fr.imag.unql.transformation.util.MongoDBUtil.java Source code

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Here is the source code for fr.imag.unql.transformation.util.MongoDBUtil.java

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/**
 * Copyright 2013 jccastrejon
 * 
 * This file is part of EDBT-unql.
 * EDBT-unql is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 * 
 * EDBT-unql is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with EDBT-unql.  If not, see <http://www.gnu.org/licenses/>.
 */
package fr.imag.unql.transformation.util;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.MongoClient;

/**
 * Allows the execution of queries in MongoDB databases.
 * 
 * @author jccastrejon
 * 
 */
public class MongoDBUtil implements DatabaseUtil {

    @Override
    public String executeQuery(final String relationName, final String connectionURL,
            final String connectionUsername, final String connectionPassword, final List<String> attributes,
            final List<String> conditions) {
        DB database;
        DBCursor queryResults;
        DBCollection collection;
        MongoClient mongoClient;
        StringBuilder returnValue;
        BasicDBObject searchQuery;
        BasicDBObject searchAttributes;

        returnValue = new StringBuilder();
        Map<String, String> conditionsMap;
        Map<String, String> attributesMap;

        try {
            searchQuery = new BasicDBObject();
            searchAttributes = new BasicDBObject();
            mongoClient = new MongoClient(connectionURL);
            database = mongoClient.getDB(relationName);

            // Database connection
            if ((connectionUsername != null) && (connectionPassword != null)) {
                database.authenticate(connectionUsername, connectionPassword.toCharArray());
            }

            // Format attributes that will be projected
            attributesMap = this.getAttributesMap(relationName, attributes);
            for (String key : attributesMap.keySet()) {
                searchAttributes.put(key, attributesMap.get(key));
            }

            // Format conditions that will be applied
            conditionsMap = this.getConditionsMap(relationName, conditions);
            for (String key : conditionsMap.keySet()) {
                searchQuery.put(key, conditionsMap.get(key));
            }

            // Execute query and retrieve results
            collection = database.getCollection(relationName);
            queryResults = collection.find(searchQuery, searchAttributes);
            while (queryResults.hasNext()) {
                returnValue.append(queryResults.next()).append("\n");
            }
        } catch (Exception e) {
            returnValue.append("Error while executing MongoDB query: " + e.getMessage());
        }

        return returnValue.toString();
    }

    /**
     * Format attributes that will be projected.
     * 
     * @param relationName
     * @param attributes
     * @return
     */
    private Map<String, String> getAttributesMap(final String relationName, final List<String> attributes) {
        Map<String, String> returnValue;

        returnValue = new HashMap<String, String>();
        if (attributes != null) {
            for (String attribute : attributes) {
                returnValue.put(attribute.replace(relationName + ".", ""), "1");
            }
        }

        return returnValue;
    }

    /**
     * Format conditions that will be applied. - TODO: Refactor with
     * getAttributesMap()
     * 
     * @param relationName
     * @param conditions
     * @return
     */
    private Map<String, String> getConditionsMap(final String relationName, final List<String> conditions) {
        String key;
        String value;
        int operatorIndex;
        Map<String, String> returnValue;

        returnValue = new HashMap<String, String>();
        if (conditions != null) {
            for (String condition : conditions) {
                operatorIndex = condition.indexOf('=');
                key = condition.substring(0, operatorIndex).replace(relationName + ".", "").trim();
                value = condition.substring(operatorIndex + 1, condition.length()).replace("'", "")
                        .replace(relationName + ".", "").trim();
                returnValue.put(key, value);
            }
        }

        return returnValue;
    }
}