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Elasticsearch module: parent-join
/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.join.mapper;
import org.apache.lucene.document.FieldType;
import org.apache.lucene.index.IndexOptions;
import org.apache.lucene.search.Query;
import org.apache.lucene.util.BytesRef;
import org.elasticsearch.index.fielddata.IndexFieldData;
import org.elasticsearch.index.fielddata.plain.SortedSetOrdinalsIndexFieldData;
import org.elasticsearch.index.mapper.FieldMapper;
import org.elasticsearch.index.mapper.ParseContext;
import org.elasticsearch.index.mapper.StringFieldType;
import org.elasticsearch.index.mapper.TextSearchInfo;
import org.elasticsearch.index.query.QueryShardContext;
import org.elasticsearch.search.aggregations.support.CoreValuesSourceType;
import java.io.IOException;
import java.util.Collections;
import java.util.List;
/**
* Simple field mapper hack to ensure that there is a one and only {@link ParentJoinFieldMapper} per mapping.
* This field mapper is not used to index or query any data, it is used as a marker in the mapping that
* denotes the presence of a parent-join field and forbids the addition of any additional ones.
* This class is also used to quickly retrieve the parent-join field defined in a mapping without
* specifying the name of the field.
*/
public class MetaJoinFieldMapper extends FieldMapper {
static final String NAME = "_parent_join";
static final String CONTENT_TYPE = "parent_join";
static class Defaults {
public static final FieldType FIELD_TYPE = new FieldType();
static {
FIELD_TYPE.setStored(false);
FIELD_TYPE.setIndexOptions(IndexOptions.NONE);
FIELD_TYPE.freeze();
}
}
static class Builder extends FieldMapper.Builder {
final String joinField;
Builder(String joinField) {
super(NAME, Defaults.FIELD_TYPE);
builder = this;
this.joinField = joinField;
}
@Override
public MetaJoinFieldMapper build(BuilderContext context) {
return new MetaJoinFieldMapper(name, joinField);
}
}
public static class MetaJoinFieldType extends StringFieldType {
private final String joinField;
MetaJoinFieldType(String joinField) {
super(NAME, false, false, TextSearchInfo.SIMPLE_MATCH_ONLY, Collections.emptyMap());
this.joinField = joinField;
}
@Override
public String typeName() {
return CONTENT_TYPE;
}
@Override
public IndexFieldData.Builder fielddataBuilder(String fullyQualifiedIndexName) {
failIfNoDocValues();
return new SortedSetOrdinalsIndexFieldData.Builder(CoreValuesSourceType.BYTES);
}
@Override
public Object valueForDisplay(Object value) {
if (value == null) {
return null;
}
BytesRef binaryValue = (BytesRef) value;
return binaryValue.utf8ToString();
}
public String getJoinField() {
return joinField;
}
@Override
public Query existsQuery(QueryShardContext context) {
throw new UnsupportedOperationException("Exists query not supported for fields of type" + typeName());
}
}
MetaJoinFieldMapper(String name, String joinField) {
super(name, Defaults.FIELD_TYPE, new MetaJoinFieldType(joinField), MultiFields.empty(), CopyTo.empty());
}
@Override
public MetaJoinFieldType fieldType() {
return (MetaJoinFieldType) super.fieldType();
}
@Override
protected MetaJoinFieldMapper clone() {
return (MetaJoinFieldMapper) super.clone();
}
@Override
protected void mergeOptions(FieldMapper other, List conflicts) {
}
@Override
protected void parseCreateField(ParseContext context) throws IOException {
throw new IllegalStateException("Should never be called");
}
@Override
protected String contentType() {
return CONTENT_TYPE;
}
}
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