mongo_test

mongo_test.java

import com.mongodb.*;

import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Main {

    static final String DELIMITER = "---------------\n";

    public static void main(String[] args) throws UnknownHostException {
        // http://mongodb.github.io/mongo-java-driver/

        MongoClient mongoClient = new MongoClient();
        DB db = mongoClient.getDB("test-ats-db");
        DBCollection products = db.getCollection("products");

        // Clean up the collection.
        products.drop();

        // Create an object and insert it into the collection.
        BasicDBObject potato = new BasicDBObject("name", "potato")
                .append("price", 300)
                .append("type", "potato");
        products.insert(potato);

        // Find the object we've already created.
        DBObject doc = products.findOne();
        System.out.println(doc);
        // -> { "_id" : { "$oid" : "5551b53644ae5de7dde67ae6"} , "name" : "potato" , "price" : 300 , "type" : "potato"}

        // Bulk insert.
        List<DBObject> productsToInsert = new ArrayList<DBObject>();
        productsToInsert.add(
                new BasicDBObject("name", "raspberry").append("price", 400).append("type", "fruit")
        );
        productsToInsert.add(
                new BasicDBObject("name", "caviar").append("price", 1000).append("type", "fish")
        );
        productsToInsert.add(
                new BasicDBObject("name", "apple").append("price", 150).append("type", "fruit")
        );
        productsToInsert.add(
                new BasicDBObject("name", "orange").append("price", 890).append("type", "fruit")
        );
        products.insert(productsToInsert);

        // Search them all.
        System.out.println(DELIMITER + "Search them all:");
        DBCursor allProductsCursor = products.find();
        for (DBObject product : allProductsCursor) {
            System.out.println(product);
        }
        allProductsCursor.close();
        // -> { "_id" : { "$oid" : "5551b53644ae5de7dde67ae6"} , "name" : "potato" , "price" : 300 , "type" : "potato"}
        //    { "_id" : { "$oid" : "5551b53644ae5de7dde67ae7"} , "name" : "raspberry" , "price" : 400 , "type" : "fruit"}
        //    { "_id" : { "$oid" : "5551b53644ae5de7dde67ae8"} , "name" : "caviar" , "price" : 1000 , "type" : "fish"}
        //    { "_id" : { "$oid" : "5551b53644ae5de7dde67ae9"} , "name" : "apple" , "price" : 150 , "type" : "fruit"}
        //    { "_id" : { "$oid" : "5551b53644ae5de7dde67aea"} , "name" : "orange" , "price" : 890 , "type" : "fruit"}

        // Count.
        System.out.println(DELIMITER + "Count:");
        System.out.println(products.count());
        // -> 5

        // Query for potato.
        System.out.println(DELIMITER + "Query for potato:");
        DBObject potatoQuery = new BasicDBObject("name", "potato");

        DBCursor potatoCursor = products.find(potatoQuery);
        for (DBObject product : potatoCursor) {
            System.out.println(product);
        }
        potatoCursor.close();
        // -> "_id" : { "$oid" : "5551b53644ae5de7dde67ae6"} , "name" : "potato" , "price" : 300 , "type" : "potato"}

        // Query for products cheaper than 500.
        System.out.println(DELIMITER + "Query for products cheaper than 500:");
        DBObject cheaperThan500Query = new BasicDBObject("price", new BasicDBObject("$lt", 500));

        DBCursor cheaperThan500Cursor = products.find(cheaperThan500Query);
        for (DBObject product : cheaperThan500Cursor) {
            System.out.println(product);
        }
        cheaperThan500Cursor.close();
        // -> { "_id" : { "$oid" : "5551b53644ae5de7dde67ae6"} , "name" : "potato" , "price" : 300 , "type" : "potato"}
        //    { "_id" : { "$oid" : "5551b53644ae5de7dde67ae7"} , "name" : "raspberry" , "price" : 400 , "type" : "fruit"}
        //    { "_id" : { "$oid" : "5551b53644ae5de7dde67ae9"} , "name" : "apple" , "price" : 150 , "type" : "fruit"}

        // In the same way, we can remove objects that match a query using:
        System.out.println(DELIMITER + "Remove cheaper than 500.");
        products.remove(cheaperThan500Query);

        System.out.println("... and then query all products.");
        allProductsCursor = products.find();
        for (DBObject product : allProductsCursor) {
            System.out.println(product);
        }
        allProductsCursor.close();
        // -> { "_id" : { "$oid" : "5551b53644ae5de7dde67ae8"} , "name" : "caviar" , "price" : 1000 , "type" : "fish"}
        //    { "_id" : { "$oid" : "5551b53644ae5de7dde67aea"} , "name" : "orange" , "price" : 890 , "type" : "fruit"}

        // Clean the db and insert the products again.
        System.out.println(DELIMITER + "Clean the db and insert the products again.");
        products.drop();
        products.insert(potato);
        products.insert(productsToInsert);

        allProductsCursor = products.find();
        for (DBObject product : allProductsCursor) {
            System.out.println(product);
        }
        allProductsCursor.close();
        // -> { "_id" : { "$oid" : "5551b53644ae5de7dde67ae6"} , "name" : "potato" , "price" : 300 , "type" : "potato"}
        //    { "_id" : { "$oid" : "5551b53644ae5de7dde67ae7"} , "name" : "raspberry" , "price" : 400 , "type" : "fruit"}
        //    { "_id" : { "$oid" : "5551b53644ae5de7dde67ae8"} , "name" : "caviar" , "price" : 1000 , "type" : "fish"}
        //    { "_id" : { "$oid" : "5551b53644ae5de7dde67ae9"} , "name" : "apple" , "price" : 150 , "type" : "fruit"}
        //    { "_id" : { "$oid" : "5551b53644ae5de7dde67aea"} , "name" : "orange" , "price" : 890 , "type" : "fruit"}


        // Group by: get the minimum price for every type.
        System.out.println(DELIMITER + "Group by: get the minimum price for every type.");

        List<DBObject> minPricePerTypePipeline = buildListOutOfDBObjects(
                new BasicDBObject("$group",
                        new BasicDBObject("_id", "$type")
                                .append("minimum", new BasicDBObject("$min", "$price"))
                )
        );

        AggregationOutput minPricePerTypeOutput = products.aggregate(minPricePerTypePipeline);
        for (DBObject result : minPricePerTypeOutput.results()) {
            System.out.println(result);
        }
        // -> { "_id" : "fish" , "minimum" : 1000}
        //    { "_id" : "fruit" , "minimum" : 150}
        //    { "_id" : "potato" , "minimum" : 300}


        // Filter price > 500 and then group by minimum price per type.
        System.out.println(DELIMITER + "Filter price > 500 and then group by minimum price per type.");

        List<DBObject> moreThan500PriceAndMinPricePerTypePipeline = buildListOutOfDBObjects(
                new BasicDBObject("$match",
                        new BasicDBObject("price", new BasicDBObject("$gt", 500))
                ),
                new BasicDBObject("$group",
                        new BasicDBObject("_id", "$type")
                                .append("minimum", new BasicDBObject("$min", "$price"))
                )
        );

        AggregationOutput moreThan500PriceAndMinPricePerTypeOutput = products.aggregate(moreThan500PriceAndMinPricePerTypePipeline);
        for (DBObject result : moreThan500PriceAndMinPricePerTypeOutput.results()) {
            System.out.println(result);
        }
        // -> { "_id" : "fruit" , "minimum" : 890}
        //    { "_id" : "fish" , "minimum" : 1000}

        mongoClient.close();
    }

    private static List<DBObject> buildListOutOfDBObjects(BasicDBObject... basicDBObjects) {
        ArrayList<DBObject> dbObjects = new ArrayList<DBObject>();
        Collections.addAll(dbObjects, basicDBObjects);

        return dbObjects;
    }
}