Use Scala to manipulate MongoDB

Introduced

Scala is a kind of functional object-oriented language . It blends a lot of unprecedented features. At the same time, it executes on top of the JVM . With the growing interest of developers in Scala , and the increasing number of tools to support it, the Scala language will undoubtedly be an indispensable tool in your hands.

MongoDB is a product between a relational database and a non-relational database, which is the most versatile and most like a relational database. The data structure he supports is very loose and is a json - like bson format. It is therefore possible to store more complex data types.

Mongo The biggest feature is that the query language he supports is very powerful, and its syntax is a bit like an object-oriented query language, almost capable of implementing most of the functions of a relational database single-table query, and also supports indexing of data .

in this article. We'll show you how to connect to Mongodb and data processing using the Scala language .

Environment Installation and configuration

First. Install MongoDB and Scala, assuming it's already installed. Be able to skip this step. Detailed installation procedures please search by yourself.

Second. Install SBT. SBT is the build tool in Scala. function equivalent to maven.

Installation is relatively simple, detailed steps please refer to: http://www.scala-sbt.org/0.13/tutorial/zh-cn/Setup.html

Third, after installation is complete. Running the SBT command on the console, a message similar to the following appears:

[Email protected] scala-project]# SBT

[INFO] Loading Global Plugins From/root/.sbt/0.13/plugins

[INFO] Set current project to Casbah Tutorial (in buildfile:/home/apache/src/scala-project/)

>

Four: Create a test item and load it into the Casbah library. Casbah is MongoDB's Scala driver

mkdir Test-project

CD Test-project

VI BUILD.SBT, Input:

Name: = "Casbah Test"

Version: = "1.0"

Scalaversion: = "2.11.2"

Librarydependencies + = "Org.mongodb" percent "Casbah"% "2.7.3"

Note: There is a blank line cut for each line in the BUILD.SBT file.

If you have any questions, please refer to http://mongodb.github.io/casbah/guide/installation.html

After completion of the input command: Sbtconsole, the first time the implementation will voluntarily download the Casbah and other dependent libraries, after loading for example, such as the following information is possible.

Welcome to Scala version 2.11.2 (Java HotSpot (TM) 64-bit Server Vm,java 1.7.0_13).

Type in expressions to has them evaluated.

Type:help for more information.

Scala>

Connect to MongoDB

Loading Scala SHELL:SBT Console

Importcom.mongodb.casbah.imports._

Val mongoclient= mongoclient ("localhost", 27017)

Note: You can enter mongoclient in the console. + SPACEBAR, the system will proactively prompt for available actions.

Multiple connection modes are supported:

1. Simple Way

Connect to Default-localhost, 27017

Val mongoclient = Mongoclient ()

Connect to "MONGODB01" host, default port

Val mongoclient = mongoclient ("Mongodb01")

Connect to "MONGODB02" host, Port 42017

Val mongoclient = mongoclient ("mongodb02", 42017)

2. Uri method

Val uri = Mongoclienturi ("mongodb://localhost:27017/")

Val mongoclient = mongoclient (URI)

3. Support Authorization method

Challenge Response

Valserver = new ServerAddress ("localhost", 27017)

Valcredentials = Mongocredential.createmongocrcredential (UserName, Database,password)

Valmongoclient = mongoclient (server, List (credentials))

X.509protocol

Valserver = new ServerAddress ("localhost", 27017)

Valcredentials = mongocredential.createmongox509credential (userName)

Valmongoclient = mongoclient (server, List (credentials))

...

Many other connection information, please refer to: http://mongodb.github.io/casbah/guide/connecting.html

We create a test_db database and test collection in MongoDB, and choose a simple user password way, such as the following:

Val Server = newserveraddress ("localhost", 27017)

Val Credentials =mongocredential.createmongocrcredential ("User", "test_db", "Pass". ToArray)

Val mongoclient= mongoclient (server, List (credentials))

A connection that appears similar to the following information is successful:

res2:com.mongodb.casbah.MongoClient = [email protected]

Get databases and connections:

Val db = Mongoclient ("test_db")

Db.collectionnames

Val coll = db ("Test")

Adding and removing changes and checking operation

Add to

Val user1 = mongodbobject ("name", "user1")

Val user2 = mongodbobject ("name", "User2")

Coll.insert (User1)

Coll.insert (User2)

Read

Coll.count ()//Read total number of records

You can also use Find to read records, such as reading all records and printing them:

Coll.find (). foreach (println)

Val query1 =mongodbobject ("name", "user1")

Coll.findone (Query1)

Update

Val update1 =mongodbobject ("email", "[email protected]")

Val result1 = coll.update (query1,update1)

println ("number updated:" +RESULT.GETN)

or Val result = coll.update (query, update, upsert=true)//upsert=true, assuming there is no insert

Delete

Val Query2 = mongodbobject ("name", "User2")

Val result2 = Coll.remove (Query2)

Delete Collection

Coll.drop ()

Many other use methods please refer to Casbah user documentation http://mongodb.github.io/casbah/index.html

Copyright notice: This article blog original articles, blogs, without consent, may not be reproduced.

Use Scala to manipulate MongoDB