Smile

# Mongo Module

# Creating a mongo module

  1. Open Mould.ksmile file, add a mongo module to the project
section learning {
	data-module LearningData at com.metastay.learningdata
	mongo-module LearningMongo at com.metastay.learningmongo
}
  1. Open sbt console and run smile command
mould>sbt
[Mould] $ smile
[info] smile build
[info] updating modules ...
[info] creating module :LearningMongo
[info] reloading ...
...
  1. Refresh the project in eclipse
  2. You will see the LearningMongo.kmongo file created under learning package

# Define Employee collection

  1. Open LearningMongo.kmongo in eclipse
  2. Define Employee collection as follows:
collection Employee {
	property name:String
	property gender:String
	property yearOfJoining:Int
	property designation:String
	property experienceInMonths:Int
	property emailId:String?
}
  1. Make sure compile is successful
  2. Change designation type to enum
    • Since enum is defined in a different module, we need to specify the module dependency in the ksmile file.
    • Open .ksmile file, add data module dependency to mongo module in order to access the DesignationType enum.
section learning {
	data-module LearningData at com.metastay.learningdata
	mongo-module LearningMongo(LearningData) at com.metastay.learningmongo
}
  • Any change to ksmile requires you to run smile command.
[Mould] $ smile
  • Open LearningMongo.kmongo, change designation type from String to LearningData:: DesignationType
collection Employee {
	property name:String
	property gender:String
	property yearOfJoining:Int
	property designation:LearningData:: DesignationType
	property experienceInMonths:Int
	property emailId:String?
}
  • Make sure compile is successful

# Create Company collection

  1. Open LearningMongo.kmongo in eclipse and define Company collection as follows:
collection Company {
	property name:String
	property address:String	
}
  1. Make sure compile is successful
  2. Adding a collection reference (foreign key):
    • Let's link company and employee by adding company's reference to employee:
collection Employee {
	property name:String
	property gender:String
	property yearOfJoining:Int
	property designation:LearningData:: DesignationType
	property experienceInMonths:Int
	property emailId:String?
	**reference company:Company**
}
  • Make sure compile is successful
    • This creates a soft link between Employee & company through the company's _id.
    • This spec creates a company_oid field in employee collection, and provides you the company object which is lazily loaded on access.

# CRUD operations

  1. Smile generates the following classes for every collection defined in kmongo spec.

    • <Collection>Row
    • <Collection>Query
    • <Collection>Writer
    • <Collection>Update
    • <Collection>Reader

  2. Insert/Save a record using CollectionWriter

    • Open LearningMongoObject.scala in intelliJ
    • Define a function to insert a company into database.
object LearningMongoObject extends LearningMongoTrait {
	def createCompany(name:String, address:String): Unit = {
	 val companyRow = CompanyRow(
	   name = name ,
	   address = address
	 )
	 CompanyWriter().insert(companyRow)
	}
}
  • Call this method from a test-case in the mongo module :
class LearningMongoTestSuite extends ... {
	test("create a company", Tag("create")) {
		println("creating a company..")
		createCompany(name = "Software Solutions", address = "HSR, India")
		println("done.")
	}
}
  • Run the test to create a new company in db:
[Mould] $ project LearningMongo
[info] Set current project to LearningMongo (in build file:/Users/<username>/metastay/mould/)
[LearningMongo] testOnly *LearningMongoTestSuite* -- -n create
creating a company..
done.
[info] LearningMongoTestSuite:
[info] - create a company
[info] ScalaTest
...
  • Open mongo viewer & you will see a new row created in company collection

  1. Read record using CollectionQuery

    • define a function to read all companies in database.
object LearningMongoObject extends LearningMongoTrait {
	def listCompanies(): List[CompanyRow] = {
	 CompanyQuery().find
	}
}
  • Call this method from a test-case in the mongo module :
class LearningMongoTestSuite ... {
	test("list all companies", Tag("read")) {
		val companyList = listCompanies()
		println("Company List: " + companyList)
	}
}
  • Run the test case to list all companies:
[LearningMongo] testOnly *LearningMongoTestSuite* -- -n read
...
Company List: List(CompanyRow(_id=5b0291bb77c8344dea90372c,name=Software Solutions,address=HSR, India))
[info] LearningMongoTestSuite:
[info] - list all companies
...
  • Exercise: Write a function to get the details of a company given the company name.

  1. Update a record using CollectionUpdate

    • define a function to update a company's address
object LearningMongoObject extends LearningMongoTrait {
	def updateCompany(name:String, newAddress:String): Unit = {
		val q = CompanyQuery().name.is(name)
		val u = CompanyUpdate().address.set(newAddress)
		CompanyWriter().updateOne(q,u)
	}
	...
}
  • Call this method from a test-case in the mongo module :
class LearningMongoTestSuite ... {
	test("update company address", Tag("update")) {
	 	println("updating company... ")
	 	updateCompany(name = "Software Solutions", newAddress = "Koramangala, India" )
	 	println("done.")
	}
	...
}
  • Run the test case to see the change in db.
[LearningMongo] testOnly *LearningMongoTestSuite* -- -n update
...
  1. Delete a record
  • define a function to remove a given company
object LearningMongoObject extends LearningMongoTrait {
	def removeCompany(name:String): Unit = {
		 val q = CompanyQuery().name.is(name)
		 CompanyWriter().remove(q)
	}
	...
}
  • Call this method from a test-case in the mongo module :
class LearningMongoTestSuite ... {
	test("remove company", Tag("remove")) {
		 println("removing company.. ")
		 removeCompany(name = "Software Solutions")
		 println("done.")
	}
	...
}
  • Run the test case to see the change in db.
		[LearningMongo] testOnly *LearningMongoTestSuite* -- -n remove
  1. Collection extension classes: extend vs object extend

You can add some commonly accessed methods to a collection using an object extend ex: listCompainesInCity(city:String). Where as for instance specific apis use extend, ex: it would be usefull to get a method like getAllEmployeeList defined on a company row.

  • Open file LearningMongo.kmongo in eclipse
  • Add the extend keyword in Company collection definition:
collection Company extend {
	property name:String
	property address:String
}
  • On compile, you must see a file by name CompanyRowExtn created with the company row available in scope
  • Define getAllEmployeeList in this extension class
trait CompanyRowExtn extends CompanyRowExtnTrait {
 row: CompanyRow =>
 def getAllEmployeeList: List[EmployeeRow] = {
   EmployeeQuery().company_oid.is(row._id).find
 }
}
  • Call this api from a test:
class LearningMongoTestSuite ... {
	test("list all employees", Tag("employees")) {
		 val name = "Software Solutions"
		 createCompany(name = name, address = "HSR, India")
		 val company = findCompany(name = name).get
		 val employeeList = company.getAllEmployeeList
		 println("Employee List: " + employeeList)
	}
	...
}
  • Run the test case to see the results.
[LearningMongo] testOnly *LearningMongoTestSuite* -- -n employees

# Assignment

  1. Re-code all the company apis written earlier to read from database as opposed to in-memory.
  2. Copy, modify & run test cases from LearningMongoTestSuite.

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