wip

ks3-standard/src/commonMain/kotlin/io/ks3/standard/LenientJsonPropertySerializer.kt

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+package io.ks3.standard
+
+import kotlinx.serialization.KSerializer
+import kotlinx.serialization.SerializationException
+import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
+import kotlinx.serialization.json.JsonDecoder
+import kotlinx.serialization.serializer
+
+/**
+ * Creates a serializer that will parse a JSON property into a [T] element, or `null` if the element fails to parse.
+ */
+inline fun <reified T> lenientJsonPropertyDeserializer(explicitElementSerializer: KSerializer<T>? = null) =
+   object : KSerializer<T?> {
+      private val elementSerializer = explicitElementSerializer ?: serializer<T>()
+      override val descriptor: SerialDescriptor = elementSerializer.descriptor
+
+      override fun deserialize(decoder: Decoder): T? {
+         require(decoder is JsonDecoder) { "This deserializer can only be used with Json" }
+         val json = decoder.json
+         val item = decoder.decodeJsonElement()
+         return try {
+            json.decodeFromJsonElement(elementSerializer, item)
+         } catch (e: SerializationException) {
+            null
+         } catch (e: IllegalArgumentException) {
+            null
+         }
+      }
+
+      override fun serialize(
+         encoder: Encoder,
+         value: T?,
+      ): Unit = error("Can only be used for deserialization")
+   }

ks3-standard/src/commonTest/kotlin/io/ks3/standard/LenientJsonPropertySerializerTest.kt

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+package io.ks3.standard
+
+import io.kotest.core.spec.style.StringSpec
+import io.kotest.matchers.shouldBe
+import kotlinx.serialization.KSerializer
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.Json
+
+private object LenientIntParser : KSerializer<Int?> by lenientJsonPropertyDeserializer()
+
+private typealias LenientInt =
+   @Serializable(with = LenientIntParser::class)
+   Int?
+
+class LenientJsonPropertySerializerTest : StringSpec(
+   {
+      @Serializable
+      data class Foo(
+         val bar: String,
+         val baz: LenientInt,
+      )
+
+      "Invalid value is discarded" {
+         Json.decodeFromString<Foo>("""{"bar": "bar", "baz": "x"}""") shouldBe Foo("bar", null)
+      }
+   },
+)