kotlinmoshi

moshi nullable list fails with "required value"


The following works:

package com.squareup.moshi.problem

import com.squareup.moshi.JsonClass
import com.squareup.moshi.Moshi

@JsonClass(generateAdapter = true)
data class Foo(
        val bar: String?
)

fun main() {
    val adapter=Moshi.Builder().build().adapter<Foo>(Foo::class.java)
    adapter.fromJson("{}")
}

but when using a list it fails:

package com.squareup.moshi.problem

import com.squareup.moshi.JsonClass
import com.squareup.moshi.Moshi

@JsonClass(generateAdapter = true)
data class Foo(
        val bar: List<String>?
)

fun main() {
    val adapter=Moshi.Builder().build().adapter<Foo>(Foo::class.java)
    adapter.fromJson("{}")
}

with:

Exception in thread "main" com.squareup.moshi.JsonDataException: Required value 'bar' missing at $
        at com.squareup.moshi.internal.Util.missingProperty(Util.java:605)
        at com.squareup.moshi.problem.FooJsonAdapter.fromJson(FooJsonAdapter.kt:44)
        at com.squareup.moshi.problem.FooJsonAdapter.fromJson(FooJsonAdapter.kt:16)
        at com.squareup.moshi.internal.NullSafeJsonAdapter.fromJson(NullSafeJsonAdapter.java:40)
        at com.squareup.moshi.JsonAdapter.fromJson(JsonAdapter.java:43)
        at com.squareup.moshi.problem.MoshiProblemKt.main(MoshiProblem.kt:13)
        at com.squareup.moshi.problem.MoshiProblemKt.main(MoshiProblem.kt)

How can I make it work for a list? Here is a repo showing the problem: https://github.com/ligi/moshi_problem


Solution

  • The problem was actually this bug in moshi:

    https://github.com/square/moshi/issues/990

    hat tip @cketti for pointing me to the issue.