"Target object is not an ExpandoObject" exception being thrown when using GroupBy

[FernandoGPinto]

Hi

I am using dynamic GroupBy on a union of records and getting a Target object is not an ExpandoObject exception thrown by DynamicIndex when trying to run the query and obtain a list of records using the following code:

var fireExits = _context.View_SupplyChainSurveyResults.Select("new ( FireExits As FireAndEmergency )").AsEnumerable();

var fireExtinguishers = _context.View_SupplyChainSurveyResults.Select("new ( FireExtinguishersWorkArea As FireAndEmergency )").AsEnumerable();

var unionAll = fireExits.Concat(fireExtinguishers).AsQueryable();

var recordList = unionAll.GroupBy("FireAndEmergency").Select("new (Key as Label, Count() as Count)").ToDynamicList();

DynamicIndex only seems to be called by the GroupBy operator. Is there a limitation to this operator that I am anware of or am I missing a conversion?

Exception:

Exception thrown: 'System.InvalidOperationException' in System.Linq.Dynamic.Core.dll
An exception of type 'System.InvalidOperationException' occurred in System.Linq.Dynamic.Core.dll but was not handled in user code
Target object is not an ExpandoObject
  at System.Linq.Dynamic.Core.Dynamic.DynamicIndex(Object obj, String name)   
  at System.Linq.Lookup`2.Create[TSource](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
  at System.Linq.GroupedEnumerable`3.GetEnumerator()
  at System.Linq.EnumerableQuery`1.GetEnumerator()
  at System.Linq.EnumerableQuery`1.System.Collections.Generic.IEnumerable<T>.GetEnumerator()
  at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
  at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
  at SupplyChainWebApp.Data.SurveyDataAccessLayer.GetResponseAnalysisGroupedChartsData[T](Int32 month, String contract, String chartType)

[JonathanMagnan]

Hello @FernandoGPinto ,

Do you think you could provide a runnable project sample for this issue? It will help my developer to get started to investigate it faster and make sure nothing is missing.

Providing a project sample is now REQUIRED. It happened too many times that something was missing to investigate and/or answer an issue.

Try to create a new project with only the minimal code (having too many non-related codes doesn’t help either).

You can send it to [email protected] if you need to keep the source private

Best Regards,

Jon

---

Performance Libraries
context.BulkInsert(list, options => options.BatchSize = 1000);
Entity Framework Extensions • Entity Framework Classic • Bulk Operations • Dapper Plus

Runtime Evaluation
Eval.Execute("x + y", new {x = 1, y = 2}); // return 3
C# Eval Function • SQL Eval Function

[FernandoGPinto]

Hi @JonathanMagnan,

Thanks for reponding so quickly. Below you can find a simplified runnable version of my code. The exception thrown is the same.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Dynamic.Core;
					
public class Program
{		
	public static void Main()
	{
		var list = GenerateDummyData();

		var fireExits = list.Select("new ( FireExits As FireAndEmergency )").AsEnumerable();

		var fireExtinguishers = list.Select("new ( FireExtinguishersWorkArea As FireAndEmergency )").AsEnumerable();

		var unionAll = fireExits.Concat(fireExtinguishers).AsQueryable();

		var recordList = unionAll.GroupBy("FireAndEmergency").Select("new (Key, Count() as Count)");

		foreach (var record in recordList)
		{
			string str = record.ToString();
			Console.WriteLine(str);
		}
	}
	
	public static IQueryable<View_SupplyChainSurveyResults> GenerateDummyData()
	{
		var list = new List<View_SupplyChainSurveyResults>();

		var ex1 = new View_SupplyChainSurveyResults();
		ex1.FireExits = false;
		ex1.FireExtinguishersWorkArea = true;

		var ex2 = new View_SupplyChainSurveyResults();
		ex2.FireExits = true;
		ex2.FireExtinguishersWorkArea = false;

		var ex3 = new View_SupplyChainSurveyResults();
		ex3.FireExits = true;
		ex3.FireExtinguishersWorkArea = false;

		list.Add(ex1);
		list.Add(ex2);
		list.Add(ex3);

		return list.AsQueryable();
	}
	
	public class View_SupplyChainSurveyResults
    {
        public bool FireExits { get; set; }
        public bool FireExtinguishersWorkArea { get; set; }
    }
}

[JonathanMagnan]

Thank you :) My developer will look at it

[JonathanMagnan]

Hello @FernandoGPinto ,

Unfortunately, I don't think it will be possible to support your case, I believe you reached the limitation of the library.

Anonymous type is created on the fly, even if they have similar different, they are different type so trying to make a union on both lists make it currently impossible to do such request.

I don't think anything will be done here due to the amount of time required to make it works.

[StefH]

Actually, the union/concat (var unionAll = fireExits.Concat(fireExtinguishers).AsQueryable();) does work, because there is a check in the code to reuse a dynamic generated type.
(https://github.com/zzzprojects/System.Linq.Dynamic.Core/blob/master/src/System.Linq.Dynamic.Core/DynamicClassFactory.cs#L117)

So because both anonymous classes have a property FireAndEmergency which is a bool, they are the same. So they can be used in the Union call.

(possible) solution

Hello @FernandoGPinto, a possible solution is to introduce a real class to capture the data.

See example c# code below:

class Program
{
    public static void Main()
    {
        var list = GenerateDummyData();

        var fireExits = list.Select<X>("new ( FireExits As FireAndEmergency )"); // Cast to X

        var fireExtinguishers = list.Select<X>("new ( FireExtinguishersWorkArea As FireAndEmergency )"); // Cast to X

        var unionAll = fireExits.Union(fireExtinguishers).AsQueryable();

        var recordList = unionAll.GroupBy("FireAndEmergency").Select("new (Key, Count() as Count)");

        foreach (var record in recordList)
        {
            string str = record.ToString();
            Console.WriteLine(str);
        }
    }

    public static IQueryable<View_SupplyChainSurveyResults> GenerateDummyData()
    {
        var list = new List<View_SupplyChainSurveyResults>();

        var ex1 = new View_SupplyChainSurveyResults();
        ex1.FireExits = false;
        ex1.FireExtinguishersWorkArea = true;

        var ex2 = new View_SupplyChainSurveyResults();
        ex2.FireExits = true;
        ex2.FireExtinguishersWorkArea = false;

        var ex3 = new View_SupplyChainSurveyResults();
        ex3.FireExits = true;
        ex3.FireExtinguishersWorkArea = false;

        list.Add(ex1);
        list.Add(ex2);
        list.Add(ex3);

        return list.AsQueryable();
    }

    public class X
    {
        public bool FireAndEmergency { get; set; }
    }

    public class View_SupplyChainSurveyResults
    {
        public bool FireExits { get; set; }
        public bool FireExtinguishersWorkArea { get; set; }
    }
}

[FernandoGPinto]

Hi @StefH @JonathanMagnan

Thank you for taking time to look into this and for proposing a solution. It works great and has solved the issue I was grappling with 👍