ASP.NET Core–Serializing enums

By default when you return an enum value as part of your data contract in ASP.NET Core, it will be serialized as a number value.

Here is an example of our data contract:

	public class WeatherForecast
	{
	public DateTime Date { get; set; }
	public int TemperatureC { get; set; }
	public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
	public string? Summary { get; set; }
	public WeatherType WeatherType { get; set; }
	}

view raw WeatherForecast.cs hosted with ❤ by GitHub

	public enum WeatherType
	{
	Sunny=0,
	Rainy=1
	}

view raw WeatherType.cs hosted with ❤ by GitHub

And how it will be returned by our API:

	{
	"date": "2022-09-25T10:52:14.8018192+02:00",
	"temperatureC": -8,
	"temperatureF": 18,
	"summary": "Scorching",
	"weatherType": 1
	}

view raw Response.json hosted with ❤ by GitHub

But what if we want to return the enum value as a string instead of a number?

We can achieve this by updating our JsonOptions and register the JsonStringEnumConverter:

	builder.Services.AddControllers()
	.AddJsonOptions(opts =>
	{
	var enumConverter = new JsonStringEnumConverter();
	opts.JsonSerializerOptions.Converters.Add(enumConverter);
	});

view raw Program.cs hosted with ❤ by GitHub

If we now call our API, the result looks like this:

	{
	"date": "2022-09-25T10:52:14.8018192+02:00",
	"temperatureC": -8,
	"temperatureF": 18,
	"summary": "Scorching",
	"weatherType": "Rainy"
	}

view raw Response.json hosted with ❤ by GitHub