CODEWITHSUNDEEP
c#
gakera
gakera

Reputation: 3677

How to convert Array of objects into an IEnumerable of inheriting object?

I have PInfo2[] pInfo and need to use it as an IEnumerable<PInfo3> betterInfo where public class PInfo3 : PInfo2

What I've tried, but doesn't work: 

(IEnumerable<PInfo3>)pInfo //Runtime error: "Unable to cast object of type 'PInfo2[]' to type 'System.Collections.Generic.IEnumerable`1[

IEnumerable<PInfo3> betterInfo = pInfo as IEnumerable<PInfo3>; //Always null after cast.

What am I doing wrong, aka how am I being dumb? Do I need to for-loop through the array? I don't know why but I was hoping I didn't have to do that.

Upvotes: 0

Views: 299

Answers (1)

krillgar
krillgar

Reputation: 12805

You can use LINQ to cast the objects of the enumeration to a different related type.

pInfo.Cast<PInfo3>();

Now, this can cause some issues if there are some elements in the collection that can't be cast, but there are ways around that as well (see Edit):

pInfo.Select(p => (PInfo3)p).Where(p => p != null);

The Cast should be used when you know that the conversion will succeed, and the second when there could be elements that can't make the conversion.

EDIT

Per Daniel A. White's comment below, there is also the .OfType<T>() method, which will only get the items that match the requested type, and avoid the IllegalCastException that Cast<T>() will throw.

For additional details, see this answer.

Upvotes: 1

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