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play-currency-converter-module

This is a play module for currency conversion. The current version (1.1.5) is compatible with play-2.2. For compatibility with play version 2.1.x use the module version 1.1.4.

Currently, the module is using the Get Exchange Rates service to made the conversion.

Configuring

The first step is include the currency converter in your dependencies list, in Build.scala file:

import sbt._
import Keys._
import play.Project._

object ApplicationBuild extends Build {

  val appName         = "currency-converter-sample"
  val appVersion      = "1.0-SNAPSHOT"

  val appDependencies = Seq(
    // Add your project dependencies here,
    javaCore,
    javaJdbc,
    javaEbean,
    "com.edulify" % "currency-converter_2.10" % "1.1.6"
  )

  val main = play.Project(appName, appVersion, appDependencies).settings(
    // Add your own project settings here
    resolvers += Resolver.url("Edulify Repository", url("http://edulify.github.io/modules/releases/"))(Resolver.ivyStylePatterns)
  )

}

Don't forget to add the resolver to your list of resolvers, or it won't work!

Caching

This module saves a cache of the request made for the service. The default cache time to live is 60 seconds, but this time can be changed using the method setCacheTime(long seconds).

Also, you can set cache off, by calling the method useCache(false). Warning: by setting off the cache, you can overload your system (and the service) due to multiple requests. Without cache activated, every call to Converter.convert will make a request to the choosen web service.

Caching auto-update job (optional)

In order to keep your cache always updated, you can create a background job to auto-update in frequent intervals (based on time to live of the cache). To do this, there are three simple steps to follow:

  • Start the job inside the Global class:
import play.Application;
import play.GlobalSettings;

import com.edulify.modules.currency.ConverterCacheJob;

@SuppressWarnings({ "unchecked", "rawtypes" })
public class Global extends GlobalSettings {

  @Override
  public void onStart(Application app) {
   ConverterCacheJob.startConverterCacheUpdate();
  }
}
  • Set up your Global class in your application.conf:
# Global object class
# ~~~~~
# Define the Global object class for this application.
# Default to Global in the root package.
application.global=Global
  • Set the name for the dispatcher that will do this job (also in the application.conf file):
converter.dispatcher.name = "converter"

Precision

By default, the module makes operations using a precision of 100 decimals. You can change this value using the method setPrecision(int precision). Warning: Low precisions can result in wrong conversions. Change it carefully.

Global configurations

These configurations (about caching and precision) can also be setted globally in the application.conf file, using the following keys:

converter {
  cacheTTL  = 600
  useCache  = true
  precision = 100
}

or

converter.cacheTTL  = 10
converter.useCache  = true
converter.precision = 100

Using

To use this module, its enough to import it in your class and use the static method Converter.convert:

import com.edulify.modules.currency.Converter;

public class Application {
  public static Result index() {
    ...
    try {
      BigDecimal convertedValue = Converter.convert(new BigDecimal(199.0), "EUR", "USD");
    } catch (InvalidCurrencyException ex) {
      ...
    } catch (CommunicationErrorException ex) {
      ...
    }
    ...
  }
}

This method, as shown in the example, should raise two exceptions:

  • InvalidCurrencyException: thrown when the currency code is not valid for the service.
  • CommuncationErrorException: thrown when the service returns an invalid json.
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