Java tutorial
/* * 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.solr.response.transform; import java.io.IOException; import java.util.ArrayList; import java.util.List; import org.apache.lucene.document.Field; import org.apache.lucene.index.IndexableField; import org.apache.lucene.document.Document; import org.apache.lucene.index.Term; import org.apache.lucene.search.Filter; import org.apache.lucene.search.Query; import org.apache.lucene.search.QueryWrapperFilter; import org.apache.lucene.search.Sort; import org.apache.lucene.search.TermQuery; import org.apache.lucene.search.WildcardQuery; import org.apache.lucene.search.join.FixedBitSetCachingWrapperFilter; import org.apache.lucene.search.join.ToChildBlockJoinQuery; import org.apache.lucene.util.BytesRef; import org.apache.lucene.util.UnicodeUtil; import org.apache.solr.common.SolrDocument; import org.apache.solr.common.SolrException; import org.apache.solr.common.SolrException.ErrorCode; import org.apache.solr.common.params.SolrParams; import org.apache.solr.request.SolrQueryRequest; import org.apache.solr.response.ResponseWriterUtil; import org.apache.solr.schema.FieldType; import org.apache.solr.schema.IndexSchema; import org.apache.solr.schema.SchemaField; import org.apache.solr.search.DocIterator; import org.apache.solr.search.DocList; import org.apache.solr.search.QParser; import org.apache.solr.search.SyntaxError; /** * * @since solr 4.9 * * This transformer returns all descendants of each parent document in a flat list nested inside the parent document. * * * The "parentFilter" parameter is mandatory. * Optionally you can provide a "childFilter" param to filter out which child documents should be returned and a * "limit" param which provides an option to specify the number of child documents * to be returned per parent document. By default it's set to 10. * * Examples - * [child parentFilter="fieldName:fieldValue"] * [child parentFilter="fieldName:fieldValue" childFilter="fieldName:fieldValue"] * [child parentFilter="fieldName:fieldValue" childFilter="fieldName:fieldValue" limit=20] */ public class ChildDocTransformerFactory extends TransformerFactory { @Override public DocTransformer create(String field, SolrParams params, SolrQueryRequest req) { SchemaField uniqueKeyField = req.getSchema().getUniqueKeyField(); if (uniqueKeyField == null) { throw new SolrException(ErrorCode.BAD_REQUEST, " ChildDocTransformer requires the schema to have a uniqueKeyField."); } String parentFilter = params.get("parentFilter"); if (parentFilter == null) { throw new SolrException(ErrorCode.BAD_REQUEST, "Parent filter should be sent as parentFilter=filterCondition"); } String childFilter = params.get("childFilter"); int limit = params.getInt("limit", 10); Filter parentsFilter = null; try { Query parentFilterQuery = QParser.getParser(parentFilter, null, req).getQuery(); parentsFilter = new FixedBitSetCachingWrapperFilter(new QueryWrapperFilter(parentFilterQuery)); } catch (SyntaxError syntaxError) { throw new SolrException(ErrorCode.BAD_REQUEST, "Failed to create correct parent filter query"); } Query childFilterQuery = null; if (childFilter != null) { try { childFilterQuery = QParser.getParser(childFilter, null, req).getQuery(); } catch (SyntaxError syntaxError) { throw new SolrException(ErrorCode.BAD_REQUEST, "Failed to create correct child filter query"); } } return new ChildDocTransformer(field, parentsFilter, uniqueKeyField, req.getSchema(), childFilterQuery, limit); } } class ChildDocTransformer extends TransformerWithContext { private final String name; private final SchemaField idField; private final IndexSchema schema; private Filter parentsFilter; private Query childFilterQuery; private int limit; public ChildDocTransformer(String name, final Filter parentsFilter, final SchemaField idField, IndexSchema schema, final Query childFilterQuery, int limit) { this.name = name; this.idField = idField; this.schema = schema; this.parentsFilter = parentsFilter; this.childFilterQuery = childFilterQuery; this.limit = limit; } @Override public String getName() { return name; } @Override public void transform(SolrDocument doc, int docid) { FieldType idFt = idField.getType(); Object parentIdField = doc.getFirstValue(idField.getName()); String parentIdExt = parentIdField instanceof IndexableField ? idFt.toExternal((IndexableField) parentIdField) : parentIdField.toString(); try { Query parentQuery = idFt.getFieldQuery(null, idField, parentIdExt); Query query = new ToChildBlockJoinQuery(parentQuery, parentsFilter, false); DocList children = context.searcher.getDocList(query, childFilterQuery, new Sort(), 0, limit); if (children.matches() > 0) { DocIterator i = children.iterator(); while (i.hasNext()) { Integer childDocNum = i.next(); Document childDoc = context.searcher.doc(childDocNum); SolrDocument solrChildDoc = ResponseWriterUtil.toSolrDocument(childDoc, schema); // TODO: future enhancement... // support an fl local param in the transformer, which is used to build // a private ReturnFields instance that we use to prune unwanted field // names from solrChildDoc doc.addChildDocument(solrChildDoc); } } } catch (IOException e) { doc.put(name, "Could not fetch child Documents"); } } }