Documentation for 'explicitNulls' feature (#1634)

Fixes #1619

Co-authored-by: Sergey.Shanshin <sergey.shanshin@jetbrains.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/guide/example/example-json-20.kt b/guide/example/example-json-20.kt
new file mode 100644
index 00000000..d12547d7
--- /dev/null
+++ b/guide/example/example-json-20.kt
@@ -0,0 +1,37 @@
+// This file was automatically generated from json.md by Knit tool. Do not edit.
+package example.exampleJson20
+
+import kotlinx.serialization.*
+import kotlinx.serialization.json.*
+
+import kotlinx.serialization.descriptors.*
+import kotlinx.serialization.encoding.*
+
+data class UnknownProject(val name: String, val details: JsonObject)
+
+object UnknownProjectSerializer : KSerializer<UnknownProject> {
+    override val descriptor: SerialDescriptor = buildClassSerialDescriptor("UnknownProject") {
+        element<String>("name")
+        element<JsonElement>("details")
+    }
+
+    override fun deserialize(decoder: Decoder): UnknownProject {
+        // Cast to JSON-specific interface
+        val jsonInput = decoder as? JsonDecoder ?: error("Can be deserialized only by JSON")
+        // Read the whole content as JSON
+        val json = jsonInput.decodeJsonElement().jsonObject
+        // Extract and remove name property
+        val name = json.getValue("name").jsonPrimitive.content
+        val details = json.toMutableMap()
+        details.remove("name")
+        return UnknownProject(name, JsonObject(details))
+    }
+
+    override fun serialize(encoder: Encoder, value: UnknownProject) {
+        error("Serialization is not supported")
+    }
+}
+
+fun main() {
+    println(Json.decodeFromString(UnknownProjectSerializer, """{"type":"unknown","name":"example","maintainer":"Unknown","license":"Apache 2.0"}"""))
+}