in.mtap.iincube.mongoapi.MongoReader.java Source code

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Here is the source code for in.mtap.iincube.mongoapi.MongoReader.java

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/*
 * Copyright 2015 mtap technologies
 *
 * 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 in.mtap.iincube.mongoapi;

import com.mongodb.BasicDBObject;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;

import java.util.LinkedList;
import java.util.List;

import static in.mtap.iincube.mongoapi.internal.Utility.assertNotNull;

public class MongoReader {
    private final MongoObjectFactory<DBCollection> collectionFactory;
    private int skip;
    private int limit;
    private String[] fields;
    private DBObject queryObject;
    private DBObject sortObject;

    MongoReader(MongoObjectFactory<DBCollection> collectionFactory) {
        this.collectionFactory = collectionFactory;
    }

    public MongoReader skip(int skip) {
        this.skip = skip;
        return this;
    }

    public MongoReader limit(int limit) {
        this.limit = limit;
        return this;
    }

    public MongoReader select(String[] fields) {
        this.fields = fields;
        return this;
    }

    public MongoReader find(DBObject queryObject) {
        this.queryObject = queryObject;
        return this;
    }

    public MongoReader sort(DBObject sortObject) {
        this.sortObject = sortObject;
        return this;
    }

    private DBCursor getCursor() {
        DBCollection collection = collectionFactory.get();
        assertNotNull(queryObject, "findQuery == null");
        DBCursor cursor;
        if (fields != null) {
            BasicDBObject selectFields = new BasicDBObject();
            for (String field : fields) {
                selectFields.append(field, 1);
            }
            cursor = collection.find(queryObject, selectFields);
        } else {
            cursor = collection.find(queryObject);
        }
        if (skip > 0)
            cursor.skip(skip);
        if (limit > 0)
            cursor.limit(limit);
        if (sortObject != null)
            cursor.sort(sortObject);
        return cursor;
    }

    @Deprecated
    public List<DBObject> query() {
        return execute();
    }

    public List distinct(String key) {
        if (queryObject == null)
            return collectionFactory.get().distinct(key);
        return collectionFactory.get().distinct(key, queryObject);
    }

    /** use {@link #execute(DBObjectEncoder)}*/
    @Deprecated
    public <T> T query(DBObjectEncoder<T> encoder) {
        return execute(encoder);
    }

    public List<DBObject> execute() {
        DBCursor cursor = getCursor();
        List<DBObject> result = new LinkedList<DBObject>();
        while (cursor.hasNext()) {
            result.add(cursor.next());
        }
        cursor.close();
        return result;
    }

    public <T> T execute(DBObjectEncoder<T> encoder) {
        DBCursor cursor = getCursor();
        try {
            assertNotNull(encoder, "encoder == null");
            return encoder.encode(cursor);
        } finally {
            cursor.close();
        }
    }
}