Why there isn't an option to specify how to handle missing members in JsonSerializer.Deserialize

[shadow-cs]

I'm wondering why System.Text.Json deserializer just ignores properties not present in the class being deserialized (unless JsonExtensionData is used) and there isn't an option to specify the behavior.

More info: https://docs.microsoft.com/en-us/dotnet/standard/serialization/system-text-json-migrate-from-newtonsoft-how-to?pivots=dotnet-6-0#missingmemberhandling

This feature should be simple to implement by "just" adding a check to ObjectDefaultConverter<T>.ReadPropertyValue (well and possibly to some other places as well, maybe the generators, I'm not deep enough to say). I'd like to start using S.T.Json but this is a blocker to my use-case.

[ericstj]

Have a look here #37483. @eiriktsarpalis provided a workaround. #37483 (comment)

[shadow-cs]

Thanks for your response (and helping me find the issue, I got the keywords wrong and was unable to find it), I was initially thinking about using JsonExtensionData, but in the end, I decided this isn't a dealbreaker for our use case. We should be able to detect most misuses during testing which incorporates JSON Schema validation.

But this seems to be a simple enough (I hope) feature to implement that it feels unnatural to use a Dictionary and pollute the classes.

I hope the issue gets some traction...