Configure input/output formatters on controllers with ASP.NET Core 2.1

Question

I am in the process of rewriting an old ASP.NET WebAPI 2.1 project to ASP.NET Core MVC 2.1. One of the problem I am facing is about porting the old behavior of the service w

Answer 1

Actually I found a way. I created an attribute which also implements IResultFilter and here is the OnResultExecuting method, where the magic happens:

public void OnResultExecuting(ResultExecutingContext context)
{
  var objectResult = context.Result as ObjectResult;
  if (objectResult != null)
  {
    var serializerSettings = new JsonSerializerSettings
    {
        ContractResolver = new DefaultContractResolver()
    };

    var jsonFormatter = new JsonOutputFormatter(
        serializerSettings,
        ArrayPool.Shared);

    objectResult.Formatters.Add(jsonFormatter);
  }
}

Basically here I am injecting a custom JSON formatter in every object result, before it is sent to the client. It appears (but I did not find any documentation about this) that in this way ASP.NET Core MVC prefers the injected formatter over the globally defined one.

I hopes it helps other because I was struggling on this...