How to correctly set up Pry in Rails 4.2

Question

I'm confused about which gems need to be installed to correctly run Pry in a Rails 4.2 project. I seemed to be doing fine until recently. For some reason, binding.pry now seems to spit up whenever I try to step through a console session with next, step, etc in the command line. It will throw an ugly stack trace, then show me the same point in the code, without stepping further. After the second next command, it throws the same stack trace and quits, returning execution to the localhost server. I get a runtime error on the browser page with No frames collected.

If I comment out the binding.pry in my code, everything works fine. So I strongly suspect something is wrong with my configuration of Pry. It seems like there are several dozen variations of Pry, with no clear guidance on which one(s) should be installed, which might conflict, etc.

Here's the stack trace I get when calling next in the Pry console after the code reaches the binding.pry call:

From: /Users/me/sites/arailsapp/app/controllers/bars_controller.rb @ line 31 BarsController#edit:

    29: def edit
    30:   binding.pry
 => 31:   @bar = Bar.find(params[:id])
    32:   @foo = @bar.foo
    33: end

[6] pry(#<BarsController>)> n
Completed 500 Internal Server Error in 2685ms (ActiveRecord: 0.0ms)

RuntimeError - No frames collected.:
  pry-byebug (3.2.0) lib/byebug/processors/pry_processor.rb:122:in `perform_next'
  pry-byebug (3.2.0) lib/byebug/processors/pry_processor.rb:60:in `perform'
  pry-byebug (3.2.0) lib/byebug/processors/pry_processor.rb:49:in `run'
  pry-byebug (3.2.0) lib/byebug/processors/pry_processor.rb:111:in `resume_pry'
  pry-byebug (3.2.0) lib/byebug/processors/pry_processor.rb:69:in `at_line'
  byebug (5.0.0) lib/byebug/context.rb:90:in `at_line'
  app/controllers/scholarships_controller.rb:31:in `edit'
  actionpack (4.2.1) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
  actionpack (4.2.1) lib/abstract_controller/base.rb:198:in `process_action'
  actionpack (4.2.1) lib/action_controller/metal/rendering.rb:10:in `process_action'
  actionpack (4.2.1) lib/abstract_controller/callbacks.rb:20:in `block in process_action'
  activesupport (4.2.1) lib/active_support/callbacks.rb:117:in `call'

  # omitting the next ~40 lines in the Rails stack...

Second verse looks same as the first - at which point execution returns to the server.

Here is my Gemfile:

source 'https://rubygems.org'

ruby '2.2.0'

gem 'rails', '4.2.1'
gem 'pg', '~> 0.18.2'
gem 'haml-rails', '~> 0.9.0'
gem 'sass-rails', '~> 5.0'
gem 'jquery-rails'
gem 'turbolinks'
gem 'jbuilder', '~> 2.0'
gem 'sdoc', '~> 0.4.0', group: :doc
gem 'will_paginate', '~> 3.0.7'
gem 'will_paginate-bootstrap'
gem "nilify_blanks"
gem 'filterrific', '~> 2.0.5'
gem 'chardinjs-rails'

# Install bootstrap and associated gems
gem 'bootstrap-sass', '~> 3.3.4.1'
gem 'autoprefixer-rails', '~> 5.2.0'

# Use ActiveModel has_secure_password
gem 'bcrypt', '~> 3.1.7'

group :production do
  gem 'rails_12factor', '~> 0.0.3'
end

group :assets do
  gem 'uglifier', '>= 1.3.0'
  gem 'coffee-rails', '~> 4.1.0'
end

group :development do
  gem 'better_errors', '~> 2.1.1'
  gem 'annotate', '~> 2.6.10'
end

group :development, :test do
  gem 'pry-rails'
  gem 'pry-stack_explorer'      
  gem 'pry-byebug'
  gem 'web-console', '~> 2.0'
  gem 'spring'
  gem 'spring-commands-rspec', '~> 1.0.4'
  gem 'rspec-rails', '~> 3.2.3'
  gem 'guard-rspec', '~> 4.6.0'
  gem 'sqlite3'
  gem 'factory_girl_rails', '~> 4.5.0', require: false
end

group :test do
  gem 'database_cleaner', '~> 1.4.1'
  gem 'faker', '~> 1.4.3'
  gem 'capybara', '~> 2.4.4'
  gem 'launchy', '~> 2.4.3'
  gem 'shoulda', '~> 3.5.0'
end

I've also tried with the pry-stack_explorer and pry-byebug gems commented out...no difference.

And finally, my .pryrc file:

# ~/.pryrc
if defined?(PryByebug)
  Pry.commands.alias_command 'c', 'continue'
  Pry.commands.alias_command 's', 'step'
  Pry.commands.alias_command 'n', 'next'
  Pry.commands.alias_command 'f', 'finish'
end

# Hit Enter to repeat last command
Pry::Commands.command /^$/, "repeat last command" do
  _pry_.run_command Pry.history.to_a.last
end

Tani

I just use pry-rails. Sometimes I've used it with byebug (not pry-byebug). Perhaps start with just one and be sure to bundle when updating. These gems can sometimes throw up rabbit hole errors, so add some logging if you're not convinced by what pry is reporting. – Petronel

First of all, remove pry-stack_explorer from you Gemfile and rebundle. That gem is incompatible with pry-byebug and pry-byebug offers equivalent functionality so it's just not necessary. – Apocrine

@Apocrine sorry, maybe I'm confused, but what's the equivalent functionality to show-stack that pry-byebug offers? I don't see any ability to show the current stack. "pry-backtrace" is close, but it is cluttered up with internal pry methods. – Roca

Hei, you're right. We have commands to move up and down the stack, but not to display it. You can use Ruby for that though, Thread.current.backtrace_locations. – Apocrine

Answer 1

Some fiddling around and a couple of server restarts appear to have fixed the issue. Thanks to Deivid for suggesting remvoving pry-stack_explorer. Here's the Gemfile for the test and development groups:

group :development do
  gem 'better_errors', '~> 2.1.1'
  gem 'annotate', '~> 2.6.10'
end

group :development, :test do
  gem 'pry-rails'
  gem 'pry-byebug'
  gem 'web-console', '~> 2.0'
  gem 'spring'
  gem 'spring-commands-rspec', '~> 1.0.4'
  gem 'rspec-rails', '~> 3.2.3'
  gem 'guard-rspec', '~> 4.6.0'
  gem 'sqlite3'
  gem 'factory_girl_rails', '~> 4.5.0', require: false
end

group :test do
  gem 'database_cleaner', '~> 1.4.1'
  gem 'faker', '~> 1.4.3'
  gem 'capybara', '~> 2.4.4'
  gem 'launchy', '~> 2.4.3'
  gem 'shoulda', '~> 3.5.0'
end

Tani