| /* |
| * 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.drill.metastore.mongo.transform; |
| |
| import com.google.common.collect.Maps; |
| import com.google.common.collect.Lists; |
| import org.bson.Document; |
| |
| import java.lang.invoke.MethodHandle; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.Map; |
| |
| /** |
| * Base class to convert list of {@link Document} |
| * into Metastore component units for the given list of column names. |
| * |
| * @param <T> Metastore component unit type |
| */ |
| public abstract class OutputDataTransformer<T> { |
| private final Map<String, MethodHandle> unitSetters; |
| private final List<String> columns = new ArrayList<>(); |
| private final List<Document> documents = new ArrayList<>(); |
| |
| protected OutputDataTransformer(Map<String, MethodHandle> unitSetters) { |
| this.unitSetters = unitSetters; |
| } |
| |
| public OutputDataTransformer<T> columns(List<String> columns) { |
| this.columns.addAll(columns); |
| return this; |
| } |
| |
| public OutputDataTransformer<T> documents(List<Document> documents) { |
| this.documents.addAll(documents); |
| return this; |
| } |
| |
| /** |
| * Converts given list of {@link Document} into Metastore component units. |
| * Specific for each Metastore component. |
| * |
| * @return list of Metastore component units |
| */ |
| public abstract List<T> execute(); |
| |
| /** |
| * For each given record prepares specific methods handler and its value |
| * to be set into Metastore specific component unit. |
| * Ignores absent setters for columns and null values. |
| * |
| * @return list of methods handlers and values to set |
| */ |
| protected List<Map<MethodHandle, Object>> valuesToSet() { |
| List<Map<MethodHandle, Object>> results = Lists.newLinkedList(); |
| for (Document doc : documents) { |
| Map<MethodHandle, Object> handlerMap = Maps.newHashMap(); |
| for (Map.Entry<String, Object> entry : doc.entrySet()) { |
| if (unitSetters.containsKey(entry.getKey()) |
| && (columns.isEmpty() || columns.contains(entry.getKey()))) { |
| handlerMap.put(unitSetters.get(entry.getKey()), entry.getValue()); |
| } |
| } |
| if (!handlerMap.isEmpty()) { |
| results.add(handlerMap); |
| } |
| } |
| return results; |
| } |
| } |