Show Hibernate parameters with nicely formatted query

Sometime for the debugging it is really handy, to do it, you need:

log4j.properties

log4j.logger.org.hibernate=INFO, hb log4j.logger.org.hibernate.SQL=DEBUG log4j.logger.org.hibernate.type=TRACE log4j.logger.org.hibernate.hql.ast.AST=info log4j.logger.org.hibernate.tool.hbm2ddl=warn log4j.logger.org.hibernate.hql=debug log4j.logger.org.hibernate.cache=info log4j.logger.org.hibernate.jdbc=debug log4j.appender.hb=org.apache.log4j.ConsoleAppender log4j.appender.hb.layout=org.apache.log4j.PatternLayout log4j.appender.hb.layout.ConversionPattern=HibernateLog --> %d{HH:mm:ss} %-5p %c - %m%n log4j.appender.hb.Threshold=TRACE hibernate.cfg.xml <property name="show_sql">true</property> <property name="format_sql">true</property> <property name="use_sql_comments">true</property>

Thanks Tommaso Taruffi, http://stackoverflow.com/questions/2536829/hibernate-show-real-sql

Replication in MongoDB

!!!!!!!!!!!!!!!!!!!!!!!
Replication
!!!!!!!!!!!!!!!!!!!!!!!

cd data
mkdir rs1 rs2 rs3
cd..
mongod --replSet m101 --logpath "1.log" --dbpath /data/rs1 --port 27017 --smallfiles
mongod --replSet m101 --logpath "2.log" --dbpath /data/rs2 --port 27018 --smallfiles

mongod --replSet m101 --logpath "3.log" --dbpath /data/rs3 --port 27019 --smallfiles

this shell script (started from mongo folder) should create replica set of 3 servers on Windows

config = { _id: "rs1" , members: [
{_id:0, host: "<here should be name of your computer> : 27017" , priority:0, slaveDelay:5 } ,
{_id:1, host: "<here should be name of your computer> : 27018"} ,
{_id:1, host: "<here should be name of your computer> : 27019"}]
} 

rs.initiate(config)

this commands will initiate replica set, where server with _id:0 will be hidden member

mongo shell aggregate framework examples

!!!!!!!!!!!!!!!!
Group
!!!!!!!!!!!!!!!!

db.products.aggregate([ {$group: {_id:"$category" , num_products : {$sum:1} }} ])
will return document "result" that have ids of categories that there is in products collection with field num_products with value of number of items of specified category

db.products.aggregate([ {$group: {_id: {"manufacturer" : "$manufacturer" , "category":"$category" } , num_products : {$ sum:1} }} ])
group by compound key example

db.products.aggregate([ {$group: {_id:"$manufacturer" , sum_prices: {$sum:"$price"} }} ])
calculation of sum of totall price of devices of produced by every manufacturer

db.products.aggregate([ {$group: {_id:"$manufacturer" , avg_price: {$avg:"$price"} }} ])
calculation of the average price of devices of produced by every manufacturer

db.products.aggregate([ {$group: {_id:"$manufacturer" , categories: {$push:"$category"} }} ])
getting collection groupped by manufacturer with array (set) of categories where every category as many time in array as many such category of such manufacturer is exists in collection

db.products.aggregate([ {$group: {_id:"$manufacturer" , categories: {$push:"$category"} }} ])
getting collection groupped by manufacturer with array (set) of categories where every category as many time in array as many such category of such manufacturer is exists in collection

db.zips.aggregate([{$group:{_id:"$state","pop": {$max:"$pop"}}}])
The aggregation query that will return the population of the postal code in each state with the highest population.

db.group.aggregate([{
$group:{_id:   { class_id: "$class_id" , student_id :  "$student_id" } , average : {"$avg"  : "$score"}}} ,
{$group: {_id : "$_id.class_id" , average :{ "$avg" : "$average"}}
}])
The two step group example, on the first step we creating collection with unique pairs class_id and student_id evaluate average score for this pairs, on the second step we getting calculatting average score of certain student for certain class

!!!!!!!!!!!!!!!!
Project
!!!!!!!!!!!!!!!!
db.zips.aggregate([{$project:{_id:0, city:{$toLower:"$city"}, pop:1, state:1, zip:"$_id"}}])

projection example:
from such collection:
{
"city" : "ACMAR",
"loc" : [
-86.51557,
33.584132
],
"pop" : 6055,
"state" : "AL",
"_id" : "35004"
}

will return such:
{
"city" : "acmar",
"pop" : 6055,
"state" : "AL",
"zip" : "35004"
}

db.products.aggregate([ {$group: {_id:"$manufacturer" , sum_prices: {$sum:"$price"} }} ])
calculation of sum of totall price of devices of produced by every manufacturer

db.products.aggregate([ {$group: {_id:"$manufacturer" , avg_price: {$avg:"$price"} }} ])
calculation of the average price of devices of produced by every manufacturer


!!!!!!!!!!!!!!!!
Match
!!!!!!!!!!!!!!!!

db.zips.aggregate([{ $match : {state: NY} }])
kind of fillter, will return only documents where state is NY

!!!!!!!!!!!!!!!!!!!!!!!!!!!
Sort, Skip and Limit
!!!!!!!!!!!!!!!!!!!!!!!!!!!

db.zips.aggregate([{ $sort: {state : 1} }  , {$skip:10} , {$limit:5}]) 
query with just a sort stage to sort by state, ascending, skip the first 10 and get only next 5

!!!!!!!!!!!!!!!!
First and Last
!!!!!!!!!!!!!!!!

db.fun.aggregate([{$sort:{c:1}}, {$group:{_id:"$a", c:{$first:"$c"}}}])
will return collection of different "a" and for "c" key for the document from this collection will be the smallest "c" value for the corresponded "a"

!!!!!!!!!!!!!!!!
Unwind
!!!!!!!!!!!!!!!!

db.posts.aggregate([{ $unwind:"$comments"}]) 

from the posts collection will return new collection in which for every array element in comments arrat will be create new document

mongo shell indexes usage + miscellaneous comands

!!!!!!!!!!!!!!!!
Indexes
!!!!!!!!!!!!!!!!

db.students.ensureIndex({class:1, student_name:-1})
adding an index to a collection named students, having the index key be class, student_name.
class: ascending sorted index

student_name: descending sorted index

db.system.indexes.find()
getting all added indexes in the database

db.students.getIndexes()
getting all added indexes in the collection students

db.students.dropIndex({'class':1, 'student_name':-1})
dropping index created by db.students.ensureIndex({class:1, student_name:-1}) command

db.students.ensureIndex({''student_name':-1} , {unique:true})
create index on student_name that is unique (this action, actually, force student_name be unique)

db.students.ensureIndex({''student_name':-1} , {unique:true} , {dropDups:true})
create index on student_name that is unique and delete all duplicates of the same student_name

db.students.ensureIndex({''student_name':-1} , {unique:true} , {sparce:true})
create index on student_name that is unique and only on the documents that has student_name not null

db.scores.totalIndexSize()
getting size of al indexes in the collection scores

db.scores.find({type:"essay" , score:50} ).hint({type: 1})
if in the collection score 2 indexes were added (one on type and one on score), the hint command forces to use index on type

db.scores.find({type:"essay" , score:50}).hint({$natural:1})
forces not tu use index at all

!!!!!!!!!!!!!!!!
Miscellaneous
!!!!!!!!!!!!!!!!

db.scores.find({type:"essay" , score:50}).explain()
getting information how find was actually perfomed

db.scores.stats()
getting collection statistics

db.system.profile.find()
finding logs of the selected DB

db.students.drop()
dropping students collection

db.dropDatabase()
dropping database

mongoimport -d school -c students < students.json
import documents from students.json to the school database to the students collection

hw 3.2 jUnit coverage

//here the example of coverage hw 3.2 + 3.3 by unit tests

import com.mongodb.*;
import course.BlogPostDAO;
import org.junit.After;
import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Test;
import java.net.UnknownHostException;
import java.util.Arrays;
import java.util.List;
import static junit.framework.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

public class BlogPostDAOTest {

    static MongoClient mongoClient;
    static DB blogDatabase;
    static DBCollection blogPostCollection;
    static BlogPostDAO blogPostDAO;

    // this method called before all test (once), to initialize DB variables
    @BeforeClass
    public static void setUp() throws UnknownHostException {
        mongoClient = new MongoClient();
        blogDatabase = mongoClient.getDB("blog");
        blogPostCollection = blogDatabase.getCollection("posts");
        blogPostDAO = new BlogPostDAO(blogDatabase);
        blogPostCollection.drop();
    }

    //this method calls after every test to clean usersCollection
    @After
    public void dropCollection() {
        blogPostCollection.drop();
    }

    @Test
    public void addUserTest() {

        System.out.println("Starting test on adding post");
        String body = "this is body of post";

        blogPostDAO.addPost("hello post", body, Arrays.asList(new String[]{"Awesome tag", "Tag 2", "Tag 3"}), "b1102");

        DBObject find = new BasicDBObject("body", "this is body of post");

        DBObject post = blogPostCollection.find(find).next();

        assertTrue(post.get("body").equals(body));

        System.out.println("Post successfully added");
        System.out.println("");

    }

    @Test
    public void findPostByPermalinkTest() {
        System.out.println("Starting test on finding post by permalink");

        String body = "this is body of post";

        String permalink = blogPostDAO
                .addPost("hello post", body, Arrays.asList(new String[]{"Awesome tag", "Tag 2", "Tag 3"}), "b1102");
        DBObject foundPost = blogPostCollection.findOne();

        assertEquals(foundPost, blogPostDAO.findByPermalink(permalink));

        System.out.println("Test on finding post by permalink successfully finished");
        System.out.println("");

    }

    @Test
    public void addCommentTest() {
        System.out.println("Starting test on adding comment with email");

        String body = "this is body of post";

        String permalink = blogPostDAO.
                addPost("Post number: ", body, Arrays.asList(new String[]{"Awesome tag", "Tag 2", "Tag 3"}), "b1102");

        String theSecondCommentName = "The second comment";
        String theFirstCommentBody = "Comment 1 body";


        blogPostDAO.addPostComment("The first comment", "b1102@pochta.ru", theFirstCommentBody, permalink);
        blogPostDAO.addPostComment(theSecondCommentName, null, "Comment 2 body", permalink);


        DBObject commentedPost = blogPostDAO.findByPermalink(permalink);

        List<BasicDBObject> comments = (List<BasicDBObject>) commentedPost.get("comments");

        assertEquals(comments.size(), 2);

        Assert.assertEquals(comments.get(1).get("author"), theSecondCommentName);


        System.out.println("Test on adding comment with email successfully finished");
        System.out.println("");

    }

    // pretty long tests (takes 20 second), because wait 5 seconds after adding post, to get create posts in different time
    //comment if you don't want to use it and wait so long every build

    @Test
    public void findByDateDescendingTest() throws InterruptedException {
        System.out.println("Starting test on finding posts by date descending");

        String body = "this is body of post";

        for (int i = 1; i < 5; i++) {
            String permalink = blogPostDAO.
                    addPost("Post number: " + i, body, Arrays.asList(new String[]{"Awesome tag", "Tag 2", "Tag 3"}), "b1102");
            //waiting 10 seconds
            System.out.println("Waiting 5 seconds before adding new post");
            Thread.sleep(5000);
        }

        List<DBObject> foundedList = blogPostDAO.findByDateDescending(3);

        assertEquals(3, foundedList.size());

        System.out.println(foundedList.get(1).get("title"));

        assertEquals(foundedList.get(1).get("title"), "Post number: 3");

        System.out.println("Test on finding post by permalink successfully finished");
        System.out.println("");

    }

}

Easy way to insert List of Strings

//if, for example, you have some function that takes List of Strings as parameter
//the easiest way (for me) to test this function is to call it in such way

function (Arrays.asList(new String []{"List element 1", "List element 2", "List element 3"}))

Example of coping file

 //this is example of function that takes root to the folder where target file lies, and copy there file
 //Contracts_Postpaid_80.xls to the file Contracts_For_VVL.xls which will be created
    public void copyContractsForVVL(String folder) {

        InputStream inStream = null;
        OutputStream outStream = null;

        try {

            File fileToCopy = new File(folder + "//Contracts_Postpaid_80.xls");
            File copiedFile = new File(folder + "//Contracts_For_VVL.xls");

            inStream = new FileInputStream(fileToCopy);
            outStream = new FileOutputStream(copiedFile);

            byte[] buffer = new byte[1024];

            int length;
            //copy the file content in bytes
            while ((length = inStream.read(buffer)) > 0) {

                outStream.write(buffer, 0, length);

            }

            inStream.close();
            outStream.close();

            System.out.println("File is copied successful!");

        } catch (IOException e) {
            e.printStackTrace();
        }
    }