Client-Side Blazor OrderByDescending

[mkArtakMSFT]

From @matheusjulio96 on Wednesday, June 19, 2019 2:02:04 PM

The bug: Execute an OrderByDescending query throw the error 'Unhandled exception rendering component: System.NullReferenceException: Object reference not set to an instance of an object.'

Steps to reproduce the behavior:

1. Using this version of ASP.NET Core 3.0.0-preview6.19307.2 with Client-Side project
2. Run this code:

@code{
    class Pet
    {
        public string Name { get; set; }
        public int Age { get; set; }
    }

    protected override void OnInit()
    {
        Pet[] pets = { new Pet { Name="Barley", Age=8 },
                       new Pet { Name="Boots", Age=4 },
                       new Pet { Name="Whiskers", Age=1 } };

        var query = pets.AsQueryable().OrderByDescending(pet => pet.Age);

        foreach (Pet pet in query)
            Console.WriteLine("{0} - {1}", pet.Name, pet.Age);
    }
}

3. See error Screenshot
   

Expected behavior: Execute the query and print the values.

Ps: OrderBy query works fine.

Copied from original issue: dotnet/aspnetcore#11371

[matheusjulio96]

Seems related with #8872

[lewing]

using System;
using System.Runtime.InteropServices;
using System.Linq;

public class TestQueryableOrderBy
{
    public static void Main (String[] args) {
        OnInit();
        Console.WriteLine ("Hello, World!");
    }

    class Pet
    {
        public string Name { get; set; }
        public int Age { get; set; }
    }

    static void OnInit()
    {
        Pet[] pets = { new Pet { Name="Barley", Age=8 },
                       new Pet { Name="Boots", Age=4 },
                       new Pet { Name="Whiskers", Age=1 } };

        var query = pets.AsQueryable().OrderByDescending(pet => pet.Age);

        foreach (Pet pet in query)
            Console.WriteLine("{0} - {1}", pet.Name, pet.Age);
    }
}

Exception:System.NullReferenceException: Object reference not set to an instance of an object.
  at System.Linq.EnumerableRewriter.FindEnumerableMethod (System.String name, System.Collections.ObjectModel.ReadOnlyCollection`1[T] args, System.Type[] typeArgs) <0x1874028 + 0x000ac> in <7003b7b7722e4d88a36c3d5cbc5c762d>:0 
  at System.Linq.EnumerableRewriter.VisitMethodCall (System.Linq.Expressions.MethodCallExpression m) <0x186d900 + 0x0013c> in <7003b7b7722e4d88a36c3d5cbc5c762d>:0 
  at System.Linq.Expressions.MethodCallExpression.Accept (System.Linq.Expressions.ExpressionVisitor visitor) <0x1866428 + 0x0000c> in <7003b7b7722e4d88a36c3d5cbc5c762d>:0 
  at System.Linq.Expressions.ExpressionVisitor.Visit (System.Linq.Expressions.Expression node) <0x18662f0 + 0x00018> in <7003b7b7722e4d88a36c3d5cbc5c762d>:0 
  at System.Linq.EnumerableQuery`1[T].GetEnumerator () <0x18660e8 + 0x00022> in <7003b7b7722e4d88a36c3d5cbc5c762d>:0 
  at System.Linq.EnumerableQuery`1[T].System.Collections.Generic.IEnumerable<T>.GetEnumerator () <0x1865b10 + 0x00004> in <7003b7b7722e4d88a36c3d5cbc5c762d>:0 
  at TestQueryableOrderBy.OnInit () <0x17d71e0 + 0x00134> in <5bdd73753a1f47d98849c347b9dc492f>:0 
  at TestQueryableOrderBy.Main (System.String[] args) <0x716820 + 0x00000> in <5bdd73753a1f47d98849c347b9dc492f>:0

I'm seeing the same failure with OrderBy though.