Need to access Heroku Postgres DB of a JRuby on Rails app in Java

Question

I need access to the Postgres DB in Java within my JRuby on Rails App. Is this allowed/done. Has anyone done it?

So could I just make a singleton connection to the db via jdbc and manipulate the postgres db?

If so, please can you point me to some resources/examples that may help me this.

I have to build a feature where the Postgres DB records need to be manipulated using a Java API.

Answer 1

Yes, you can do this with the Java APIs in Ruby. It's difficult to provide an exact answer because I do not know what you are trying to do. But here is an example of a method that creates a connection, and manipulates the database in pseudo-JRuby

require 'java'

java_import java.net.URI
java_import java.sql.DriverManager

def do_database
  connection = get_connection

  stmt = connection.createStatement
  stmt.executeUpdate("CREATE TABLE IF NOT EXISTS ticks (tick timestamp)")
  stmt.executeUpdate("INSERT INTO ticks VALUES (now())")
  rs = stmt.executeQuery("SELECT tick FROM ticks")

  rs.next 
  begin
    puts "Read from DB: " + rs.getTimestamp("tick")
  end while rs.next

ensure
  connection.close if connection != nil
end

def get_connection
  dbUri = ENV["DATABASE_URL"]

  username = dbUri.getUserInfo.split(":")[0]
  password = dbUri.getUserInfo.split(":")[1]
  port = dbUri.getPort

  dbUrl = "jdbc:postgresql://#{dbUri.getHost}:#{port}#{dbUri.getPath}"

  DriverManager.getConnection(dbUrl, username, password)
end