ASP.NET Core API JSON serializersettings per request

Question

Based on some value in the request (header or in the url) I want to change the serialization of my DTO objects. Why? Well I\'ve applied the [JsonProperty(\"A\")]

Answer 1

Here are two options:

1. Manual formatting

Options you set by services.AddMvc().AddJsonOptions() are registered in DI and you can inject it into your controllers and services:

public HomeController(IOptions optionsAccessor)
{
    JsonSerializerSettings jsonSettings = optionsAccessor.Value.SerializerSettings;
}

To per-request override these serialization settings, you could use Json method or create JsonResult instance:

public IActionResult Get()
{
    return Json(data, new JsonSerializerSettings());

    return new JsonResult(data, new JsonSerializerSettings());
}

2. Result filter to replace JSON output

public class ModifyResultFilter : IAsyncResultFilter
{
    public ModifyResultFilter(IOptions optionsAccessor)
    {
        _globalSettings = optionsAccessor.Value.SerializerSettings;
    }

    public async Task OnResultExecutionAsync(
        ResultExecutingContext context,
        ResultExecutionDelegate next)
    {
        var originResult = context.Result as JsonResult;

        context.Result = new JsonResult(originResult.Value, customSettings);

        await next();
    }
}

Use it on action/controller:

[ServiceFilter(typeof(ModifyResultFilter ))]
public IActionResult Index() {}

Or create a custom attribute as described in documentation:

[ModifyResultAttribute]
public IActionResult Index() {}

Don't forget to register the filter in DI.