com.examples.aggregation.AggregationExample.java Source code

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Here is the source code for com.examples.aggregation.AggregationExample.java

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/*
 * ${file_name}
 * 
 * Copyright (c) 2013, Jai Hirsch. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301  USA
 */

package com.examples.aggregation;

import java.util.Iterator;

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

public class AggregationExample {
    private DBCollection col;

    public void setCollection(DBCollection col) {
        this.col = col;
    }

    public Iterator<DBObject> simpleAggregation() {
        BasicDBObjectBuilder builder = new BasicDBObjectBuilder();
        builder.push("$group");
        builder.add("_id", "$manufacturer");
        builder.push("num_products");
        builder.add("$sum", 1);
        builder.pop();
        builder.pop();

        return col.aggregate(builder.get()).results().iterator();
    }

    public Iterator<DBObject> compoundAggregation() {
        BasicDBObjectBuilder builder = new BasicDBObjectBuilder();
        builder.push("$group");
        builder.push("_id");
        builder.add("manufacturer", "$manufacturer");
        builder.add("category", "$category");
        builder.pop();
        builder.push("num_products");
        builder.add("$sum", 1);
        builder.pop();
        builder.pop();

        return col.aggregate(builder.get()).results().iterator();
    }

    public Iterator<DBObject> sumPrices() {
        BasicDBObjectBuilder builder = new BasicDBObjectBuilder();
        builder.push("$group");
        builder.add("_id", "$manufacturer");
        builder.push("sum_prices");
        builder.add("$sum", "$price");
        builder.pop();
        builder.pop();

        return col.aggregate(builder.get()).results().iterator();
    }

    public Iterator<DBObject> averagePrices() {
        BasicDBObjectBuilder builder = new BasicDBObjectBuilder();
        builder.push("$group");
        builder.add("_id", "$category");
        builder.push("sum_prices");
        builder.add("$avg", "$price");
        builder.pop();
        builder.pop();

        return col.aggregate(builder.get()).results().iterator();
    }

    public Iterator<DBObject> addToSet() {
        BasicDBObjectBuilder builder = new BasicDBObjectBuilder();
        builder.push("$group");
        builder.push("_id");
        builder.add("maker", "$manufacturer");
        builder.pop();
        builder.push("categories");
        builder.add("$addToSet", "$category");
        builder.pop();
        builder.pop();

        return col.aggregate(builder.get()).results().iterator();
    }

    public Iterator<DBObject> push() {
        BasicDBObjectBuilder builder = new BasicDBObjectBuilder();
        builder.push("$group");
        builder.push("_id");
        builder.add("maker", "$manufacturer");
        builder.pop();
        builder.push("categories");
        builder.add("$push", "$category");
        builder.pop();
        builder.pop();

        return col.aggregate(builder.get()).results().iterator();
    }

    public Iterator<DBObject> maxPrice() {
        BasicDBObjectBuilder builder = new BasicDBObjectBuilder();
        builder.push("$group");
        builder.push("_id");
        builder.add("maker", "$manufacturer");
        builder.pop();
        builder.push("maxprice");
        builder.add("$max", "$price");
        builder.pop();
        builder.pop();

        return col.aggregate(builder.get()).results().iterator();
    }

    public Iterator<DBObject> doubleGroupStages() {
        BasicDBObjectBuilder group_1 = new BasicDBObjectBuilder();
        group_1.push("$group");
        group_1.push("_id");
        group_1.add("class_id", "$class_id");
        group_1.add("student_id", "$student_id");
        group_1.pop();
        group_1.push("average");
        group_1.add("$avg", "$score");
        group_1.pop();
        group_1.pop();

        BasicDBObjectBuilder group_2 = new BasicDBObjectBuilder();
        group_2.push("$group");
        group_2.add("_id", "$_id.class_id");
        group_2.push("average");
        group_2.add("$avg", "$average");
        group_2.pop();
        group_2.pop();

        return col.aggregate(group_1.get(), group_2.get()).results().iterator();
    }

    public Iterator<DBObject> project() {
        BasicDBObjectBuilder builder = new BasicDBObjectBuilder();
        builder.push("$project");
        builder.add("_id", 0);
        builder.push("maker");
        builder.add("$toLower", "$manufacturer");
        builder.pop();
        builder.push("details");
        builder.add("category", "$category");
        builder.push("price");
        builder.add("$multiply", new Object[] { "$price", 10 });
        builder.pop();
        builder.pop();
        builder.add("item", "$name");
        builder.pop();

        return col.aggregate(builder.get()).results().iterator();
    }

    public Iterator<DBObject> match() {
        BasicDBObjectBuilder match = buildMatchDBObject();
        BasicDBObjectBuilder group = new BasicDBObjectBuilder();
        group.push("$group");
        group.add("_id", "$city");
        group.push("population");
        group.add("$sum", "$pop");
        group.pop();
        group.push("zip_codes");
        group.add("$addToSet", "$_id");
        group.pop();
        group.pop();

        return col.aggregate(match.get(), group.get()).results().iterator();
    }

    public Iterator<DBObject> sort() {
        BasicDBObjectBuilder match = buildMatchDBObject();

        BasicDBObjectBuilder group = new BasicDBObjectBuilder();
        group.push("$group");
        group.add("_id", "$city");
        group.push("population");
        group.add("$sum", "$pop");
        group.pop();
        group.pop();

        BasicDBObjectBuilder project = new BasicDBObjectBuilder();
        project.push("$project");
        project.add("_id", 0);
        project.add("city", "$_id");
        project.add("population", 1);
        project.pop();

        BasicDBObjectBuilder sort = new BasicDBObjectBuilder();
        sort.push("$sort");
        sort.add("population", -1);
        sort.pop();

        return col.aggregate(match.get(), group.get(), project.get(), sort.get()).results().iterator();
    }

    public Iterator<DBObject> limitAndSkip() {
        BasicDBObjectBuilder match = buildMatchDBObject();

        BasicDBObjectBuilder group = new BasicDBObjectBuilder();
        group.push("$group");
        group.add("_id", "$city");
        group.push("population");
        group.add("$sum", "$pop");
        group.pop();
        group.pop();

        BasicDBObjectBuilder project = new BasicDBObjectBuilder();
        project.push("$project");
        project.add("_id", 0);
        project.add("city", "$_id");
        project.add("population", 1);
        project.pop();

        BasicDBObjectBuilder sort = new BasicDBObjectBuilder();
        sort.push("$sort");
        sort.add("population", -1);
        sort.pop();

        BasicDBObject skip = new BasicDBObject("$skip", 10);
        BasicDBObject limit = new BasicDBObject("$limit", 5);

        return col.aggregate(match.get(), group.get(), project.get(), sort.get(), skip, limit).results().iterator();
    }

    private BasicDBObjectBuilder buildMatchDBObject() {
        BasicDBObjectBuilder match = new BasicDBObjectBuilder();
        match.push("$match");
        match.add("state", "NY");
        match.pop();
        return match;
    }

    public Iterator<DBObject> unwind() {
        BasicDBObject unwind = new BasicDBObject("$unwind", "$tags");

        BasicDBObjectBuilder group = new BasicDBObjectBuilder();
        group.push("$group");
        group.add("_id", "$tags");
        group.push("count");
        group.add("$sum", 1);
        group.pop();
        group.pop();

        BasicDBObjectBuilder sort = new BasicDBObjectBuilder();
        sort.push("$sort");
        sort.add("count", -1);
        sort.pop();

        BasicDBObject limit = new BasicDBObject("$limit", 10);

        BasicDBObjectBuilder project = new BasicDBObjectBuilder();
        project.push("$project");
        project.add("_id", 0);
        project.add("tag", "$_id");
        project.add("count", 1);

        return col.aggregate(unwind, group.get(), sort.get(), limit, project.get()).results().iterator();
    }

    public Iterator<DBObject> doubleUnwind() {

        BasicDBObject unwindSizes = new BasicDBObject("$unwind", "$sizes");
        BasicDBObject unwindColors = new BasicDBObject("$unwind", "$colors");

        BasicDBObjectBuilder group = new BasicDBObjectBuilder();
        group.push("$group");
        group.push("_id");
        group.add("size", "$sizes");
        group.add("color", "$colors");
        group.pop();
        group.push("count");
        group.add("$sum", 1);
        group.pop();
        group.pop();

        return col.aggregate(unwindSizes, unwindColors, group.get()).results().iterator();
    }
}