using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        IEnumerable<Thing> list = null;

        var sut = list.AsQueryResult();

        Console.WriteLine(sut.Result.Count());

        Console.WriteLine(sut.TotalCount);

        list = new List<Thing> { new Thing { Data = "Works" } };

        sut = list.AsQueryResult();

        Console.WriteLine(sut.Result.Count());

        Console.WriteLine(sut.TotalCount);

    }

}

​

public class Thing

{

    public string Data  {get;set;}

}

​

public class QueryResult<T>

{

    public QueryResult(IEnumerable<T> result, int totalCount)

    {

        Result = result;

        TotalCount = totalCount;

    }

​

    public IEnumerable<T> Result { get; }

​

    public int TotalCount { get; }

}

​

public static class EnumerableExtension

{

    public static QueryResult<T> AsQueryResult<T>(this IEnumerable<T> result, int? totalCount = default)

    {

        return result == null ? new QueryResult<T>(Enumerable.Empty<T>(), totalCount ?? 0) : new QueryResult<T>(result, totalCount ?? result.Count());

    }

}