Best way to convert IList or IEnumerable to Array

Question

I have a HQL query that can generate either an IList of results, or an IEnumerable of results.

However, I want it to return an array of the Entity that I'm selecting, what would be the best way of accomplishing that? I can either enumerate through it and build the array, or use CopyTo() a defined array.

Is there any better way? I went with the CopyTo-approach.

Answer 1

Which version of .NET are you using? If it's .NET 3.5, I'd just call ToArray() and be done with it.

If you only have a non-generic IEnumerable, do something like this:

IEnumerable query = ...; MyEntityType[] array = query.Cast<MyEntityType>().ToArray(); 

If you don't know the type within that method but the method's callers do know it, make the method generic and try this:

public static void T[] PerformQuery<T>() {     IEnumerable query = ...;     T[] array = query.Cast<T>().ToArray();     return array; } 

Answer 2

Put the following in your .cs file:

using System.Linq; 

You will then be able to use the following extension method from System.Linq.Enumerable:

public static TSource[] ToArray<TSource>(this System.Collections.Generic.IEnumerable<TSource> source) 

I.e.

IEnumerable<object> query = ...; object[] bob = query.ToArray();