org.apache.gora.mongodb.query.MongoDBResult.java Source code

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Here is the source code for org.apache.gora.mongodb.query.MongoDBResult.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.apache.gora.mongodb.query;

import java.io.IOException;

import org.apache.gora.mongodb.store.MongoStore;
import org.apache.gora.persistency.impl.PersistentBase;
import org.apache.gora.query.Query;
import org.apache.gora.query.impl.ResultBase;
import org.apache.gora.store.DataStore;

import com.mongodb.DBCursor;
import com.mongodb.DBObject;

/**
 * MongoDB specific implementation of the {@link org.apache.gora.query.Result}
 * interface.
 *
 * @author Fabien Poulard <fpoulard@dictanova.com>
 * @author Damien Raude-Morvan <draudemorvan@dictanova.com>
 */
public class MongoDBResult<K, T extends PersistentBase> extends ResultBase<K, T> {

    /**
     * Reference to the cursor pointing to the results
     */
    private DBCursor cursor;
    private int size;

    public MongoDBResult(DataStore<K, T> dataStore, Query<K, T> query) {
        super(dataStore, query);
    }

    @Override
    public float getProgress() throws IOException {
        if (cursor == null) {
            return 0;
        } else if (size == 0) {
            return 1;
        } else {
            return offset / (float) size;
        }
    }

    @Override
    public void close() throws IOException {
        if (cursor != null) {
            cursor.close();
        }
    }

    @Override
    protected boolean nextInner() throws IOException {
        if (!cursor.hasNext()) {
            return false;
        }

        DBObject obj = cursor.next();
        key = (K) obj.get("_id");
        persistent = ((MongoStore<K, T>) getDataStore()).newInstance(obj, getQuery().getFields());
        return persistent != null;
    }

    /**
     * Save the reference to the cursor that holds the actual results.
     *
     * @param cursor
     *          {@link DBCursor} obtained from a query execution and that holds
     *          the actual results
     */
    public void setCursor(DBCursor cursor) {
        this.cursor = cursor;
        this.size = cursor.size();
    }
}