C#•2y ago

✅ How do I add a JsonConverter subclass to a .NET 7 WebApplication?

I've written a couple of custom JsonConverter classes, and I've been able to get them in place for manual Json serialization/deserialization. However, I haven't managed to get them to be applied when using a Web Application and a class with the [ApiController] attribute. I'm currently setting it up like this:

WebApplicationBuilder builder = WebApplication.CreateBuilder();

builder.Services.Configure<JsonOptions>(options =>
{
    RegisterCustomConverters(options.SerializerOptions);
    options.SerializerOptions.PropertyNameCaseInsensitive = true;
});
builder.Services.AddControllers();
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

builder.Logging.ClearProviders();
builder.Logging.AddConsole();

WebApplication app = builder.Build();

WebApplicationBuilder builder = WebApplication.CreateBuilder();

builder.Services.Configure<JsonOptions>(options =>
{
    RegisterCustomConverters(options.SerializerOptions);
    options.SerializerOptions.PropertyNameCaseInsensitive = true;
});
builder.Services.AddControllers();
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

builder.Logging.ClearProviders();
builder.Logging.AddConsole();

WebApplication app = builder.Build();

where RegisterCustomConverters() is:

public static void RegisterConverters(JsonSerializerOptions serializerOptions)
{
    serializerOptions.Converters.Add(new CustomConverter1());
    serializerOptions.Converters.Add(new CustomConverter2());
}

public static void RegisterConverters(JsonSerializerOptions serializerOptions)
{
    serializerOptions.Converters.Add(new CustomConverter1());
    serializerOptions.Converters.Add(new CustomConverter2());
}

However, RegisterConverters() is never called, and when I sent a post request, it isn't deserialized using the custom converter. Any idea what I'm doing wrong here? Thanks

1 Reply

HughOP•2y ago

Ah, I appear to have fixed it by changing it to:

builder.Services.AddControllers()
    .AddJsonOptions(options =>
    {
        SWJsonConverters.RegisterConverters(options.JsonSerializerOptions);
        options.JsonSerializerOptions.PropertyNameCaseInsensitive = true;
    });

builder.Services.AddControllers()
    .AddJsonOptions(options =>
    {
        SWJsonConverters.RegisterConverters(options.JsonSerializerOptions);
        options.JsonSerializerOptions.PropertyNameCaseInsensitive = true;
    });

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✅ How do I add a JsonConverter subclass to a .NET 7 WebApplication?