Decode polymorphic using elementName rather than index

More in line with old code and probably more stable since we're dealing with maps

Author: Daeda88

firebase-common/src/androidMain/kotlin/dev/gitlive/firebase/_decoders.kt

@@ -32,10 +32,10 @@ actual fun getPolymorphicType(value: Any?, discriminator: String): String =
 private fun FirebaseDecoder.decodeAsMap(isNestedPolymorphic: Boolean): CompositeDecoder = (value as? Map<*, *>).orEmpty().let { map ->
     FirebaseClassDecoder(map.size, settings, { map.containsKey(it) }) { desc, index ->
         if (isNestedPolymorphic) {
-            if (index == 0)
-                map[desc.getElementName(index)]
-            else {
+            if (desc.getElementName(index) == "value")
                 map
+            else {
+                map[desc.getElementName(index)]
             }
         } else {
             map[desc.getElementName(index)]

firebase-common/src/commonTest/kotlin/dev/gitlive/firebase/EncodersTest.kt

@@ -49,12 +49,12 @@ data class GenericClass<T>(
 
 @Serializable
 abstract class AbstractClass {
-    abstract val value: String
+    abstract val abstractValue: String
 }
 
 @Serializable
 @SerialName("implemented")
-data class ImplementedClass(override val value: String, val otherValue: Boolean) : AbstractClass()
+data class ImplementedClass(override val abstractValue: String, val otherValue: Boolean) : AbstractClass()
 
 @Serializable
 data class NestedClass(
@@ -170,7 +170,7 @@ class EncodersTest {
                 serializersModule = module
             }
 
-        nativeAssertEquals(nativeMapOf("type" to "implemented", "value" to "value", "otherValue" to true), encoded)
+        nativeAssertEquals(nativeMapOf("type" to "implemented", "abstractValue" to "value", "otherValue" to true), encoded)
 
         val decoded = decode(AbstractClass.serializer(), encoded) {
             serializersModule = module
@@ -197,7 +197,7 @@ class EncodersTest {
 
         val testDataEncoded = nativeMapOf("map" to nativeMapOf("key" to "value"), "otherMap" to nativeMapOf(1 to 1), "bool" to true, "nullableBool" to null, "valueClass" to 42)
         val sealedEncoded = nativeMapOf("type" to "test", "value" to "value")
-        val abstractEncoded = nativeMapOf("type" to "implemented", "value" to "value", "otherValue" to true)
+        val abstractEncoded = nativeMapOf("type" to "implemented", "abstractValue" to "value", "otherValue" to true)
         nativeAssertEquals(
             nativeMapOf(
                 "testData" to testDataEncoded,
@@ -321,16 +321,16 @@ class EncodersTest {
 
         val reencoded = reencodeTransformation(
             AbstractClass.serializer(),
-            nativeMapOf("type" to "implemented", "value" to "value", "otherValue" to true),
+            nativeMapOf("type" to "implemented", "abstractValue" to "value", "otherValue" to true),
             builder = {
                 serializersModule = module
             }
         ) {
             assertEquals(ImplementedClass("value", true), it)
-            ImplementedClass("new-${it.value}", false)
+            ImplementedClass("new-${it.abstractValue}", false)
         }
 
-        nativeAssertEquals(nativeMapOf("type" to "implemented", "value" to "new-value", "otherValue" to false), reencoded)
+        nativeAssertEquals(nativeMapOf("type" to "implemented", "abstractValue" to "new-value", "otherValue" to false), reencoded)
     }
 
     @Test
@@ -360,7 +360,7 @@ class EncodersTest {
 
         val testDataEncoded = nativeMapOf("map" to nativeMapOf("key" to "value"), "otherMap" to nativeMapOf(1 to 1), "bool" to true, "nullableBool" to null, "valueClass" to 42)
         val sealedEncoded = nativeMapOf("type" to "test", "value" to "value")
-        val abstractEncoded = nativeMapOf("type" to "implemented", "value" to "value", "otherValue" to true)
+        val abstractEncoded = nativeMapOf("type" to "implemented", "abstractValue" to "value", "otherValue" to true)
         nativeAssertEquals(
             nativeMapOf(
                 "testData" to testDataEncoded,

firebase-common/src/iosMain/kotlin/dev/gitlive/firebase/_decoders.kt

@@ -28,10 +28,10 @@ private fun FirebaseDecoder.decodeAsList(): CompositeDecoder = (value as? List<*
 private fun FirebaseDecoder.decodeAsMap(isNestedPolymorphic: Boolean): CompositeDecoder = (value as? Map<*, *>).orEmpty().let { map ->
     FirebaseClassDecoder(map.size, settings, { map.containsKey(it) }) { desc, index ->
         if (isNestedPolymorphic) {
-            if (index == 0)
-                map[desc.getElementName(index)]
-            else {
+            if (desc.getElementName(index) == "value")
                 map
+            else {
+                map[desc.getElementName(index)]
             }
         } else {
             map[desc.getElementName(index)]

firebase-common/src/jsMain/kotlin/dev/gitlive/firebase/_decoders.kt

@@ -43,10 +43,10 @@ private fun FirebaseDecoder.decodeAsList(): CompositeDecoder = (value as Array<*
 private fun FirebaseDecoder.decodeAsMap(isNestedPolymorphic: Boolean): CompositeDecoder = (value as Json).let { json ->
     FirebaseClassDecoder(js("Object").keys(value).length as Int, settings, { json[it] != undefined }) { desc, index ->
         if (isNestedPolymorphic) {
-            if (index == 0) {
-                json[desc.getElementName(index)]
-            } else {
+            if (desc.getElementName(index) == "value") {
                 json
+            } else {
+                json[desc.getElementName(index)]
             }
         } else {
             json[desc.getElementName(index)]