Get ASP.NET Core 8 MVC controller to return JSON properties unchanged without lowercasing property names

Question

I have an ASP.NET Core 8 controller.

When I return an object serialized using Newtonsoft.Json in the Ok return below, it changes the properties to lower case in the JSON.

I want them to stay as declared in C# without having to put JsonPropertyName attribute on all the properties.

Instead of this:

{ 
   "id":"0",
   "name": "Foo"
}

I want to get this representation instead:

{ "Id: "0", "Name": "Foo" }

This is the C# class for this:

class Foo
{
    public string Id { get; set; }
    public string Name { get; set; }
}

/// </summary>
[ApiController]
public class ManagerApiController : ControllerBase
{
    [Route("/api/v1/search-approval-workflows")]
    [ValidateModelState]
    [SwaggerOperation("SearchApprovalWorkflowsGet")]
    public virtual IActionResult SearchApprovalWorkflowsGet([FromQuery] string s)
    {
         // ...
         return OK(foo);
    }
}

I tried

DefaultContractResolver resolver = 
   new DefaultContractResolver
       {
           NamingStrategy = new DefaultNamingStrategy()
       };

resolver.NamingStrategy.OverrideSpecifiedNames = false;

string json = JsonConvert.SerializeObject(obj, new JsonSerializerSettings
                                               {
                                                   ContractResolver = resolver,
                                                   Formatting = Formatting.Indented
                                               });
return json;

But that didn't work.

I also tried returning new JsonResult(foo), but again without luck.

Answer 1

Thanks PowerMouse.

This was it. Example shows for json.net and newtonsoft, maybe only one needed depending on what is used.

services
      .AddMvc().AddJsonOptions( jsonOpt =>
      {
          jsonOpt.JsonSerializerOptions.PropertyNamingPolicy = null;
      })
      .AddNewtonsoftJson(opts =>
      {
          opts.SerializerSettings.ContractResolver = null;
       
      })