How do I fail json deserialization if non-nullable...

# announcements

[aeruhxi]

How do I fail json deserialization if non-nullable fields are missing in json string?

[Czar]

Depends on your deserialization library

[gildor]

Gson or Moshi don’t provide such feature out of the box (because they are target Java, where you don’t have nullable types, all non-primitive types are nullable). You need some adapter for that. For example for Kotlin Data classes there are Moshi adapters: Kotshi (code generation of adapters) and moshi-kotlin (based on kotlin-reflect).
Not sure about Gson, but I used auto-value-gson to generate AutoValue adapters with such feature, but it doesn’t work with Data classes, only with AutoValue classes

[gildor]

Also, as an alternative (but experimental) solution you can take a look on kotlinx.serialization #C7A1U5PTM
It supports Kotlin nullability out of the box

[aeruhxi]

Is it a standalone thing that supports working with json?

[aeruhxi]

Would it be safe to use this in production?

[gildor]

standalone thing

What do you mean? Yes kotlinx.serialization supports Json out of the box.
But it’s experimental and under active development.

[aeruhxi]

I meant if it was supposed to work with other json lib like gson or has its own. Anyway. I got the answer. Thanks

[gildor]

No, it’s completely separate tool that generates bytecode directly on compile time from your annotated data class

[gildor]

Also it’s multiplatform and will be an official multiplatform serialization tool for Kotlin

[cedric]

@gildor @aeruhxi FYI in Klaxon, I just use default values in Kotlin to take care of that problem

[gildor]

Gson also will use default value if class has default constructor

[gildor]

@cedric But what will happen If I have non-null value in data class and Json doesn’t contain this value?

[cedric]

If you didn't specify a default value, Klaxon will throw an exception

[gildor]

yeah, make sense

[aeruhxi]

Thanks, I will consider Klaxon