Missing support of parsing `immutable.IntMap` and `mutable.LongMap`

[plokhotnyuk]

In case of parsing jackson-module-scala throws java.lang.IllegalArgumentException: Need exactly 2 type parameters for map like types while serialization works as expected.

[pjfanning]

Thanks for reporting this. I've added tests for serialization - IntMap/LongMap were not tested anywhere in the test suite.

Adding a fix for deserialization might be tricky - based on how the code currently works. When I recently added BitSet deserialization support, the solution was quite hacky.

[cowtowncoder]

I don't have much context or anything, but I think Scala module already creates MapLikeTypes for other Map-like (but not implementing java.util.Map) types with custom TypeModifier. So the specific symptom can possibly be fixed without too much trouble assuming modifier can easily know/detect both key and value types (instead of having to point to Class that has 2 type parameters).

[pjfanning]

I have got basic support merged to 2.14 branch now. There are shortcomings for types like IntMap[Long] as the code the inner type (Long) is erased by the time Jackson's Java reflection based code gets to introspect it. I'll come back to that later.

[plokhotnyuk]

I tried with the latest snapshot version and got following errors:

[info]   com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `scala.collection.mutable.LongMap<boolean>` from Object value (token `JsonToken.START_OBJECT`)
[info]  at [Source: (byte[])"{"-900845381675988":true,"-654142214247":false,"-45042269083799408":true,"-407439046":true,"4934063348569":true,"2467031674284864":false,"4298364401":true,"7401095022":false,"-20371952340950":false,"697125858266480539":false}"; line: 1, column: 1]
[info]   at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59)
[info]   at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1746)
[info]   at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1520)
[info]   at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1467)
[info]   at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.handleNonArray(CollectionDeserializer.java:396)
[info]   at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:252)
[info]   at com.fasterxml.jackson.module.scala.deser.GenericFactoryDeserializerResolver$Deserializer.deserialize(GenericFactoryDeserializerResolver.scala:125)
[info]   at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootValue(DefaultDeserializationContext.java:323)
[info]   at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4697)
[info]   at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3746)
[info]   at com.fasterxml.jackson.module.scala.ClassTagExtensions.readValue(ClassTagExtensions.scala:147)
[info]   at com.fasterxml.jackson.module.scala.ClassTagExtensions.readValue$(ClassTagExtensions.scala:146)

[info]   com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `scala.collection.immutable.IntMap<boolean>` from Object value (token `JsonToken.START_OBJECT`)
[info]  at [Source: (byte[])"{"0":false,"190":false,"402":true,"169992":true,"201204":false,"149872405":false,"2102338642":true,"-12975191":true,"-10963":false,"-8":true}"; line: 1, column: 1]
[info]   at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59)
[info]   at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1746)
[info]   at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1520)
[info]   at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1467)
[info]   at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.handleNonArray(CollectionDeserializer.java:396)
[info]   at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:252)
[info]   at com.fasterxml.jackson.module.scala.deser.GenericFactoryDeserializerResolver$Deserializer.deserialize(GenericFactoryDeserializerResolver.scala:125)
[info]   at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootValue(DefaultDeserializationContext.java:323)
[info]   at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4697)
[info]   at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3746)
[info]   at com.fasterxml.jackson.module.scala.ClassTagExtensions.readValue(ClassTagExtensions.scala:147)
[info]   at com.fasterxml.jackson.module.scala.ClassTagExtensions.readValue$(ClassTagExtensions.scala:146)

[pjfanning]

Thanks for checking @plokhotnyuk

Could you try jacksonMapper.readValue(jsonBytes, new TypeReference[IntMap[Boolean]] {}) instead of jacksonMapper.readValue[IntMap[Boolean]](jsonBytes)? This change seems to work for me. I'll look into why the other form fails.

[pjfanning]

@plokhotnyuk I think I've fixed the issue with ClassTagExtensions - the readValue[IntMap[Boolean]](jsonBytes) function should now be ok.

[plokhotnyuk]

@pjfanning Thanks a lot! Both approaches works for me in the latest snapshot.

@cowtowncoder Could you please cut a milestone version for 2.14 branch of Jackson?

[cowtowncoder]

@plokhotnyuk I am hoping to close issues to be able to do that but cannot really promise a concrete day. I suspect 2.14.0-rc1 will get out sometime early September.