fixup! KTOR-8436 Support for config deserialization for map and merged configs

Author: bjhham

ktor-server/ktor-server-core/common/src/io/ktor/server/config/ApplicationConfig.kt

@@ -7,7 +7,6 @@ package io.ktor.server.config
 import io.ktor.server.application.Application
 import io.ktor.util.reflect.TypeInfo
 import io.ktor.util.reflect.typeInfo
-import kotlin.reflect.typeOf
 
 /**
  * Represents an application config node
@@ -157,12 +156,11 @@ public inline fun <reified E> Application.propertyOrNull(key: String): E? =
  * Converts the application config value to the given type parameter.
  */
 public inline fun <reified E> ApplicationConfigValue.getAs(): E =
-    if (E::class == String::class) {
-        getString() as E
-    } else if (typeOf<E>() == typeOf<List<String>>()) {
-        getList() as E
-    } else {
-        getAs(typeInfo<E>()) as E
+    when (val typeInfo = typeInfo<E>()) {
+        typeInfo<String>() -> getString() as E
+        typeInfo<List<String>>() -> getList() as E
+        typeInfo<Map<String, Any?>>() -> getMap() as E
+        else -> getAs(typeInfo) as E
     }
 
 /**

ktor-server/ktor-server-core/common/src/io/ktor/server/config/MapConfigDecoder.kt

@@ -27,6 +27,17 @@ internal abstract class AbstractMapConfigDecoder(
     override fun decodeChar(): Char = decodeString().single()
     override fun decodeByte(): Byte = decodeString().toByte()
     override fun decodeShort(): Short = decodeString().toShort()
+    override fun decodeEnum(enumDescriptor: SerialDescriptor): Int =
+        enumDescriptor.getElementIndex(decodeString())
+
+    protected fun beginStructure(descriptor: SerialDescriptor, path: String): CompositeDecoder {
+        val kind = descriptor.kind as? StructureKind ?: error("Expected structure but found ${descriptor.kind}")
+        return when (kind) {
+            StructureKind.LIST -> ListMapConfigDecoder(map, path, map.listSize(path), serializersModule)
+            StructureKind.MAP -> SubMapConfigDecoder(map, path, serializersModule)
+            else -> MapConfigDecoder(map, path, serializersModule)
+        }
+    }
 }
 
 @OptIn(ExperimentalSerializationApi::class)
@@ -59,17 +70,8 @@ internal class MapConfigDecoder(
     override fun decodeString(): String = map[currentPath]
         ?: throw SerializationException("Property $currentPath not found")
 
-    override fun decodeEnum(enumDescriptor: SerialDescriptor): Int =
-        enumDescriptor.getElementIndex(decodeString())
-
-    override fun beginStructure(descriptor: SerialDescriptor): CompositeDecoder {
-        val kind = descriptor.kind as StructureKind
-        return when (kind) {
-            StructureKind.LIST -> ListMapConfigDecoder(map, currentPath, map.listSize(currentPath), serializersModule)
-            StructureKind.MAP -> SubMapConfigDecoder(map, currentPath, serializersModule)
-            else -> MapConfigDecoder(map, currentPath, serializersModule)
-        }
-    }
+    override fun beginStructure(descriptor: SerialDescriptor): CompositeDecoder =
+        beginStructure(descriptor, currentPath)
 }
 
 @OptIn(ExperimentalSerializationApi::class)
@@ -90,18 +92,8 @@ private class ListMapConfigDecoder(
         return map[key] ?: throw SerializationException("Missing list element at \"$key\"")
     }
 
-    override fun decodeEnum(enumDescriptor: SerialDescriptor): Int =
-        enumDescriptor.getElementIndex(decodeString())
-
-    override fun beginStructure(descriptor: SerialDescriptor): CompositeDecoder {
-        val currentKey = "$path.${index - 1}"
-        val kind = descriptor.kind as StructureKind
-        return when (kind) {
-            StructureKind.LIST -> ListMapConfigDecoder(map, currentKey, map.listSize(currentKey), serializersModule)
-            StructureKind.MAP -> SubMapConfigDecoder(map, currentKey, serializersModule)
-            else -> MapConfigDecoder(map, currentKey, serializersModule)
-        }
-    }
+    override fun beginStructure(descriptor: SerialDescriptor): CompositeDecoder =
+        beginStructure(descriptor, "$path.${index - 1}")
 }
 
 @OptIn(ExperimentalSerializationApi::class)
@@ -141,15 +133,8 @@ private class SubMapConfigDecoder(
         }
     }
 
-    override fun beginStructure(descriptor: SerialDescriptor): CompositeDecoder {
-        val key = "$path.$currentKey"
-        val kind = descriptor.kind as StructureKind
-        return when (kind) {
-            StructureKind.LIST -> ListMapConfigDecoder(map, key, map.listSize(key), serializersModule)
-            StructureKind.MAP -> SubMapConfigDecoder(map, key, serializersModule)
-            else -> MapConfigDecoder(map, key, serializersModule)
-        }
-    }
+    override fun beginStructure(descriptor: SerialDescriptor): CompositeDecoder =
+        beginStructure(descriptor, "$path.$currentKey")
 }
 
 private fun Map<String, String>.listSize(path: String): Int =

ktor-server/ktor-server-core/common/test/io/ktor/server/config/MapDecoderTest.kt

@@ -46,7 +46,8 @@ class MapDecoderTest {
     @Serializable
     data class EnumConfig(
         val enum: TestEnum,
-        val enumList: List<TestEnum>
+        val enumList: List<TestEnum>,
+        val enumMap: Map<String, TestEnum>
     )
 
     @Test
@@ -162,14 +163,17 @@ class MapDecoderTest {
             "enumList.size" to "3",
             "enumList.0" to "ONE",
             "enumList.1" to "TWO",
-            "enumList.2" to "THREE"
+            "enumList.2" to "THREE",
+            "enumMap.first" to "ONE",
+            "enumMap.second" to "TWO",
         )
 
         val decoder = MapConfigDecoder(map)
         val config = EnumConfig.serializer().deserialize(decoder)
 
         assertEquals(TestEnum.TWO, config.enum)
         assertEquals(listOf(TestEnum.ONE, TestEnum.TWO, TestEnum.THREE), config.enumList)
+        assertEquals(mapOf("first" to TestEnum.ONE, "second" to TestEnum.TWO), config.enumMap)
     }
 
     @Test

ktor-server/ktor-server-core/common/test/io/ktor/server/config/MergedApplicationConfigTest.kt

@@ -109,10 +109,15 @@ class MergedApplicationConfigTest {
             "nested.nested-value-2" to "value2",
             "nested.nested-value-3" to "value2",
         )
-        val merged = first.mergeWith(second).toMap()["nested"] as Map<*, *>
-        assertEquals("value1", merged["nested-value-1"])
-        assertEquals("value2", merged["nested-value-2"])
-        assertEquals("value2", merged["nested-value-3"])
+        val merged = first.mergeWith(second)
+        val nested = merged.toMap()["nested"] as Map<*, *>
+        assertEquals("value1", nested["nested-value-1"])
+        assertEquals("value2", nested["nested-value-2"])
+        assertEquals("value2", nested["nested-value-3"])
+        assertEquals(
+            merged.config("nested").toMap(),
+            merged.property("nested").getAs()
+        )
     }
 
     @Test

ktor-server/ktor-server-core/jvm/test/io/ktor/tests/config/HoconConfigTest.kt

@@ -9,8 +9,7 @@ import io.ktor.server.config.*
 import kotlinx.serialization.Serializable
 import kotlin.test.*
 
-class
-HoconConfigTest {
+class HoconConfigTest {
 
     @Test
     fun testKeysTopLevelHoconConfig() {