LINQ: How to get parent types' properties while getting their children collections

Question

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I have a collection of parent types that contains a list of children types:

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public class ParentType
{

    public int ID;
    public string Name;
    public List<ChildType> ChildTypes { get; set; }

}

public class ChildType
{

    public int ID;
    public string Name;

}

---

I need to use LINQ to turn them into a collection of the following type:

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public class MixedType
{

    public int ParentID;
    public string ParentName;
    public int ChildID;
    public string ChildName;

}

---

I've already tried (select many) but could not get the ParentType properties.

Answer 1

Provided I understand what you are going to do, you have to use this overload of SelectManay extension which allows you to invoke a result selector function on each element therein.

The query should be:

var lst = new List<ParentType>();

var query = lst.SelectMany(p => p.ChildTypes, 
                                (parent, child) => new { parent, child }
                          )
               .Select(p => new MixedType
                            {
                                ChildID = p.child.ID,
                                ChildName = p.child.Name,
                                ParentID = p.parent.ID,
                                ParentName = p.parent.Name
                            });

Good luck!