Hi all, Like most other frameworks, Ruby groups code by Model/View/Controller instead of by task, and therefore I''m having a hard time debugging a problem from the Agile Rails book where looping through @items errors out because one or more items is nil. I managed to empty the cart by placing session[:cart] = nil in find_cart() in the store_controller_rb, and the problem continued after I removed that diagnostic, thereby proving it wasn''t caused just a bad record that got in there. I''ve examined the dump screen produced by the error every way but loose and can''t find anything that helps. I went back and looked at everything I did recently -- nothing obvious. I looked at log/production.log, and saw an error pointing to code I didn''t write (Rails code, in other words). I''d like to place diagnostic prints in the controller code to see if I''m placing nil records in the @items whatever, but where would such diagnostic prints print out? So I need some debugging tips. What are your favorite Rails debugging techniques? Thanks SteveT Steve Litt Author: * Universal Troubleshooting Process courseware * Troubleshooting Techniques of the Successful Technologist * Rapid Learning: Secret Weapon of the Successful Technologist Webmaster * Troubleshooters.Com * http://www.troubleshooters.com
I like to use breakpoints in the code and invoke script/breakpointer. It drops me into irb and ALL the environment vars of the controller are available. You can ctrl-D to continue and if your breakpoint() is in a loop you will hit it each time and see the vars changing. -bakki kudva On 1/6/06, Steve Litt <slitt@troubleshooters.com> wrote: ...> I''d like to place diagnostic prints in the controller code to see if I''m > placing nil records in the @items whatever, but where would such > diagnostic > prints print out? > > So I need some debugging tips. What are your favorite Rails debugging > techniques? > > Thanks > > SteveT > > _______________________________________________ > Rails mailing list > Rails@lists.rubyonrails.org > http://lists.rubyonrails.org/mailman/listinfo/rails >-------------- next part -------------- An HTML attachment was scrubbed... URL: http://wrath.rubyonrails.org/pipermail/rails/attachments/20060106/b865b58d/attachment-0001.html
On Jan 6, 2006, at 1:56 PM, Steve Litt wrote:> Hi all, > > Like most other frameworks, Ruby groups code by Model/View/ > Controller instead > of by task, and therefore I''m having a hard time debugging a > problem from the > Agile Rails book where looping through @items errors out because > one or more > items is nil. > > I managed to empty the cart by placing session[:cart] = nil in > find_cart() in > the store_controller_rb, and the problem continued after I removed > that > diagnostic, thereby proving it wasn''t caused just a bad record that > got in > there. I''ve examined the dump screen produced by the error every > way but > loose and can''t find anything that helps. I went back and looked at > everything I did recently -- nothing obvious. I looked at log/ > production.log, > and saw an error pointing to code I didn''t write (Rails code, in other > words). > > I''d like to place diagnostic prints in the controller code to see > if I''m > placing nil records in the @items whatever, but where would such > diagnostic > prints print out? > > So I need some debugging tips. What are your favorite Rails debugging > techniques? > > Thanks > > SteveTSteve- One good way to debug nil errors in your views is to use the debug method. So if your looping over @items try this at the top of your view: <%= debig(@items) %> You will get a pretty printed yaml version of your object and all the data it holds. And another way to avoid the nil errors inside of a loop is to do something like this: <% @items.each do |item| -%> <p><%= item.name rescue nil -%></p> <p><%= item.info rescue nil -%></p> <% end -%> The rescue nil deal will just print an empty string instead of making your whole page error out with a nil error when item.whatever is nil inside the loop. Hope that helps a bit. Cheers- -Ezra Zygmuntowicz Yakima Herald-Republic WebMaster http://yakimaherald.com 509-577-7732 ezra@yakima-herald.com
On Friday 06 January 2006 05:04 pm, Bakki Kudva wrote:> I like to use breakpoints in the code and invoke script/breakpointer. It > drops me into irb and ALL the environment vars of the controller are > available. You can ctrl-D to continue and if your breakpoint() is in a loop > you will hit it each time and see the vars changing. > > -bakki kudvaSounds good Bakki, How do I set a breakpoint? Thanks SteveT> On 1/6/06, Steve Litt <slitt@troubleshooters.com> wrote: > ... > > > I''d like to place diagnostic prints in the controller code to see if I''m > > placing nil records in the @items whatever, but where would such > > diagnostic > > prints print out? > > > > So I need some debugging tips. What are your favorite Rails debugging > > techniques? > > > > Thanks > > > > SteveT > > > > _______________________________________________ > > Rails mailing list > > Rails@lists.rubyonrails.org > > http://lists.rubyonrails.org/mailman/listinfo/rails
No-one''s mentioned logging yet. In a controller, you can write this: logger.info "My Stuff: #(@items.inspect)" And this output shows up in the log/development.log file. The logging functionality is more important to me than the IRB solution, as I can leave it in the code and check the log output if I seem something break. More info here: http://wiki.rubyonrails.com/rails/pages/HowtoConfigureLogging http://wiki.rubyonrails.com/rails/pages/logger -----Original Message----- From: rails-bounces@lists.rubyonrails.org [mailto:rails-bounces@lists.rubyonrails.org] On Behalf Of Steve Litt Sent: Friday, January 06, 2006 3:13 PM To: rails@lists.rubyonrails.org Subject: Re: [Rails] I need debugging tips? On Friday 06 January 2006 05:04 pm, Bakki Kudva wrote:> I like to use breakpoints in the code and invoke script/breakpointer. It > drops me into irb and ALL the environment vars of the controller are > available. You can ctrl-D to continue and if your breakpoint() is in aloop> you will hit it each time and see the vars changing. > > -bakki kudvaSounds good Bakki, How do I set a breakpoint? Thanks SteveT> On 1/6/06, Steve Litt <slitt@troubleshooters.com> wrote: > ... > > > I''d like to place diagnostic prints in the controller code to see if I''m > > placing nil records in the @items whatever, but where would such > > diagnostic > > prints print out? > > > > So I need some debugging tips. What are your favorite Rails debugging > > techniques? > > > > Thanks > > > > SteveT > > > > _______________________________________________ > > Rails mailing list > > Rails@lists.rubyonrails.org > > http://lists.rubyonrails.org/mailman/listinfo/rails_______________________________________________ Rails mailing list Rails@lists.rubyonrails.org http://lists.rubyonrails.org/mailman/listinfo/rails
On Friday 06 January 2006 06:19 pm, Tom Fakes wrote:> No-one''s mentioned logging yet. > > In a controller, you can write this: > > logger.info "My Stuff: #(@items.inspect)" > > And this output shows up in the log/development.log file. > > The logging functionality is more important to me than the IRB solution, as > I can leave it in the code and check the log output if I seem something > break. > > More info here: > http://wiki.rubyonrails.com/rails/pages/HowtoConfigureLogging > http://wiki.rubyonrails.com/rails/pages/loggerOh Oh, undefined local variable or method `logger'' for #<Cart:0x407f5e2c> This happened before and after I added the following to the bottom of config/environment.rb: begin RAILS_DEFAULT_LOGGER = Logger.new("#{RAILS_ROOT}/log/#{RAILS_ENV}.log") rescue StandardError RAILS_DEFAULT_LOGGER = Logger.new(STDERR) RAILS_DEFAULT_LOGGER.level = Logger::WARN RAILS_DEFAULT_LOGGER.warn( "Rails Error: Unable to access log file. Please ensure that log/#{RAILS_ENV}.log exists and is chmod 0666. " + "The log level has been raised to WARN and the output directed to STDERR until the problem is fixed." ) end [ActiveRecord, ActionController, ActionMailer].each { |mod| mod::Base.logger ||= RAILS_DEFAULT_LOGGER }
On Friday 06 January 2006 05:10 pm, Ezra Zygmuntowicz wrote:> Steve- > > One good way to debug nil errors in your views is to use the debug > method. So if your looping over @items try this at the top of your view: > > <%= debig(@items) %> > > You will get a pretty printed yaml version of your object and all > the data it holds.I tried that and didn''t see any nils, unless the dash at the bottom, with nothing after it, indicates a nil. Does that lone dash indicate a nil? Thanks Steve
The logger variable is part of your controller. Your original question was:
"I''d like to place diagnostic prints in the controller code to see
if I''m
placing nil records in the @items whatever, but where would such diagnostic
prints print out?"
So, this will work:
class MyController < ApplicationController
def some_action
logger.info "My Cart Is: #{@cart.inspect}"
end
end
But your current problem is that you are trying to log from a Model object
that is not derived from the ActiveRecord::Base class. In that case you
have to do use the RAILS_DEFAULT_LOGGER global constant:
class Cart
def something
RAILS_DEFAULT_LOGGER.info "My Cart Is: #{self.inspect}"
end
end
If you are using Rails 1.0, the code you added to environment.rb is not
necessary, it is built into Rails.
-----Original Message-----
From: rails-bounces@lists.rubyonrails.org
[mailto:rails-bounces@lists.rubyonrails.org] On Behalf Of Steve Litt
Sent: Friday, January 06, 2006 3:40 PM
To: rails@lists.rubyonrails.org
Subject: Re: [Rails] I need debugging tips?
On Friday 06 January 2006 06:19 pm, Tom Fakes wrote:> No-one''s mentioned logging yet.
>
> In a controller, you can write this:
>
> logger.info "My Stuff: #(@items.inspect)"
>
> And this output shows up in the log/development.log file.
>
> The logging functionality is more important to me than the IRB solution,
as> I can leave it in the code and check the log output if I seem something
> break.
>
> More info here:
> http://wiki.rubyonrails.com/rails/pages/HowtoConfigureLogging
> http://wiki.rubyonrails.com/rails/pages/logger
Oh Oh,
undefined local variable or method `logger'' for
#<Cart:0x407f5e2c>
This happened before and after I added the following to the bottom of
config/environment.rb:
begin
RAILS_DEFAULT_LOGGER =
Logger.new("#{RAILS_ROOT}/log/#{RAILS_ENV}.log")
rescue StandardError
RAILS_DEFAULT_LOGGER = Logger.new(STDERR)
RAILS_DEFAULT_LOGGER.level = Logger::WARN
RAILS_DEFAULT_LOGGER.warn(
"Rails Error: Unable to access log file. Please ensure that
log/#{RAILS_ENV}.log exists and is chmod 0666. " +
"The log level has been raised to WARN and the output directed to
STDERR
until the problem is fixed."
)
end
[ActiveRecord, ActionController, ActionMailer].each { |mod| mod::Base.logger
||= RAILS_DEFAULT_LOGGER }
_______________________________________________
Rails mailing list
Rails@lists.rubyonrails.org
http://lists.rubyonrails.org/mailman/listinfo/rails
On Jan 6, 2006, at 3:46 PM, Steve Litt wrote:> On Friday 06 January 2006 05:10 pm, Ezra Zygmuntowicz wrote: > >> Steve- >> >> One good way to debug nil errors in your views is to use the debug >> method. So if your looping over @items try this at the top of your >> view: >> >> <%= debig(@items) %> >> >> You will get a pretty printed yaml version of your object and all >> the data it holds. > > I tried that and didn''t see any nils, unless the dash at the > bottom, with > nothing after it, indicates a nil. Does that lone dash indicate a nil? > > Thanks > > SteveI think it does, but could you paste the debug yaml dump here and I can tell you? Cheers- -Ezra Zygmuntowicz WebMaster Yakima Herald-Republic Newspaper ezra@yakima-herald.com 509-577-7732
Just insert breakpoint() in your ruby code which you want to examine. Invoke script/breakpointer and you should see.. No connection to breakpoint service at druby://localhost:42531(DRb::DRbConnError) Tries to connect will be made every 2 seconds... Don''t worry about the ''No connection at breakpoint'' bit. Carry on with your app and when the breakpoint hits you will see something like: Executing break point at ./script/../config/../app/controllers/my_controller.rb:16 in `new'' irb(#<MyController:0x4079fef0>):001:0> Which means you are in irb. Now you can simply type in variable names and look at their values. The best documentation I found for the breakpointer is in its source file which is at: /usr/lib/ruby/gems/1.8/gems/activesupport-1.2.5/lib/active_support/breakpoint.rb on my Debian system. hope it helps, bakki On 1/6/06, Steve Litt <slitt@troubleshooters.com> wrote:> > On Friday 06 January 2006 05:04 pm, Bakki Kudva wrote: > > I like to use breakpoints in the code and invoke script/breakpointer. It > > drops me into irb and ALL the environment vars of the controller are > > available. You can ctrl-D to continue and if your breakpoint() is in a > loop > > you will hit it each time and see the vars changing. > > > > -bakki kudva > > Sounds good Bakki, > > How do I set a breakpoint? > > Thanks > > SteveT > > > On 1/6/06, Steve Litt <slitt@troubleshooters.com> wrote: > > ... > > > > > I''d like to place diagnostic prints in the controller code to see if > I''m > > > placing nil records in the @items whatever, but where would such > > > diagnostic > > > prints print out? > > > > > > So I need some debugging tips. What are your favorite Rails debugging > > > techniques? > > > > > > Thanks > > > > > > SteveT > > > > > > _______________________________________________ > > > Rails mailing list > > > Rails@lists.rubyonrails.org > > > http://lists.rubyonrails.org/mailman/listinfo/rails > _______________________________________________ > Rails mailing list > Rails@lists.rubyonrails.org > http://lists.rubyonrails.org/mailman/listinfo/rails >-------------- next part -------------- An HTML attachment was scrubbed... URL: http://wrath.rubyonrails.org/pipermail/rails/attachments/20060107/f49bd6b3/attachment.html
How does one single step through the code? I have tried irb and it doenst allow me to do that! On 1/7/06, Steve Litt <slitt@troubleshooters.com> wrote:> > On Friday 06 January 2006 05:10 pm, Ezra Zygmuntowicz wrote: > > > Steve- > > > > One good way to debug nil errors in your views is to use the debug > > method. So if your looping over @items try this at the top of your view: > > > > <%= debig(@items) %> > > > > You will get a pretty printed yaml version of your object and all > > the data it holds. > > I tried that and didn''t see any nils, unless the dash at the bottom, with > nothing after it, indicates a nil. Does that lone dash indicate a nil? > > Thanks > > Steve > _______________________________________________ > Rails mailing list > Rails@lists.rubyonrails.org > http://lists.rubyonrails.org/mailman/listinfo/rails >-------------- next part -------------- An HTML attachment was scrubbed... URL: http://wrath.rubyonrails.org/pipermail/rails/attachments/20060109/616566b5/attachment.html