RESTProvider.java

/**
 * Copyright (C) 2013 Isabel Drost-Fromm
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of 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 de.isabeldrostfromm.sof.naive;

import io.searchbox.client.JestClient;
import io.searchbox.client.JestResult;
import io.searchbox.core.Search;

import java.util.HashMap;
import java.util.Iterator;

import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;

import com.google.gson.internal.StringMap;

import de.isabeldrostfromm.sof.Example;
import de.isabeldrostfromm.sof.ExampleProvider;
import de.isabeldrostfromm.sof.GenericRESTProvider;

/**
 * Provides query capabilities through the ES REST interface.
 * TODO tests missing
 * */
@SuppressWarnings("rawtypes")
public class RESTProvider extends GenericRESTProvider {

    private RESTProvider(JestClient client, QueryBuilder qbuilder, int start, int total) {
        super(client, qbuilder, start, total);
	}

    /**
     * Returns a document provider that provides documents that match the string value in the given field.
     * @param field the field to search for terms
     * @param value the term to search for in field
     * @param start first hit position to consider
     * @param total total number of hits to return
     * @return fully initiated document provider
     * */
    public static ExampleProvider filterInstance(String field, String value, int start, int total) {
        QueryBuilder qbuilder = QueryBuilders.termQuery(field, value);
        return instance(qbuilder, start, total);
    }

    
    /**
     * Returns a document provider that provides documents that do *NOT* match the string value in the given field.
     * @param field the field to search for terms
     * @param value the term to search for in field
     * @param start first hit position to consider
     * @param total total number of hits to return
     * @return fully initiated document provider
     * */
    public static ExampleProvider negatedFilterInstance(String field, String value, int start, int total) {
        QueryBuilder qbuilder = QueryBuilders.boolQuery().mustNot(QueryBuilders.termQuery(field, value));
        return instance(qbuilder, start, total);
    }

    public static ExampleProvider instance(QueryBuilder qbuilder, int start, int total) {
		return new RESTProvider(initClient(), qbuilder, start, total); 
	}

	/**
	 * Each call to this method will initiate a new query to elastic search and return
	 * the resulting hits (given the search parameter the Provider was initialized with.
	 * */
	@Override
	public Iterator<Example> iterator() {
		Search search = new Search(Search.createQueryWithBuilder(this.qbuilder.toString()));
		search.addParameter("from", this.start);
		search.addParameter("size", this.total); 
		search.addParameter("sort", "post_creation_date");
		search.addIndex("sof-sample");
		JestResult result;
		try {
			result = this.client.execute(search);
		} catch (Exception e) {
			return new RESTProviderIterator(new HashMap<String, StringMap>());
		}
		@SuppressWarnings("unchecked")
		RESTProviderIterator iter = new RESTProviderIterator(result.getJsonMap());
		return iter;
	}
}