I have a .NET 6 program that needs to deserialize a JSON string value (returned by external API) into a .NET enum.
The issue is that there are over 100 possible enum values (and more could be added without my knowledge), but I m only interested in a few of them. So I would like to define an enum type like this and deserialize all the values that I m not interested in to MyEnum.Unknown:
public enum MyEnum
{
Unknown = 0,
Value1,
Value2,
Value3,
// only values that I m interested in will be defined
}
If I m using Newtonsoft.Json, I can do this quite easily with a custom JSON converter:
public class DefaultFallbackStringEnumConverter : StringEnumConverter
{
private readonly object _defaultValue;
public DefaultFallbackStringEnumConverter() : this(0)
{
}
public DefaultFallbackStringEnumConverter(object defaultValue)
{
_defaultValue = defaultValue;
}
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
try
{
return base.ReadJson(reader, objectType, existingValue, serializer);
}
catch (JsonException)
{
return _defaultValue;
}
}
}
But with System.Text.Json, I can t figure out how this can be done easily, because the JsonStringEnumConverter in STJ is actually a JsonConverterFactory that doesn t do the serialization itself (it throws exceptions in all overrides of JsonConverter as you can see here). Instead the factory creates EnumConverter<T>s that actually do the work, but EnumConverter<T> is internal so I can t even reference or inherit from it in user code.
Any idea how this can be done easily with STJ or is it not possible at all? Thanks a lot for the help!