moshi: Generic Kotlin data classes cannot be (de)serialized

It seems that Moshi 1.5.0 has a problem with (de)serialization of generic data classes.

data class Test<out T>(val item: T)

data class Test2(val test: Test<String>)

The following code

val json = """{test:{item:"hello"}}"""
val moshi = Moshi.Builder()
        .add(KotlinJsonAdapterFactory())
        .build()
val data = moshi.adapter(Test2::class.java).fromJson(json)

produces the exception

java.lang.IllegalArgumentException: Expected a Class, ParameterizedType, or GenericArrayType, but <null> is of type null
  at com.squareup.moshi.Types.getRawType(Types.java:167)
  at com.squareup.moshi.ClassJsonAdapter$1.createFieldBindings(ClassJsonAdapter.java:83)
  at com.squareup.moshi.ClassJsonAdapter$1.create(ClassJsonAdapter.java:75)
  at com.squareup.moshi.Moshi.adapter(Moshi.java:100)
  at com.squareup.moshi.KotlinJsonAdapterFactory.create(KotlinJsonAdapter.kt:184)
  at com.squareup.moshi.Moshi.adapter(Moshi.java:100)
  at com.squareup.moshi.KotlinJsonAdapterFactory.create(KotlinJsonAdapter.kt:184)
  at com.squareup.moshi.Moshi.adapter(Moshi.java:100)
  at com.squareup.moshi.Moshi.adapter(Moshi.java:62)
  at com.svenjacobs.test.components.main.view.MainActivity.onCreate(MainActivity.kt:24)

This was working in Moshi 1.4.0 and before.

About this issue

Original URL
State: closed
Created 7 years ago
Reactions: 21
Comments: 19 (4 by maintainers)

Most upvoted comments

Can fix.

+20

swankjesse on May 18, 2017

fixed by #475 for users of the KotlinJsonAdapterFactory.

NightlyNexus on Apr 4, 2018

Please fix this

mhf-air on Dec 24, 2017

Yep.

swankjesse on Aug 28, 2017

I think it’s too simple. Will try to find time for it.

swankjesse on Aug 1, 2017

I can verify this has been fixed for KotlinJsonAdapter in 1.6.0-RC1 for the following sample.

data class Response<Output : Any>(
    val id: String?,
    val result: Output
)

val adapter: JsonAdapter<Response<List<String>>> = moshi.adapter(
    Types.newParameterizedType(
        Response::class.java,  
        Types.newParameterizedType(
            List::class.java, 
            String::class.java
        )
    )
)

adapter.toJson(Response("foo", listOf("bar", "baz"))) // yields: {"id":"foo","result":["bar","baz"]}

bradynpoulsen on May 10, 2018

Is this bug maintained by now?

ghost on Feb 1, 2018

What I ended up doing was using AutoValue + auto-value-moshi. You don’t need reflection so it’s gonna be a lot faster if you need to deserialize a ton of models very quickly like JRAW

mattbdean on Feb 15, 2018

For that kind of data class, use java to avoid this bug temporarily

ghost on Feb 15, 2018

Ping, this issue is quite critical.

ishitatsuyuki on Nov 8, 2017

Anyone knows when the PR above fixing this issue will be merged?

Thanks.

cre8ivejp on Jul 26, 2017