com.marklogic.mapreduce.functions.FieldValues Maven / Gradle / Ivy
/*
* Copyright (c) 2020 MarkLogic Corporation
*
* Licensed 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 com.marklogic.mapreduce.functions;
/**
* Wrapper class for the cts:field-values lexicon function.
* Subclass this class to generate map input based on a lexicon.
*
*
* Use this class with {@link com.marklogic.mapreduce.ValueInputFormat}.
*
*
* To generate map input using the lexicon function,
* create a subclass of this class and provide implementations
* of the methods that correspond to the function parameters you
* want to include in the call.
*
*
* For details, see "Using a Lexicon to Generate Key-Value Pairs"
* in the MarkLogic Connector for Hadoop Developer's Guide.
*
*
* @author jchen
*/
public abstract class FieldValues extends ValuesOrWordsFunction {
/**
* Get the value of the $field-names parameter to the lexicon
* function call, as an array of strings. Each string should be
* a field name.
*
* @return an array of element QNames.
*/
public abstract String[] getFieldNames();
@Override
void appendFunctionName(StringBuilder buf) {
buf.append("cts:field-values");
}
@Override
void appendNamesParams(StringBuilder buf) {
String[] fieldNames = getFieldNames();
buf.append("(");
for (int i = 0; i < fieldNames.length; i++) {
if (i > 0) {
buf.append(",");
}
buf.append(fieldNames[i]);
}
buf.append("),\n");
}
}