'System.Array' does not contain a definition for 'Take'

[katoa]

 Here is a very simplified version of a transform I'm trying to create:

TransformResults = users =>
    from user in users
    let subpartcount = { calculation }
    select new
    {
        user.Id,
        SubParts = user.Parts.Split(' ').Take(subpartcount)
        //SubParts = Enumerable.Take(user.Parts.Split(' '), subpartcount)
        //SubParts = Enumerable.Take((IEnumerable<string>)user.Parts.Split(' '), subpartcount)
    };


My first attempt is the code not commented out.   After searching through the forum, I see that the server can't deal with LINQ extension methods, so I tried the other commented out attempts, but with the same exception.

Perhaps this is because Take itself is implemented using an internal extension method?

In any case, how can I do this?

[Chris Marisic]

You're not enumerating the Take() result leaving it as a deferred enumerable. This is probably causing problems. 

[katoa]

True, but adding a ToArray() after the Take to force enumeration (whether extension method or direct call) still results in the same exception.

[Oren Eini (Ayende Rahien)]

The actual issue is that the Split() method returns an System.Array, while for most things in RavenDB we rely on an internal class that knows how to map common extension methods.

Your usage of the Enumerable.Take() method is good, but the problem is that you are doing that as a C# code, and as far as the compiler is concerned, both options are identical.

This might work:

        SubParts = ((string[])user.Parts.Split(' ')).Take(subpartcount)

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[Chris Marisic]

Are you sure about that?

From resharper decompile:

    [ComVisible(false)]

    [__DynamicallyInvokable]

    public string[] Split(string[] separator, StringSplitOptions options)

https://msdn.microsoft.com/en-us/library/b873y76a(v=vs.110).aspx

public string[] Split(

[Oren Eini (Ayende Rahien)]

Yes, I am.

It isn't anything to do with _invoking_ Split(), it is about being able to bind an extension method to it in dynamic context.

That isn't allowed, which is something that you generally don't notice in ravendb because we work very hard to make sure that this is the case

[Chris Marisic]

got it, dynamic context makes it odd.

[katoa]

Yep, that did the trick.   And I understand the difficulties involved.

Thanks!