Making Your Rails Console Interesting..

As a Rails developer, every time we work on a Rails project we heavily use rails console for development. I love the rails console as much as any Rails developer. It is the best place to experiment or validate your logic but...!

There are some of my personal nit-picks:

• When we are playing around with multiple rails projects and end up opening rails console for multiple projects, then it becomes difficult to identify which rails console belong to which project.
• Another problem with these plain rails console is identifying the rails environment in which we are. Until you run Rails.env you can't be sure.
• But the biggest issue with the plain old rails console is; it is BORING! It's the same old screen every time I open.

Your rails console should be more declartive

Enter the Dotfiles

A little while ago I came to know about dotfiles by Rails conf talk by @bradurani. So basically the dotfiles are the configuration for Unix-y systems. In our daily dev life we use .bashrc, .bash_profile etc.
To my surprise ruby's IRB also has dotfile based configuration .irbrc and rails console is based on IRB so this config does apply to rails console too.

In this blog post, we will explore .irbrc prompt configuration and tackle the issues mentioned above.

IRB provides many prompt modes out of the box, these are NULL, DEFAULT, CLASSIC, SIMPLE, etc.
To switch between these prompt-modes, edit your .irbrc (located in HOME directory, if it's not present, create it.)

	# .irbrc
	IRB.conf[:PROMPT_MODE] = :SIMPLE # default is :DEFAULT
	# Or, invoke irb with the prompt mode by
	# terminal
	❱ irb --prompt simple

view raw irb_command.rb hosted with ❤ by GitHub

There's a lot we need to understand before the above configuration starts making sense.

1 . Specific format for the irb prompt is used:

	{
	PROMPT_I => "" # Simple prompt
	PROMPT_S => "" # Prompt for continued strings
	PROMPT_C => "" # Prompt for continued statement
	RETURN => "" # Format to return value
	}

view raw irbrc prompt options.rb hosted with ❤ by GitHub

2 . Special strings are provided in irb as prompt-helpers:

	%N # command name which is running
	%m # to_s of main object (self)
	%l # type of string(", ', /, ]), `]' is inner %w[...]
	%NNi # indent level. NN is digits and means as same as printf("%NNd").
	%NNn # line number.

view raw irbrc_conf.rb hosted with ❤ by GitHub

Now, let's take a look at how IRB defines Classic mode & Simple mode.

	# IRB Classic prompt
	IRB.conf[:PROMPT_MODE][:CLASSIC] = {
	:PROMPT_I => "%N(%m):%03n:%i> ", # irb(main):001:0>
	:PROMPT_S => "%N(%m):%03n:%i%l ", # irb(main):003:0"
	:PROMPT_C => "%N(%m):%03n:%i* ", # irb(main):005:0*
	:RETURN => "%s\n" # used to printf #
	}
	vs
	# IRB Simple prompt
	IRB.conf[:PROMPT_MODE][:CLASSIC] = {
	:PROMPT_I => ">> ", # >>
	:PROMPT_C => "?> ", # ?>
	:RETURN: => "%s"
	}

view raw irbrc.rb hosted with ❤ by GitHub

Hurray!!, we completed the basic guide, now lets start tweaking with our .irbrc

Let's target our first issue, "How to inform the developer about the rails application name in the rails console?"

The first step, get the application name in rails.

We can find our rails app name in config/application.rb

Note: We will be using meetup rails app for examples

# config/application.rb

module Meetup
  class Application < Rails::Application
  ....
  end
end

Notice that our application name is the module name for rails application class, now let's get it programmatically.

	# We can get application class by
	>> Rails.application.class.name
	# => "Meetup::Application"
	## Since we are only interested in application name, we can get it by
	>> Rails.application.class.module_parent.name
	# => "Meetup"
	# Caveat: In previous versions of ruby, rails it can be acheived by
	>> Rails.application.class.parent.name
	# => "Meetup"

view raw rails application name.rb hosted with ❤ by GitHub

Now let's tackle the second issue, Rails environment information in rails console this is straightforward...

	# We can get rails environment by simply calling
	>> Rails.env
	# => "development"

view raw ralis_environment.rb hosted with ❤ by GitHub

Now let's glue these together with .irbrc

	def application_name
	Rails.application.class.module_parent.name
	end
	def rails_environment
	Rails.env
	end
	# Checking if we are in rails console
	if defined?(Rails)
	prompt = "#{application_name}[#{rails_environment}]"
	# defining custom prompt
	IRB.conf[:PROMPT][:RAILS] = {
	:PROMPT_I => "#{prompt}>> ",
	:PROMPT_N => "#{prompt}> ",
	:PROMPT_S => "#{prompt}* ",
	:PROMPT_C => "#{prompt}? ",
	:RETURN => " => %s\n"
	}
	# Setting our custom prompt as prompt mode
	IRB.conf[:PROMPT_MODE] = :RAILS
	end

view raw irbrc_with_rails_info.rb hosted with ❤ by GitHub

Oh! Wait we still haven't solved the important issue. Its still BOORING plain rails console.
Since irbrc is just ruby, your imagination is only the limitation for making it interesting. Following are my version of rails console's

1. Colorful rails console using Rainbow gem or ANSI escape codes

   	# This gem needs to installed
   	require 'rainbow'
   	def app_prompt
   	rails_klass = Rails.application.class
   	app_name =
   	if rails_klass.respond_to? :module_parent
   	rails_klass.module_parent
   	else
   	rails_klass.parent
   	end
   	Rainbow("#{app_name.name}").blue
   	end
   	# target log path for irb history
   	def log_path
   	rails_root = Rails.root
   	"#{rails_root}/log/.irb-save-history"
   	end
   	def env_prompt
   	case Rails.env
   	when "development"
   	Rainbow("development").green
   	when "production"
   	Rainbow("production").red
   	else
   	Rainbow("#{Rails.env}").yellow
   	end
   	end
   	if defined?(Rails)
   	IRB.conf[:HISTORY_FILE] = FileUtils.touch(log_path).join
   	IRB.conf[:PROMPT] ||= {}
   	prompt = "#{app_prompt}[#{env_prompt}]:%03n "
   	IRB.conf[:PROMPT][:RAILS] = {
   	:PROMPT_I => "#{prompt}>> ",
   	:PROMPT_N => "#{prompt}> ",
   	:PROMPT_S => "#{prompt}* ",
   	:PROMPT_C => "#{prompt}? ",
   	:RETURN => " => %s\n"
   	}
   	IRB.conf[:PROMPT_MODE] = :RAILS
   	end

   view raw irbrc.rb hosted with ❤ by GitHub
   
2. Rails console with emojis

   	# This gem needs to installed
   	require 'rainbow'
   	def app_prompt
   	rails_klass = Rails.application.class
   	app_name =
   	if rails_klass.respond_to? :module_parent
   	rails_klass.module_parent
   	else
   	rails_klass.parent
   	end
   	Rainbow("#{app_name.name}").blue
   	end
   	# target log path for irb history
   	def log_path
   	rails_root = Rails.root
   	"#{rails_root}/log/.irb-save-history"
   	end
   	def env_prompt
   	case Rails.env
   	when "development"
   	Rainbow("development").green
   	when "production"
   	Rainbow("production").red
   	else
   	Rainbow("#{Rails.env}").yellow
   	end
   	end
   	if defined?(Rails)
   	IRB.conf[:HISTORY_FILE] = FileUtils.touch(log_path).join
   	IRB.conf[:PROMPT] ||= {}
   	prompt = "#{app_prompt}[#{env_prompt}]:%03n "
   	IRB.conf[:PROMPT][:RAILS_EMOJI] = {
   	:PROMPT_I => "#{prompt}\u{1F601} >",
   	:PROMPT_N => "#{prompt}\u{1F609} >",
   	:PROMPT_S => "#{prompt}\u{1F606} >",
   	:PROMPT_C => "#{prompt}\u{1F605} >",
   	:RETURN => " => %s\n"
   	}
   	IRB.conf[:PROMPT_MODE] = :RAILS_EMOJI
   	end

   view raw emoji_irbrc.rb hosted with ❤ by GitHub
   

Thank you for reading!!

Comments

[Justin Butkowski]

What font are you using for the emoji icons?

[Akshay Birajdar]

I am using fonts pulled by oh-my-zsh & powerline.

[Nick Taylor]

Nice. I’m still a Ruby newb so this looks pretty cool. Also, congrats on your first post!

[Akshay Birajdar]

Thank you! Nick.

[Kiran Mahale]

Nice one. I was unknown about the dotfiles for IRB. Great!