JsonSerializer Struct with asp-net core 3.0

Question

I'm having issues with .net core 3.0 when I convert a struct to a json. (with wasn't a problem when I was using .net core 2.2)

This is my struct

[Serializable]
struct Item
{
   public int A;
   public string B;
   public int C;
   public decimal D;
   public decimal E;
}

This is my code

var linhas = COD_PRODUTO.Count;
Item[] item = new Item[linhas];

for (int cont = 0; cont < linhas; cont++)
{
   DESCRICAO = _context.Produtos.Where(c => c.COD_PRODUTO == COD_PRODUTO[cont]).Select(c => 
   c.DESCRICAO).Single().ToString();

   item[cont].A = COD_PRODUTO[cont];
   item[cont].B = DESCRICAO;
   item[cont].C = QUANTIDADE[cont];
   item[cont].D = PRECOUNITARIO[cont];
   item[cont].E = TOTAL[cont];
}

var json = JsonSerializer.Serialize(item); //3.0
Debug.WriteLine("----------------------" + json);

return new JsonResult(json);

It's returning me empty values, any help?

Answer 1

As of 3.0, ASP.NET Core uses the System.Text.Json to serialize/deserialize json. And the public properties are serialized by default. See official docs:

Serialization behavior

By default, all public properties are serialized.

1. To fix that issue, you could change those public fields to public properties as below:

   [Serializable]
   struct Item
   {
       public int A {get;set;}
       public string B {get;set;}
       public int C {get;set;}
       public decimal D {get;set;}
       public decimal E {get;set;}
   }
   

2. Or as an alternative, you can follow the official docs to fallback to the old behavior by using the Newtonsoft.Json package:

   services.AddControllers()
       .AddNewtonsoftJson(opts =>{ /*...*/ });