can just never make it appear near the top. I would like the solution to be in lambdas if possible instead of doing the old school foreach. I was not sure if you can do this inline at all or if you have to declare a collection first and then add to it. Where I am at:

class Program
    {
        public class lowerlevel
        {
            public string ChildName;
        }

        public class upperlevel
        {
            public string ItemName;

            public lowerlevel[] ChildNames;
        }

        static void Main(string[] args)
        {
            // Create a list of a POCO object that has lists in it as well.
            List<upperlevel> items = new List<upperlevel>
                {
                    // declaration of top level item
                    new upperlevel
                    {
                        ItemName = "FirstItem",
                        // declaration of children
                        ChildNames = new lowerlevel[] 
                            {new lowerlevel {ChildName = "Part1"}, new lowerlevel {ChildName = "Part2"}},

                    },
                    // declaration of top level item
                    new upperlevel
                    {
                        ItemName = "SecondItem",
                        // declaration of children
                        ChildNames = new lowerlevel[] { new lowerlevel { ChildName = "Part3" } }
                    }
                };


            var stuff = items.Select(l1 => l1.ChildNames.ToList().Select(l2 => 
                new lowerlevel
                {
                    ChildName = l2.ChildName
                }))
                .ToList();

            // Arghh!  I just want to make a new list with lambdas that is NOT nested a level down!  This is NOT what I want but it is valid.
            stuff.ForEach(n => n.ToList().ForEach(n2 => n2.ChildName));

            // I want this but it does not work as I am not doing the expression right 
            // stuff.Foreach(n => n.ChildName);

        }

    }

That appears to be it if I place it right after 'items' in my example. Thanks! — djangojazz
– djangojazz, Commented May 10, 2013 at 19:30

Maess · Accepted Answer · 2013-05-13 13:21:28Z

1

Try using a SelectMany() Rather than .Select()

var stuff = items.SelectMany...

answered May 13, 2013 at 13:21

Maess

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