How do I merge non-generic IEnumerable in C#

Question

I'm trying to have one object inherit from another object where properties of type IEnumerable will be merged together.

Both objects are of same class.

foreach (var property in typeof(Placeholder).GetProperties())
{
    var childProperty = property.GetValue(childPlaceholder);
    var parentProperty = property.GetValue(parentPlaceholder);

    IEnumerable childIEnumerable = childProperty as IEnumerable;
    IEnumerable parentIEnumberable = parentProperty as IEnumerable;

    // How do I merge childIEnumerable with parentIEnumberable into one IEnumerable
}

Answer 1

There's the LINQ Cast<T> method that allows you to turn a non-generic Enumerable to a generic one. Assuming that you know the Parent and Child types (where Child: Parent ):

foreach (var property in typeof(Placeholder).GetProperties())
{
    var childProperty = property.GetValue(childPlaceholder);
    var parentProperty = property.GetValue(parentPlaceholder);
    IEnumerable childIEnumerable = childProperty as IEnumerable;
    IEnumerable parentIEnumerable = parentProperty as IEnumerable;
    IEnumerable<Parent> mergedEnumerable = childIEnumerable
        .Cast<Child>()
        .Concat(parentIEnumerable.Cast<Parent>());
}

If you don't know the specific types, you can also cast them to object :

IEnumerable<object> merged = childIEnumerable
    .Cast<object>()
    .Concat(parentIEnumerable.Cast<object>());