Object has the same property multiple times

Question

When I inspect my object in the debugger, it has 3 different entries for the property VgnItm.

How does an object get multiple of a property?

Here is the class with multiple of VgnItm property:

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using Nest;
using Newtonsoft.Json;

namespace Vepo.Domain
{
    [Serializable]
    public class VgnItmEstDto : CreatedBySomeoneDto
    {
        [Required]
        public int VgnItmId { get; set; }
        public int? EstId { get; set; }
        [Required]
        public int NotInEstCount { get; set; } = 0;
        [Required]
        public int InEstCount { get; set; } = 0;
        public double? Price { get; set; }
        [Object]
        public EstDto Est { get; set; }
        public VgnItmDto VgnItm { get; set; }
        public string Discriminator { get; set; }
    }

    public class VgnItmEstDto<TVgnItmDto> : VgnItmEstDto
        where TVgnItmDto : VgnItmDto
    {
        public new TVgnItmDto VgnItm { get; set; }
    }
}

A likely reason for the duplicate property names is that you redeclared the property in an inherited class, creating another property that has the same name. — Sweeper, Apr 28 '23 at 09:53
Don't you know the [new modifier](https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/new-modifier)? — shingo, Apr 28 '23 at 09:56
Does this answer your question? [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Palle Due, Apr 28 '23 at 10:06
@PalleDue No, this is a completely different question. That is just a plain old null reference exception question. — BeniaminoBaggins, Apr 28 '23 at 10:14
@MakePeaceGreatAgain So there is no place on the internet for a question about a C# object having the same property multiple times? — BeniaminoBaggins, Apr 28 '23 at 10:20

jmcilhinney · Accepted Answer · 2023-04-28T10:09:30.883

1

Hiding a property with the new keyword doesn't mean that that property ceases to exist. Of course there are two properties with the same name: the one you declared and the one you hid. If you want to hide the base property with one of a more specific type then you would usually implement the getter and setter to pass through to the base property:

public class VgnItmEstDto<TVgnItmDto> : VgnItmEstDto
    where TVgnItmDto : VgnItmDto
{
    public new TVgnItmDto VgnItm
    {
        get => base.VgnItm;
        set => base.VgnItm = value;
    }
}

edited Apr 28 '23 at 10:09

answered Apr 28 '23 at 10:05

jmcilhinney

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redirecting the new property to the hidden one won't change anything on serialization. The property will still occur twice. – MakePeaceGreatAgain Apr 28 '23 at 10:09
@MakePeaceGreatAgain, it was my impression that the `NullReferenceException` was because the base property was not being set when setting the new property. This will address that. – jmcilhinney Apr 28 '23 at 10:11

Object has the same property multiple times

1 Answers1