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

[svenjacobs]

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.

[swankjesse]

Can fix.

[fmrsabino]

Not sure if related but I'm also getting the same issue using Lists. As an example:

data class PaginatedResponse<out T>(val page: Int, val results: List<T>)

[mattbdean]

Is there a suggested workaround until this issue gets fixed?

[fmrsabino]

@thatJavaNerd I reverted to version 1.4.0

[cre8ivejp]

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

Thanks.

[swankjesse]

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

[rodly]

@swankjesse Is this fix being worked on still?

[swankjesse]

Yep.

[mradzinski]

@swankjesse Any news regarding this? Just wondering if to use Moshi 1.4.0 while this is fixed.

[ishitatsuyuki]

Ping, this issue is quite critical.

[mhf-air]

Please fix this

[blackberry2016]

Is this bug maintained by now?

[LouisCAD]

I guess the issue is not present in kotshi as this fixed issue shows: https://github.com/ansman/kotshi/issues/41

[blackberry2016]

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

[mattbdean]

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

[autonomousapps]

I can confirm that the Kotshi library solves this problem and, moreover, saves us from having to use moshi-kotlin and, therefore, saves us from kotlin-reflect, which contains >10k methods. Which is an important consideration for an Android project.

[NightlyNexus]

fixed by #475 for users of the KotlinJsonAdapterFactory.

[AllenCoder]

When to release the latest fix？

[bradynpoulsen]

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"]}