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Fix bson-kotlinx encodeNullableSerializableValue null handling #1453

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merged 4 commits into from
Jul 29, 2024
Merged

Fix bson-kotlinx encodeNullableSerializableValue null handling #1453

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53b12aa
Fix bson-kotlinx `encodeNullableSerializableValue` null handling
rozza Jul 17, 2024
62e6d0b
Cleanup deferredElementName use
rozza Jul 24, 2024
081b413
Encapsulate deferred element name handling
rozza Jul 24, 2024
ed561b5
Add comment regarding why value could be null
rozza Jul 25, 2024
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16 changes: 16 additions & 0 deletions bson-kotlin/src/test/kotlin/org/bson/codecs/kotlin/DataClassCodecTest.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ import org.bson.codecs.configuration.CodecConfigurationException
import org.bson.codecs.configuration.CodecRegistries.fromProviders
import org.bson.codecs.kotlin.samples.Box
import org.bson.codecs.kotlin.samples.DataClassEmbedded
import org.bson.codecs.kotlin.samples.DataClassLastItemDefaultsToNull
import org.bson.codecs.kotlin.samples.DataClassListOfDataClasses
import org.bson.codecs.kotlin.samples.DataClassListOfListOfDataClasses
import org.bson.codecs.kotlin.samples.DataClassListOfSealed
Expand All @@ -51,6 +52,7 @@ import org.bson.codecs.kotlin.samples.DataClassWithEnum
import org.bson.codecs.kotlin.samples.DataClassWithEnumMapKey
import org.bson.codecs.kotlin.samples.DataClassWithFailingInit
import org.bson.codecs.kotlin.samples.DataClassWithInvalidBsonRepresentation
import org.bson.codecs.kotlin.samples.DataClassWithListThatLastItemDefaultsToNull
import org.bson.codecs.kotlin.samples.DataClassWithMutableList
import org.bson.codecs.kotlin.samples.DataClassWithMutableMap
import org.bson.codecs.kotlin.samples.DataClassWithMutableSet
Expand Down Expand Up @@ -133,6 +135,20 @@ class DataClassCodecTest {
assertDecodesTo(withStoredNulls, dataClass)
}

@Test
fun testDataClassWithListThatLastItemDefaultsToNull() {
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This is just a copy from bson-kotlinx - to ensure the bson-kotlin library also works as expected.

val expected =
"""{
| "elements": [{"required": "required"}, {"required": "required"}],
|}"""
.trimMargin()

val dataClass =
DataClassWithListThatLastItemDefaultsToNull(
listOf(DataClassLastItemDefaultsToNull("required"), DataClassLastItemDefaultsToNull("required")))
assertRoundTrips(expected, dataClass)
}

@Test
fun testDataClassWithNullableGenericsNotNull() {
val expected =
Expand Down
4 changes: 4 additions & 0 deletions bson-kotlin/src/test/kotlin/org/bson/codecs/kotlin/samples/DataClasses.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,10 @@ data class DataClassWithDefaults(

data class DataClassWithNulls(val boolean: Boolean?, val string: String?, val listSimple: List<String?>?)

data class DataClassWithListThatLastItemDefaultsToNull(val elements: List<DataClassLastItemDefaultsToNull>)

data class DataClassLastItemDefaultsToNull(val required: String, val optional: String? = null)

data class DataClassSelfReferential(
val name: String,
val left: DataClassSelfReferential? = null,
Expand Down
67 changes: 40 additions & 27 deletions bson-kotlinx/src/main/kotlin/org/bson/codecs/kotlinx/BsonEncoder.kt
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Expand Up @@ -72,7 +72,7 @@ internal class DefaultBsonEncoder(
private var isPolymorphic = false
private var state = STATE.VALUE
private var mapState = MapState()
private var deferredElementName: String? = null
private val deferredElementHandler: DeferredElementHandler = DeferredElementHandler()

override fun shouldEncodeElementDefault(descriptor: SerialDescriptor, index: Int): Boolean =
configuration.encodeDefaults
Expand Down Expand Up @@ -117,7 +117,7 @@ internal class DefaultBsonEncoder(
is StructureKind.CLASS -> {
val elementName = descriptor.getElementName(index)
if (descriptor.getElementDescriptor(index).isNullable) {
deferredElementName = elementName
deferredElementHandler.set(elementName)
} else {
encodeName(elementName)
}
Expand All @@ -140,25 +140,25 @@ internal class DefaultBsonEncoder(
}

override fun <T> encodeSerializableValue(serializer: SerializationStrategy<T>, value: T) {
deferredElementName?.let {
if (value != null || configuration.explicitNulls) {
encodeName(it)
super.encodeSerializableValue(serializer, value)
} else {
deferredElementName = null
}
}
?: super.encodeSerializableValue(serializer, value)
deferredElementHandler.with(
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It's unclear to me why value is

{
if (value != null || configuration.explicitNulls) {
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Just a point of clarification:

It's unclear to me why value is ever null here. If it is, why isn't encodeNullableSerializableValue called instead?

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Yes, this surprised me also. The only test that triggers this is via the use of generics which aren't marked as nullable.

@Serializable data class Box<T>(val boxed: T)

@Serializable data class DataClassWithNullableGeneric(val box: Box<String?>)

Encoding: DataClassWithNullableGeneric(Box(null)) causes this to branch to trigger.

Its questionable that this code is reasonable / bug free. However, it appears to be marked as designed: https://youtrack.jetbrains.com/issue/KT-66206

I've added a comment to the code.

encodeName(it)
super.encodeSerializableValue(serializer, value)
}
},
{ super.encodeSerializableValue(serializer, value) })
}

override fun <T : Any> encodeNullableSerializableValue(serializer: SerializationStrategy<T>, value: T?) {
deferredElementName?.let {
if (value != null || configuration.explicitNulls) {
encodeName(it)
super.encodeNullableSerializableValue(serializer, value)
}
}
?: super.encodeNullableSerializableValue(serializer, value)
deferredElementHandler.with(
{
if (value != null || configuration.explicitNulls) {
encodeName(it)
super.encodeNullableSerializableValue(serializer, value)
}
},
{ super.encodeNullableSerializableValue(serializer, value) })
}

override fun encodeByte(value: Byte) = encodeInt(value.toInt())
Expand All @@ -170,14 +170,7 @@ internal class DefaultBsonEncoder(
override fun encodeDouble(value: Double) = writer.writeDouble(value)
override fun encodeInt(value: Int) = writer.writeInt32(value)
override fun encodeLong(value: Long) = writer.writeInt64(value)
override fun encodeNull() {
deferredElementName?.let {
if (configuration.explicitNulls) {
encodeName(it)
}
}
writer.writeNull()
}
override fun encodeNull() = writer.writeNull()
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@rozza rozza Jul 24, 2024 •
edited
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Not sure how this was missed in a PR - but encoding null will never require the deferred element name - as encode(Nullable)SerializableValue will be used


override fun encodeString(value: String) {
when (state) {
Expand Down Expand Up @@ -206,7 +199,6 @@ internal class DefaultBsonEncoder(

private fun encodeName(value: Any) {
writer.writeName(value.toString())
deferredElementName = null
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No longer required - as its cleaned up in the SerializableValue usages

state = STATE.VALUE
}

Expand All @@ -229,4 +221,25 @@ internal class DefaultBsonEncoder(
return getState()
}
}

private class DeferredElementHandler {
private var deferredElementName: String? = null

fun set(name: String) {
assert(deferredElementName == null) { -> "Overwriting an existing deferred name" }
deferredElementName = name
}

fun with(actionWithDeferredElement: (String) -> Unit, actionWithoutDeferredElement: () -> Unit): Unit {
deferredElementName?.let {
reset()
actionWithDeferredElement(it)
}
?: actionWithoutDeferredElement()
}

private fun reset() {
deferredElementName = null
}
}
}
23 changes: 23 additions & 0 deletions bson-kotlinx/src/test/kotlin/org/bson/codecs/kotlinx/KotlinSerializerCodecTest.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,7 @@ import org.bson.codecs.kotlinx.samples.DataClassContainsOpen
import org.bson.codecs.kotlinx.samples.DataClassContainsValueClass
import org.bson.codecs.kotlinx.samples.DataClassEmbedded
import org.bson.codecs.kotlinx.samples.DataClassKey
import org.bson.codecs.kotlinx.samples.DataClassLastItemDefaultsToNull
import org.bson.codecs.kotlinx.samples.DataClassListOfDataClasses
import org.bson.codecs.kotlinx.samples.DataClassListOfListOfDataClasses
import org.bson.codecs.kotlinx.samples.DataClassListOfSealed
Expand Down Expand Up @@ -78,6 +79,7 @@ import org.bson.codecs.kotlinx.samples.DataClassWithEncodeDefault
import org.bson.codecs.kotlinx.samples.DataClassWithEnum
import org.bson.codecs.kotlinx.samples.DataClassWithEnumMapKey
import org.bson.codecs.kotlinx.samples.DataClassWithFailingInit
import org.bson.codecs.kotlinx.samples.DataClassWithListThatLastItemDefaultsToNull
import org.bson.codecs.kotlinx.samples.DataClassWithMutableList
import org.bson.codecs.kotlinx.samples.DataClassWithMutableMap
import org.bson.codecs.kotlinx.samples.DataClassWithMutableSet
Expand Down Expand Up @@ -255,6 +257,27 @@ class KotlinSerializerCodecTest {
assertRoundTrips(expectedNulls, dataClass, altConfiguration)
}

@Test
fun testDataClassWithListThatLastItemDefaultsToNull() {
val expectedWithOutNulls =
"""{
| "elements": [{"required": "required"}, {"required": "required"}],
|}"""
.trimMargin()

val dataClass =
DataClassWithListThatLastItemDefaultsToNull(
listOf(DataClassLastItemDefaultsToNull("required"), DataClassLastItemDefaultsToNull("required")))
assertRoundTrips(expectedWithOutNulls, dataClass)

val expectedWithNulls =
"""{
| "elements": [{"required": "required", "optional": null}, {"required": "required", "optional": null}],
|}"""
.trimMargin()
assertRoundTrips(expectedWithNulls, dataClass, BsonConfiguration(explicitNulls = true))
}

@Test
fun testDataClassWithNullableGenericsNotNull() {
val expected =
Expand Down
5 changes: 5 additions & 0 deletions bson-kotlinx/src/test/kotlin/org/bson/codecs/kotlinx/samples/DataClasses.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,11 @@ data class DataClassWithDefaults(

@Serializable data class DataClassWithNulls(val boolean: Boolean?, val string: String?, val listSimple: List<String?>?)

@Serializable
data class DataClassWithListThatLastItemDefaultsToNull(val elements: List<DataClassLastItemDefaultsToNull>)

@Serializable data class DataClassLastItemDefaultsToNull(val required: String, val optional: String? = null)

@Serializable
data class DataClassSelfReferential(
val name: String,
Expand Down