Serialize data class to Map<String, String>?

[vikasuy]

Say I have the following data class

data class Test(val foo: String, val bar: Int)

With moshi, is there a way to serialize this to a java or kotlin Map<String, String>?
e.g. i would want the result to be the equivalent of the following in kotlin:

val t = Test("foo-value", 42)
# should serialize to the following:
mapOf(
  'foo' -> "foo-value",
  "bar" -> 42
)

In a way this is one step above the result of moshi's toJson function

[JakeWharton]

Yes you'll want to use the toJsonValue API which returns an Any.

In this case, since your type is a class, that will result in the value being a Map<String, Any>. And since your class contains only scalar values (i.e., its properties are not also objects themselves) the map values will also both be a String.

[vikasuy]

Ah good to know. Is there a way to get this to work with nested data classes as well?

data class Inner(val bar: Int)
data class Outer(val foo: String, val inner: Inner)
val test = Outer("foo-value", Inner(42))
# expected serialization
mapOf(
  "foo" -> "foo-value",
  "inner" -> "{\"bar\": 42}"
}

[JakeWharton]

Not out of the box. By default the nested object would be another Map.

You would have to write a custom adapter whose behavior was to serialize non-scalar properties to a string, apply it to your root object type, and then use that with toJsonValue.