| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| |
| package org.apache.samza.sql.fn; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| import org.apache.commons.lang3.Validate; |
| import org.apache.samza.config.Config; |
| import org.apache.samza.context.Context; |
| import org.apache.samza.sql.SamzaSqlRelRecord; |
| import org.apache.samza.sql.udfs.SamzaSqlUdf; |
| import org.apache.samza.sql.udfs.SamzaSqlUdfMethod; |
| import org.apache.samza.sql.udfs.ScalarUdf; |
| |
| |
| /** |
| * BuildOutputRecordUdf builds a SamzaSqlRelRecord with given list of key value pairs. |
| * Useful if you need to populate fields for a Kafka message. |
| * |
| * For example, given args = {k1, v1, k2, v2}, |
| * it returns a SamzaSqlRelRecord with fieldNames={k1, k2} and fieldValues={v1, v2}, |
| * where v1 or v2 can be any Object, including SamzaSqlRelRecord when you want to set nested field. |
| * |
| * Consider the below nested output schema: |
| * { |
| * field1, |
| * field2:{ |
| * field21, |
| * field22 |
| * }, |
| * field3:{ |
| * field31:{ |
| * field311, |
| * field312 |
| * }, |
| * field32 |
| * } |
| * }; |
| * It could be built in the select statement as: |
| * select obj1 as field1, |
| * BuildSamzaSqlRelRecord("field21", obj21, "field22", obj22) as field2, |
| * BuildSamzaSqlRelRecord("field31", BuildSamzaSqlRelRecord("field311", obj311, "field312", obj312), |
| * "field32", obj32) as field3 |
| * |
| * If no args is provided, it returns an empty SamzaSqlRelRecord (with empty field names and values list). |
| */ |
| |
| @SamzaSqlUdf(name = "BuildOutputRecord", description = "Creates an Output record.") |
| public class BuildOutputRecordUdf implements ScalarUdf { |
| @Override |
| public void init(Config udfConfig, Context context) { |
| } |
| |
| @SamzaSqlUdfMethod(disableArgumentCheck = true) |
| public SamzaSqlRelRecord execute(Object... args) { |
| int numOfArgs = args.length; |
| Validate.isTrue(numOfArgs % 2 == 0, "numOfArgs should be an even number"); |
| |
| List<String> fieldNames = new ArrayList<>(); |
| List<Object> fieldValues = new ArrayList<>(); |
| |
| for (int i = 0; i < numOfArgs - 1; i += 2) { |
| fieldNames.add((String) args[i]); |
| // value can be instanceof SamzaSqlRelRecord, or any Object(string, int, long most likely) |
| fieldValues.add(args[i + 1]); |
| } |
| |
| return new SamzaSqlRelRecord(fieldNames, fieldValues); |
| } |
| } |