Hi

.. was it turns out about to write the same attribute the class answer as lasttime (its still true)

I am not sure if you can use it direct, but Umbraco has a [JsonCamelCaseFormatter] attribute which you can place on the methods/class

e.g

[JsonCamelCaseFormatter]  
public IActionResult MyMethodThatReturnsSomething() 

if for some reason you need to do that yourself (the Umbraco one does do something Angulary with its own version - not sure if that will effect things)

public class MyCamelCaseJsonFormatterAttribute : TypeFilterAttribute
{
    public MyCamelCaseJsonFormatterAttribute () : 
              base(typeof(MyCamelCaseJsonFormatterFilter))
    {
        Order = 2;
    }
}

public class MyCamelCaseJsonFormatterFilter : IResultFilter
{
    private readonly ArrayPool<char> _arrayPool;
    private readonly IOptions<MvcOptions> _options;

    public MyCamelCaseJsonFormatterFilter (ArrayPool<char> arrayPool, IOptions<MvcOptions> options)
    {
        _arrayPool = arrayPool;
        _options = options;
    }

    public void OnResultExecuted(ResultExecutedContext context)
    { }

    public void OnResultExecuting(ResultExecutingContext context)
    {
        if (context.Result is ObjectResult objectResult)
        {
            var serializerSettings = new JsonSerializerSettings()
            {
                ContractResolver = new CamelCasePropertyNamesContractResolver()
            };


            objectResult.Formatters.Clear();
            objectResult.Formatters.Add(new NewtonsoftJsonOutputFormatter(serializerSettings, _arrayPool, _options.Value));
        }
    }
}