byebug_advanced_mastery

🐞 Advanced Byebug Mastery

Byebug is more than just binding.byebug—you can define conditional breakpoints, navigate frames, and even create custom commands in your .byebugrc. This tip shows how to set up complex logic, manipulate variables at runtime, and script byebug to automate repetitive debugging tasks.

# Place this in .byebugrc in your home directory
# Set breakpoint at UsersController#index only if current_user.admin?
break app/controllers/users_controller.rb:10 if current_user&.admin?

# Define a custom command to print relevant request info
defcmd req_info
environment[:request]&.inspect
end

# Automatically list local variables when hitting a breakpoint
display local_variables

Then in your controller:

def index
  binding.byebug
  @users = User.all
end

Run the server, hit the route, and byebug will trigger with your scripted commands. Use up/down to move frames, eval to modify state, and restart to replay your session logic.