Support decoding sets and lists

sksamuel · Apr 14, 2024 · c86dd97 · c86dd97
1 parent d91e236
commit c86dd97
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Showing 5 changed files with 61 additions and 2 deletions.
diff --git a/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/decoders/Decoder.kt b/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/decoders/Decoder.kt
@@ -31,6 +31,8 @@ fun interface Decoder<T> {
             Double::class -> DoubleDecoder
             Int::class -> IntDecoder
             Long::class -> LongDecoder
+            List::class -> ListDecoder(decoderFor(type.arguments.first().type!!))
+            Set::class -> SetDecoder(decoderFor(type.arguments.first().type!!))
             is KClass<*> -> if (classifier.java.isEnum) EnumDecoder(classifier as KClass<out Enum<*>>) else error("Unsupported type $type")
             else -> error("Unsupported type $type")
          }

diff --git a/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/decoders/collections.kt b/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/decoders/collections.kt
@@ -14,3 +14,15 @@ class ListDecoder<T>(private val decoder: Decoder<T>) : Decoder<List<T>> {
       }
    }
 }
+
+class SetDecoder<T>(private val decoder: Decoder<T>) : Decoder<Set<T>> {
+   override fun decode(schema: Schema, value: Any?): Set<T> {
+      require(schema.type == Schema.Type.ARRAY)
+      return when (value) {
+         is GenericData.Array<*> -> value.map { decoder.decode(schema.elementType, it) }.toSet()
+         is List<*> -> value.map { decoder.decode(schema.elementType, it) }.toSet()
+         is Array<*> -> value.map { decoder.decode(schema.elementType, it) }.toSet()
+         else -> error("Unsupported list type $value")
+      }
+   }
+}
diff --git a/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/decoders/nullable.kt b/centurion-avro/src/main/kotlin/com/sksamuel/centurion/avro/decoders/nullable.kt
@@ -7,7 +7,6 @@ class NullDecoder<T>(private val decoder: Decoder<T>) : Decoder<T?> {
       // nullables must be encoded with a union of 2 elements, where null is the first type
       require(schema.type == Schema.Type.UNION) { "Nulls can only be encoded with a UNION schema" }
       require(schema.types.size == 2) { "Nulls can only be encoded with a 2 element union schema" }
-      require(schema.types[0].type == Schema.Type.NULL) { "Nullable unions must have NULL as the first element type" }
-      return if (value == null) null else decoder.decode(schema, value)
+      return if (value == null) null else decoder.decode(schema.types.first { !it.isNullable }, value)
    }
 }
diff --git a/centurion-avro/src/test/kotlin/com/sksamuel/centurion/avro/decoders/NullDecoderTest.kt b/centurion-avro/src/test/kotlin/com/sksamuel/centurion/avro/decoders/NullDecoderTest.kt
@@ -0,0 +1,15 @@
+package com.sksamuel.centurion.avro.decoders
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.shouldBe
+import org.apache.avro.SchemaBuilder
+
+class NullDecoderTest : FunSpec({
+
+   test("decode null") {
+      val schema = SchemaBuilder.nullable().intType()
+      NullDecoder(IntDecoder).decode(schema, null) shouldBe null
+      NullDecoder(IntDecoder).decode(schema, 1) shouldBe 1
+   }
+
+})
diff --git a/...-avro/src/test/kotlin/com/sksamuel/centurion/avro/decoders/ReflectionRecordDecoderTest.kt b/...-avro/src/test/kotlin/com/sksamuel/centurion/avro/decoders/ReflectionRecordDecoderTest.kt
@@ -38,6 +38,7 @@ class ReflectionRecordDecoderTest : FunSpec({
 
    test("nulls") {
       data class Foo(val a: String?, val b: String)
+
       val schema = SchemaBuilder.record("Foo").fields()
          .optionalString("a")
          .requiredString("b")
@@ -49,4 +50,34 @@ class ReflectionRecordDecoderTest : FunSpec({
 
       ReflectionRecordDecoder<Foo>().decode(schema, record) shouldBe Foo(null, "hello")
    }
+
+   test("sets") {
+      data class Foo(val set1: Set<Int>, val set2: Set<Long?>)
+
+      val schema = SchemaBuilder.record("Foo").fields()
+         .name("set1").type().array().items().intType().noDefault()
+         .name("set2").type().array().items().type(SchemaBuilder.nullable().longType()).noDefault()
+         .endRecord()
+
+      val record = GenericData.Record(schema)
+      record.put("set1", listOf(1, 2))
+      record.put("set2", listOf(1, null, 2))
+
+      ReflectionRecordDecoder<Foo>().decode(schema, record) shouldBe Foo(setOf(1, 2), setOf(1L, null, 2L))
+   }
+
+   test("list") {
+      data class Foo(val list1: List<Int>, val list2: List<Long?>)
+
+      val schema = SchemaBuilder.record("Foo").fields()
+         .name("list1").type().array().items().intType().noDefault()
+         .name("list2").type().array().items().type(SchemaBuilder.nullable().longType()).noDefault()
+         .endRecord()
+
+      val record = GenericData.Record(schema)
+      record.put("list1", listOf(1, 2))
+      record.put("list2", listOf(1, null, 2))
+
+      ReflectionRecordDecoder<Foo>().decode(schema, record) shouldBe Foo(listOf(1, 2), listOf(1L, null, 2L))
+   }
 })