Helpful Debugging Tips for Ruby on Rails

catching_errors.rb

class ApplicationController < ActionController::Base
    def log_error error_message
        # Defining our log file path, can be named or located anywhere. 
        log_file_path = "#{Rails.root}/log/exception.log"
        
        # Check if our log file exists.
        file_available = File.exist? log_file_path
        
        # Create log file if not available.
        if file_available == false
            Logger.new(log_file_path)
        end

        # Open and append our error message to log file.
        # NOTE: "a" stands for append mode
        File.open(log_file_path, "a") do |f| 
           f.puts Time.now
           f.puts error_message 
        end
    end
  
end

class ItemsController
    def show
        # Instance variables will return nil regardless even when undeclared, just demonstrating what to expect
        # when an item is not found.
        @item = nil
     
        begin
            # When item is not nil, it will throw an internal server error unless be wrap this find in a b/r/e(begin, rescue, end).
            # Internal server error is not attractive to users and often when they see errors, they can stop using the product entirely.
            @item = Item.find(params[:id])

        rescue Exception => exception
            # Log expection.
            # It's important to log enough data to reproduce a problem. 
            # Also be warned if any of the variables like params or current_user is not available, nothing will be logged
            # and the server will return a 500 error.
            log_error "Error found in ItemsController#show. params: #{params}, user_id: #{current_user.id}, exception: #{exception}"
            
            # Freeze code exection.
            # Would be helpful to find where the code specifically field while pry is active. You can figure this out by doing exception.backtrace 
            # and it will return the call stack(file and methods used that led to this error).
            # You would remove this pry in production right before code review.
            # Pry gem can documentation can be found here: https://github.com/pry/pry
            binding.pry
        end
      
        if @item == nil
            flash[:notice] = "Item has not been found."
            redirect_to :index
        end
    end
end