Github user fhueske commented on a diff in the pull request: https://github.com/apache/flink/pull/4355#discussion_r130113134 --- Diff: flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/utils/UserDefinedFunctionUtils.scala --- @@ -307,6 +312,119 @@ object UserDefinedFunctionUtils { // ---------------------------------------------------------------------------------------------- /** + * get data view type information from accumulator constructor. + * + * @param aggFun aggregate function + * @return the data view specification + */ + def getDataViewTypeInfoFromConstructor( + aggFun: AggregateFunction[_, _]) + : mutable.HashMap[String, TypeInformation[_]] = { + + val resultMap = new mutable.HashMap[String, TypeInformation[_]] + val acc = aggFun.createAccumulator() + val fields: util.List[Field] = TypeExtractor.getAllDeclaredFields(acc.getClass, true) + for (i <- 0 until fields.size()) { + val field = fields.get(i) + field.setAccessible(true) + if (classOf[DataView].isAssignableFrom(field.getType)) { + if (field.getType == classOf[MapView[_, _]]) { + val mapView = field.get(acc) + val keyTypeInfo = getFieldValue(classOf[MapView[_, _]], mapView, "keyTypeInfo") --- End diff -- If we add `private[flink]` methods to `MapView` (and ListView) to access the key and value type infos we don't need to use reflection.
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