Fix nested array conversion (#156)

* Fix nested array conversion

* remove default in sanitize

Author: skolasan

.gitignore

@@ -4,6 +4,7 @@
 */build/
 */*.iml
 ./models/external/
+.DS_Store
 
 # Compiled class file
 *.class

hoptimator-avro/src/main/java/com/linkedin/hoptimator/avro/AvroConverter.java

@@ -62,10 +62,10 @@ public static Schema avro(String namespace, String name, RelDataType dataType) {
         case BOOLEAN:
           return createAvroTypeWithNullability(Schema.Type.BOOLEAN, dataType.isNullable());
         case ARRAY:
-          return createAvroSchemaWithNullability(Schema.createArray(avro(null, null, Objects.requireNonNull(dataType.getComponentType()))),
+          return createAvroSchemaWithNullability(Schema.createArray(avro(null, "arrayElement", Objects.requireNonNull(dataType.getComponentType()))),
               dataType.isNullable());
         case MAP:
-          return createAvroSchemaWithNullability(Schema.createMap(avro(null, null, Objects.requireNonNull(dataType.getValueType()))),
+          return createAvroSchemaWithNullability(Schema.createMap(avro(null, "mapElement", Objects.requireNonNull(dataType.getValueType()))),
               dataType.isNullable());
         case UNKNOWN:
         case NULL:

hoptimator-avro/src/test/java/com/linkedin/hoptimator/avro/AvroConverterTest.java

@@ -174,4 +174,38 @@ public void testAvroKeyPayloadSchemaPrimitiveKey() {
     assertEquals("field1", result.getValue().getFields().get(0).name());
     assertEquals("string", result.getValue().getFields().get(0).schema().getType().getName());
   }
+
+  @Test
+  public void convertsNestedArray() {
+    // Create a RelDataType with an array of structs
+    RelDataTypeFactory typeFactory = new SqlTypeFactoryImpl(RelDataTypeSystem.DEFAULT);
+
+    // Create a struct type for array elements
+    RelDataTypeFactory.Builder elementBuilder = new RelDataTypeFactory.Builder(typeFactory);
+    elementBuilder.add("field1", typeFactory.createSqlType(SqlTypeName.VARCHAR));
+    elementBuilder.add("field2", typeFactory.createSqlType(SqlTypeName.INTEGER));
+    RelDataType structType = elementBuilder.build();
+
+    // Create array of structs type
+    RelDataType arrayOfStructsType = typeFactory.createArrayType(structType, -1);
+
+    // Test with a struct containing an array of structs field
+    RelDataTypeFactory.Builder containerBuilder = new RelDataTypeFactory.Builder(typeFactory);
+    containerBuilder.add("arrayOfStructsField", arrayOfStructsType);
+    RelDataType containerType = containerBuilder.build();
+
+    Schema containerSchema = AvroConverter.avro("test", "Record", containerType);
+    assertNotNull(containerSchema);
+    assertEquals(1, containerSchema.getFields().size());
+    assertEquals("arrayOfStructsField", containerSchema.getFields().get(0).name());
+
+    Schema arrayFieldSchema = containerSchema.getFields().get(0).schema();
+    assertEquals(Schema.Type.ARRAY, arrayFieldSchema.getType());
+
+    Schema structElementSchema = arrayFieldSchema.getElementType();
+    assertEquals(Schema.Type.RECORD, structElementSchema.getType());
+    assertEquals(2, structElementSchema.getFields().size());
+    assertEquals("field1", structElementSchema.getFields().get(0).name());
+    assertEquals("field2", structElementSchema.getFields().get(1).name());
+  }
 }