【WIP】Deserialization support when value class is specified as a Map key

src/main/kotlin/io/github/projectmapk/jackson/module/kogera/KotlinModule.kt

@@ -79,7 +79,7 @@ public class KotlinModule private constructor(
         _deserializers = KotlinDeserializers(cache, useJavaDurationConversion)
 
         _keySerializers = KotlinKeySerializers(cache)
-        _keyDeserializers = KotlinKeyDeserializers
+        _keyDeserializers = KotlinKeyDeserializers(cache)
 
         _abstractTypes = ClosedRangeResolver
 

src/main/kotlin/io/github/projectmapk/jackson/module/kogera/deser/deserializers/KotlinKeyDeserializers.kt

@@ -4,9 +4,18 @@ import com.fasterxml.jackson.databind.BeanDescription
 import com.fasterxml.jackson.databind.DeserializationConfig
 import com.fasterxml.jackson.databind.DeserializationContext
 import com.fasterxml.jackson.databind.JavaType
+import com.fasterxml.jackson.databind.JsonMappingException
 import com.fasterxml.jackson.databind.KeyDeserializer
 import com.fasterxml.jackson.databind.deser.std.StdKeyDeserializer
+import com.fasterxml.jackson.databind.exc.InvalidDefinitionException
 import com.fasterxml.jackson.databind.module.SimpleKeyDeserializers
+import io.github.projectmapk.jackson.module.kogera.ReflectionCache
+import io.github.projectmapk.jackson.module.kogera.ValueClassBoxConverter
+import io.github.projectmapk.jackson.module.kogera.isUnboxableValueClass
+import io.github.projectmapk.jackson.module.kogera.toSignature
+import kotlinx.metadata.isSecondary
+import kotlinx.metadata.jvm.signature
+import java.lang.reflect.Method
 import java.math.BigInteger
 
 // The reason why key is treated as nullable is to match the tentative behavior of StdKeyDeserializer.
@@ -40,18 +49,74 @@ internal object ULongKeyDeserializer : StdKeyDeserializer(-1, ULong::class.java)
         key?.let { ULongChecker.readWithRangeCheck(null, BigInteger(it)) }
 }
 
-internal object KotlinKeyDeserializers : SimpleKeyDeserializers() {
-    private fun readResolve(): Any = KotlinKeyDeserializers
+// The implementation is designed to be compatible with various creators, just in case.
+internal class ValueClassKeyDeserializer<S, D : Any>(
+    private val creator: Method,
+    private val converter: ValueClassBoxConverter<S, D>
+) : KeyDeserializer() {
+    private val unboxedClass: Class<*> = creator.parameterTypes[0]
 
+    init {
+        creator.apply { if (!this.isAccessible) this.isAccessible = true }
+    }
+
+    // Based on databind error
+    // https://github.com/FasterXML/jackson-databind/blob/341f8d360a5f10b5e609d6ee0ea023bf597ce98a/src/main/java/com/fasterxml/jackson/databind/deser/DeserializerCache.java#L624
+    private fun errorMessage(boxedType: JavaType): String =
+        "Could not find (Map) Key deserializer for types wrapped in $boxedType"
+
+    override fun deserializeKey(key: String?, ctxt: DeserializationContext): Any {
+        val unboxedJavaType = ctxt.constructType(unboxedClass)
+
+        return try {
+            // findKeyDeserializer does not return null, and an exception will be thrown if not found.
+            val value = ctxt.findKeyDeserializer(unboxedJavaType, null).deserializeKey(key, ctxt)
+            @Suppress("UNCHECKED_CAST")
+            converter.convert(creator.invoke(null, value) as S)
+        } catch (e: InvalidDefinitionException) {
+            throw JsonMappingException.from(ctxt, errorMessage(ctxt.constructType(converter.boxedClass)), e)
+        }
+    }
+
+    companion object {
+        fun createOrNull(
+            valueClass: Class<*>,
+            cache: ReflectionCache
+        ): ValueClassKeyDeserializer<*, *>? {
+            val jmClass = cache.getJmClass(valueClass) ?: return null
+            val primaryKmConstructorSignature =
+                jmClass.constructors.first { !it.isSecondary }.signature
+
+            // Only primary constructor is allowed as creator, regardless of visibility.
+            // This is because it is based on the WrapsNullableValueClassBoxDeserializer.
+            // Also, as far as I could research, there was no such functionality as JsonKeyCreator,
+            // so it was not taken into account.
+            return valueClass.declaredMethods.find { it.toSignature() == primaryKmConstructorSignature }?.let {
+                val unboxedClass = it.returnType
+
+                val converter = cache.getValueClassBoxConverter(unboxedClass, valueClass)
+
+                ValueClassKeyDeserializer(it, converter)
+            }
+        }
+    }
+}
+
+internal class KotlinKeyDeserializers(private val cache: ReflectionCache) : SimpleKeyDeserializers() {
     override fun findKeyDeserializer(
         type: JavaType,
         config: DeserializationConfig?,
         beanDesc: BeanDescription?
-    ): KeyDeserializer? = when (type.rawClass) {
-        UByte::class.java -> UByteKeyDeserializer
-        UShort::class.java -> UShortKeyDeserializer
-        UInt::class.java -> UIntKeyDeserializer
-        ULong::class.java -> ULongKeyDeserializer
-        else -> null
+    ): KeyDeserializer? {
+        val rawClass = type.rawClass
+
+        return when {
+            rawClass == UByte::class.java -> UByteKeyDeserializer
+            rawClass == UShort::class.java -> UShortKeyDeserializer
+            rawClass == UInt::class.java -> UIntKeyDeserializer
+            rawClass == ULong::class.java -> ULongKeyDeserializer
+            rawClass.isUnboxableValueClass() -> ValueClassKeyDeserializer.createOrNull(rawClass, cache)
+            else -> null
+        }
     }
 }

src/test/kotlin/io/github/projectmapk/jackson/module/kogera/zIntegration/deser/valueClass/ValueClasses.kt

@@ -4,12 +4,17 @@ import com.fasterxml.jackson.core.JsonParser
 import com.fasterxml.jackson.databind.DeserializationContext
 import com.fasterxml.jackson.databind.deser.std.StdDeserializer
 import io.github.projectmapk.jackson.module.kogera.deser.WrapsNullableValueClassDeserializer
+import com.fasterxml.jackson.databind.KeyDeserializer as JacksonKeyDeserializer
 
 @JvmInline
 value class Primitive(val v: Int) {
     class Deserializer : StdDeserializer<Primitive>(Primitive::class.java) {
         override fun deserialize(p: JsonParser, ctxt: DeserializationContext): Primitive = Primitive(p.intValue + 100)
     }
+
+    class KeyDeserializer : JacksonKeyDeserializer() {
+        override fun deserializeKey(key: String, ctxt: DeserializationContext) = Primitive(key.toInt() + 100)
+    }
 }
 
 @JvmInline
@@ -18,6 +23,10 @@ value class NonNullObject(val v: String) {
         override fun deserialize(p: JsonParser, ctxt: DeserializationContext): NonNullObject =
             NonNullObject(p.valueAsString + "-deser")
     }
+
+    class KeyDeserializer : JacksonKeyDeserializer() {
+        override fun deserializeKey(key: String, ctxt: DeserializationContext) = NonNullObject("$key-deser")
+    }
 }
 
 @JvmInline
@@ -28,4 +37,8 @@ value class NullableObject(val v: String?) {
 
         override fun getBoxedNullValue(): NullableObject = NullableObject("null-value-deser")
     }
+
+    class KeyDeserializer : JacksonKeyDeserializer() {
+        override fun deserializeKey(key: String, ctxt: DeserializationContext) = NullableObject("$key-deser")
+    }
 }

src/test/kotlin/io/github/projectmapk/jackson/module/kogera/zIntegration/deser/valueClass/mapKey/WithoutCustomDeserializeMethodTest.kt

@@ -0,0 +1,117 @@
+package io.github.projectmapk.jackson.module.kogera.zIntegration.deser.valueClass.mapKey
+
+import com.fasterxml.jackson.databind.DeserializationContext
+import com.fasterxml.jackson.databind.JsonMappingException
+import com.fasterxml.jackson.databind.exc.InvalidDefinitionException
+import com.fasterxml.jackson.databind.module.SimpleModule
+import io.github.projectmapk.jackson.module.kogera.defaultMapper
+import io.github.projectmapk.jackson.module.kogera.jacksonObjectMapper
+import io.github.projectmapk.jackson.module.kogera.readValue
+import io.github.projectmapk.jackson.module.kogera.zIntegration.deser.valueClass.NonNullObject
+import io.github.projectmapk.jackson.module.kogera.zIntegration.deser.valueClass.NullableObject
+import io.github.projectmapk.jackson.module.kogera.zIntegration.deser.valueClass.Primitive
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertThrows
+import java.lang.reflect.InvocationTargetException
+import com.fasterxml.jackson.databind.KeyDeserializer as JacksonKeyDeserializer
+
+class WithoutCustomDeserializeMethodTest {
+    companion object {
+        val throwable = IllegalArgumentException("test")
+    }
+
+    @Nested
+    inner class DirectDeserialize {
+        @Test
+        fun primitive() {
+            val result = defaultMapper.readValue<Map<Primitive, String?>>("""{"1":null}""")
+            assertEquals(mapOf(Primitive(1) to null), result)
+        }
+
+        @Test
+        fun nonNullObject() {
+            val result = defaultMapper.readValue<Map<NonNullObject, String?>>("""{"foo":null}""")
+            assertEquals(mapOf(NonNullObject("foo") to null), result)
+        }
+
+        @Test
+        fun nullableObject() {
+            val result = defaultMapper.readValue<Map<NullableObject, String?>>("""{"bar":null}""")
+            assertEquals(mapOf(NullableObject("bar") to null), result)
+        }
+    }
+
+    data class Dst(
+        val p: Map<Primitive, String?>,
+        val nn: Map<NonNullObject, String?>,
+        val n: Map<NullableObject, String?>
+    )
+
+    @Test
+    fun wrapped() {
+        val src = """
+            {
+              "p":{"1":null},
+              "nn":{"foo":null},
+              "n":{"bar":null}
+            }
+        """.trimIndent()
+        val result = defaultMapper.readValue<Dst>(src)
+        val expected = Dst(
+            mapOf(Primitive(1) to null),
+            mapOf(NonNullObject("foo") to null),
+            mapOf(NullableObject("bar") to null)
+        )
+
+        assertEquals(expected, result)
+    }
+
+    @JvmInline
+    value class HasCheckConstructor(val value: Int) {
+        init {
+            if (value < 0) throw throwable
+        }
+    }
+
+    @Test
+    fun callConstructorCheckTest() {
+        val e = assertThrows<InvocationTargetException> {
+            defaultMapper.readValue<Map<HasCheckConstructor, String?>>("""{"-1":null}""")
+        }
+        assertTrue(e.cause === throwable)
+    }
+
+    data class Wrapped(val first: String, val second: String) {
+        class KeyDeserializer : JacksonKeyDeserializer() {
+            override fun deserializeKey(key: String, ctxt: DeserializationContext) =
+                key.split("-").let { Wrapped(it[0], it[1]) }
+        }
+    }
+
+    @JvmInline
+    value class Wrapper(val w: Wrapped)
+
+    @Test
+    fun wrappedCustomObject() {
+        // If a type that cannot be deserialized is specified, the default is an error.
+        val thrown = assertThrows<JsonMappingException> {
+            defaultMapper.readValue<Map<Wrapper, String?>>("""{"foo-bar":null}""")
+        }
+        assertTrue(thrown.cause is InvalidDefinitionException)
+
+        val mapper = jacksonObjectMapper()
+            .registerModule(
+                object : SimpleModule() {
+                    init { addKeyDeserializer(Wrapped::class.java, Wrapped.KeyDeserializer()) }
+                }
+            )
+
+        val result = mapper.readValue<Map<Wrapper, String?>>("""{"foo-bar":null}""")
+        val expected = mapOf(Wrapper(Wrapped("foo", "bar")) to null)
+
+        assertEquals(expected, result)
+    }
+}

src/test/kotlin/io/github/projectmapk/jackson/module/kogera/zIntegration/deser/valueClass/mapKey/keyDeserializer/SpecifiedForObjectMapperTest.kt

@@ -0,0 +1,70 @@
+package io.github.projectmapk.jackson.module.kogera.zIntegration.deser.valueClass.mapKey.keyDeserializer
+
+import com.fasterxml.jackson.databind.module.SimpleModule
+import io.github.projectmapk.jackson.module.kogera.jacksonObjectMapper
+import io.github.projectmapk.jackson.module.kogera.readValue
+import io.github.projectmapk.jackson.module.kogera.zIntegration.deser.valueClass.NonNullObject
+import io.github.projectmapk.jackson.module.kogera.zIntegration.deser.valueClass.NullableObject
+import io.github.projectmapk.jackson.module.kogera.zIntegration.deser.valueClass.Primitive
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+
+class SpecifiedForObjectMapperTest {
+    companion object {
+        val mapper = jacksonObjectMapper().apply {
+            val module = SimpleModule().apply {
+                this.addKeyDeserializer(Primitive::class.java, Primitive.KeyDeserializer())
+                this.addKeyDeserializer(NonNullObject::class.java, NonNullObject.KeyDeserializer())
+                this.addKeyDeserializer(NullableObject::class.java, NullableObject.KeyDeserializer())
+            }
+            this.registerModule(module)
+        }
+    }
+
+    @Nested
+    inner class DirectDeserialize {
+        @Test
+        fun primitive() {
+            val result = mapper.readValue<Map<Primitive, String?>>("""{"1":null}""")
+            assertEquals(mapOf(Primitive(101) to null), result)
+        }
+
+        @Test
+        fun nonNullObject() {
+            val result = mapper.readValue<Map<NonNullObject, String?>>("""{"foo":null}""")
+            assertEquals(mapOf(NonNullObject("foo-deser") to null), result)
+        }
+
+        @Test
+        fun nullableObject() {
+            val result = mapper.readValue<Map<NullableObject, String?>>("""{"bar":null}""")
+            assertEquals(mapOf(NullableObject("bar-deser") to null), result)
+        }
+    }
+
+    data class Dst(
+        val p: Map<Primitive, String?>,
+        val nn: Map<NonNullObject, String?>,
+        val n: Map<NullableObject, String?>
+    )
+
+    @Test
+    fun wrapped() {
+        val src = """
+            {
+              "p":{"1":null},
+              "nn":{"foo":null},
+              "n":{"bar":null}
+            }
+        """.trimIndent()
+        val result = mapper.readValue<Dst>(src)
+        val expected = Dst(
+            mapOf(Primitive(101) to null),
+            mapOf(NonNullObject("foo-deser") to null),
+            mapOf(NullableObject("bar-deser") to null)
+        )
+
+        assertEquals(expected, result)
+    }
+}

src/test/kotlin/io/github/projectmapk/jackson/module/kogera/zIntegration/deser/valueClass/mapKey/keyDeserializer/byAnnotation/SpecifiedForClassTest.kt

@@ -0,0 +1,37 @@
+package io.github.projectmapk.jackson.module.kogera.zIntegration.deser.valueClass.mapKey.keyDeserializer.byAnnotation
+
+import com.fasterxml.jackson.databind.DeserializationContext
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize
+import io.github.projectmapk.jackson.module.kogera.defaultMapper
+import io.github.projectmapk.jackson.module.kogera.jacksonObjectMapper
+import io.github.projectmapk.jackson.module.kogera.readValue
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+import com.fasterxml.jackson.databind.KeyDeserializer as JacksonKeyDeserializer
+
+class SpecifiedForClassTest {
+    @JsonDeserialize(keyUsing = Value.KeyDeserializer::class)
+    @JvmInline
+    value class Value(val v: Int) {
+        class KeyDeserializer : JacksonKeyDeserializer() {
+            override fun deserializeKey(key: String, ctxt: DeserializationContext) = Value(key.toInt() + 100)
+        }
+    }
+
+    @Test
+    fun directDeserTest() {
+        val result = defaultMapper.readValue<Map<Value, String?>>("""{"1":null}""")
+
+        assertEquals(mapOf(Value(101) to null), result)
+    }
+
+    data class Wrapper(val v: Map<Value, String?>)
+
+    @Test
+    fun paramDeserTest() {
+        val mapper = jacksonObjectMapper()
+        val result = mapper.readValue<Wrapper>("""{"v":{"1":null}}""")
+
+        assertEquals(Wrapper(mapOf(Value(101) to null)), result)
+    }
+}