Knoldus

PureConfig has its own predefined behavior for reading and writing to the configuration files, but sometimes we got the tricky requirement in which we need some specific behavior; for example to read the config.

It is possible to override the behavior of PureConfig for a certain type by implementing another instance of ConfigReader, ConfigWriter or ConfigConvert. So in this blog we will discuss all 3 override types.

1. ConfigReader:
The default behavior of PureConfig for String is to return the string itself in the configuration.
For example, when below configuration will be read by PureConfig, it will be read as it is :
application.conf:

company {
  full-name = "Knoldus Software LLP"
  started = 2012
  employees = "80-120"
  offices = ["India", "Singapore", "US", "Canada"]
  offices-in-india {
    head-office = "Delhi"
    development = "Noida"
  }
}

Reading configuration:

import pureconfig.error.ConfigReaderFailures
import pureconfig.loadConfig

class SimpleConfig {
  def getConfig: Either[ConfigReaderFailures, Company] = loadConfig[Company]
}

case class Company(company: CompanyDetails)

case class CompanyDetails(fullName: String,
                          started: Int,
                          employees: String,
                          offices: List[String],
                          officesInIndia: Map[String, String],
                          extraActivity: Option[String])


// Calling and displaying the configuration
val simpleConfig = new SimpleConfig().getConfig

  simpleConfig match {
    case Left(ex) => ex.toList.foreach(println)

    case Right(config) => 
      println(s"Company's Name ${config.company.fullName}")
      println(s"Company started at ${config.company.started}")
      println(s"Company's strength is ${config.company.employees}")
      println(s"Company's presence are in  ${config.company.offices}")
      println(s"Company's office in India are  ${config.company.officesInIndia}")
      println(s"Company's extra activity is  ${config.company.extraActivity}")
  }

Output :

Knoldus Software LLP
2012
80-120
List(India, Singapore, US, Canada)
Map(development -> Noida, head-office -> Delhi)

This is the default behavior of ConfigReader in which the output is same as it is defined in configuration file.

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