Apologies if this is in the worng channel ... I'm...

# kmongo

[tim]

Apologies if this is in the worng channel ... I'm using kotlinx.serialization and @Contextual to de(serialize) Instant as a Long for my ktor server and I want to de(serialize) it as a Mongo Date for db operations.

I am getting the expected behaviour when updating my document, but when I insertOne the documents instant is being serialized as a Long not a date (L22). When I later run updateOne the instant is being correctly serialised (L28). Any idea what I'm doing wrong here?

[tim]

Here's my simple test:

Untitled.kt

[tim]

Here's where I'm adding the contextual serializers for ktor

Untitled.kt

[tim]

Hmm oddly I have another Json instance somewhere else and that appears to be the cause of the issue ... not really sure why its effecting it though 🤔

[Ivan Brko]

i had a similar issue not so long ago and wrote down what caused it for me, so you can take a look

[Ivan Brko]

https://github.com/Litote/kmongo/issues/297

[tim]

I've got it to work as well but what's missing in my mental model, is where kmongo's instance of Json comes from? I explicitly configure contextual serializers for ktor, and so i understand why call.recieve<T>() can (de)serialize Instant <--> EpochMilliLong. But I don't see how to specify the contextual serializer for kmongo? Perhaps the Json { ... } configures a global singleton and so the ktor configuration block applies to both but then in that instant I would expect kmongo to serialize it as epoch milli 🤷

So how i have it working currently, is my ktor is configured as obove, I don't do anything to kmongo, and then I tag Instant as @Contextual which results in the desired behaviour

[tim]

Okay dug into the kmongo code a bit more and see how the registerSerializer function registers a contextual serializer on the kmongo side ... so now have the desired functionality with kotlinx.datetime where ktor treats it as a string and kmongo treats it as a bson date time 🥳