JsonInputFormatter fails to use custom SerializerSettings

[kwaclaw]

Using MVC as of today, March 10, 2016.
Modifiying SerializerSettings like so:

public void ConfigureServices(IServiceCollection services)
{
    var mvc = services.AddMvc(config => {
        ConfigureJson(config);
    });
    ...
}

void ConfigureJson(MvcOptions config) {
    var jsonSettings = new JsonSerializerSettings();
    ...
    jsonSettings.Binder = new Json.KnownTypesSerializationBinder(KnownTypes.Map);
    jsonSettings.TypeNameHandling = TypeNameHandling.All;

    var jsonInputFormatters = config.InputFormatters.OfType<JsonInputFormatter>();
    foreach (var jif in jsonInputFormatters)
        jif.SerializerSettings = jsonSettings;

}

The custom binder is never called. It looks like the new SerializerSettings are ignored altogether.
Looking at the JsonInputFormatter code:

protected virtual JsonSerializer CreateJsonSerializer()
{
    if (_jsonSerializerPool == null)
    {
        _jsonSerializerPool = _objectPoolProvider.Create<JsonSerializer>();
    }

    return _jsonSerializerPool.Get();
}

I don't see how the SerializerSettings get applied.
This is in contrast to the JsonOutputFormatter:

    protected virtual JsonSerializer CreateJsonSerializer()
    {
        if (_serializer == null)
        {
            _serializer = JsonSerializer.Create(SerializerSettings);
        }

        return _serializer;
    }

[kwaclaw]

I resolved this temporarily by creating a "fixed" JsonInputFormatter that overrides CreateJsonSerializer.

[kwaclaw]

Just curious: Is there a reason why the JsonOutputFormatter does not use an object pool for the Json serializer?

[rynowak]

The objectpool isn't needed for output because we can use a single shared instance.

For input we need to attach to the "errors" callback so each JsonSerializer is stateful while it's being used