Change System.Text.Json Serialization Options of a single ASP.NET Core API controller or single Action in ASP.NET Core 3

Question

I'm having two controller controllers: ControllerA and ControllerB. The base class of each controller is ControllerBase.

The ControllerA needs to deserialize JSON in the default option

JsonSerializerOptions.IgnoreNullValues = false;

The ControllerB needs to deserialize JSON with option

JsonSerializerOptions.IgnoreNullValues = true;

I know how to set this option global in Startup.cs

services.AddControllers().AddJsonOptions( options => options.JsonSerializerOptions.IgnoreNullValues = true);

But how to set specific deserialize options to Controller or Action? (ASP.NET Core 3 API)

You can try to achieve it with an ActionFilter, and [this SO thread](https://stackoverflow.com/questions/52605946/change-the-json-serialization-settings-of-a-single-asp-net-core-controller) discussed a similar requirement, you can refer to it. — Fei Han, Feb 04 '20 at 07:52
Does this answer your question? [Change the JSON serialization settings of a single ASP.NET Core controller](https://stackoverflow.com/questions/52605946/change-the-json-serialization-settings-of-a-single-asp-net-core-controller) — Ian Kemp, Oct 05 '20 at 14:25

McX · Answer 1 · 2020-11-10T13:08:55.050

1

As suggested by Fei Han, the straight-forward answer is to use on ControllerB the attribute NullValuesJsonOutput :

public class NullValuesJsonOutputAttribute : ActionFilterAttribute
{
    private static readonly SystemTextJsonOutputFormatter Formatter = new SystemTextJsonOutputFormatter(new JsonSerializerOptions
    {
        IgnoreNullValues = true
    });

    public override void OnActionExecuted(ActionExecutedContext context)
    {
        if (context.Result is ObjectResult objectResult)
            objectResult.Formatters.Add(Formatter);
    }
}

edited Nov 10 '20 at 13:08

answered Oct 05 '20 at 14:22

McX

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You might want to post this answer on the question I've linked as a duplicate, as this question is likely to get closed. – Ian Kemp Oct 05 '20 at 14:27
@IanKemp There's already a good answer on the duplicate (also pointed by Fei Han), which I adapted for this question. – McX Oct 07 '20 at 07:34

Change System.Text.Json Serialization Options of a single ASP.NET Core API controller or single Action in ASP.NET Core 3

1 Answers1