org.elasticsearch.hadoop.serialization.field.FieldExtractor Maven / Gradle / Ivy
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* 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.hadoop.serialization.field;
import org.elasticsearch.hadoop.serialization.SettingsAware;
/**
* Basic extractor (for serialization purposes) of a field. Typically used with {@link SettingsAware} for configuration/injection purposes.
*
*/
public interface FieldExtractor {
Object NOT_FOUND = new Object();
Object SKIP = new Object();
/**
* Returns the associated JSON representation for the given target.
* If the target cannot be handled, {@value #NOT_FOUND} should be returned.
* If the target cannot be handled, but is ok to skip then {@value #SKIP} should be returned.
*
*
* Take into account JSON formatting - either the value is raw and escaped down the stream or already returned in the appropriate format.
* If it is returned as a String, apply escaping otherwise make sure the processor is aware of it.
*
* @param target
* @return
*/
Object field(Object target);
}