JwtBuilder doesn't respect System.Text.Json.Serialization.JsonPropertyName attribute when deserializing into a record

[Iapetus-11]

public record UserJwtTokenPayload
{
    [JsonPropertyName("uid")]
    public uint UserId { get; set; }
    
    ...
}

I have this record and this code

var data = JwtBuilder.Create()
    .WithAlgorithm(new HMACSHA256Algorithm())
    .WithSecret(_jwtSecret)
    .MustVerifySignature()
    .Decode<UserJwtTokenPayload>(authHeader);

return data?.UserId;

In this case, data is an instance of UserJwtTokenPayload with default values because .Decode<...>(...) does not respect the [JsonPropertyName(...)] attribute.

If I were to rewrite this to use System.Text.Json, this works just fine. Example:

var data = JwtBuilder.Create()
    .WithAlgorithm(new HMACSHA256Algorithm())
    .WithSecret(_jwtSecret)
    .MustVerifySignature()
    .Decode(authHeader);

return JsonDocument.Parse(data).Deserialize<UserJwtTokenPayload>()?.UserId;

It seems that it should be respecting JsonPropertyName attributes when decoding as the library does when actually encoding.

[abatishchev]

Hi,
[JsonPropertyName] looks like a System.Text.Json attribute. Yeah, I think it is.
Jwt.Net uses Json.Net which will ignore it. You need to use its attribute [JsonProperty] to achieve the same.
Makes sense?
Or you can specify custom json serializer

jwt/src/JWT/Builder/JwtBuilder.cs

Lines 80 to 84 in 5d59adf

	public JwtBuilder WithSerializer(IJsonSerializer serializer)
	{
	_serializer = serializer;
	return this;
	}

Then ideally I'd ask you to contribute to the library and ship the implementation as an extension, see:

• Split NuGet package into few child packages to ease dependencies #76
• Replace Newtonsoft with System.Text.Json #364

[Iapetus-11]

Alright thank you, though it's still weird that it does respect the attribute when serializing.

Then ideally I'd ask you to contribute to the library and ship the implementation as an extension

Maybe, I'm still new to C#, I'll think about it.

[abatishchev]

To explain little more: those are 2 different JSON serializing libraries with their own set of attributes, what means one is unaware of the another.

[Iapetus-11]

Oh I understand that, which is why it's so weird that one library is partially respecting the attributes of another.

[abatishchev]

Sorry, it might be confusing indeed. System.Text.Json reuses some methods and attributes names from Json.Net. When the name is same it would look like one respects another.