Debugging on rails

Debugging on RailsMykhaylo Sorochan

kiev.rb #2kiev.rb #2

Contents

Sample app for the Ruby on Rails Tutorial (Rails 4)https://github.com/railstutorial/sample_app_rails_4

Debugged application

https://github.com/railstutorial/sample_app_rails_4

https://github.com/railstutorial/sample_app_rails_4

debugger

gem 'debugger'debugger - call debuggerconfig - .rdebugrc

Debug locationUserController#show

def show

@user = User.find(params[:id])

debugger

@microposts = @user.microposts.paginate(page: params[:page])

end

Debugger commands(rdb:9) help

ruby-debug help v1.6.2

Type 'help <command-name>' for help on a specific command

Available commands:

backtrace delete enable help list pry restart source undisplay

break disable eval info method ps save start up

catch display exit irb next putl set step var

condition down finish jump p quit show thread where

continue edit frame kill pp reload skip trace

Program info(rdb:4) help info

Generic command for showing things about the program being debugged.

--

List of info subcommands:

--

info args -- Argument variables of current stack frame

info breakpoints -- Status of user-settable breakpoints

info catch -- Exceptions that can be caught in the current stack frame

info display -- Expressions to display when program stops

info file -- Info about a particular file read in

info files -- File names and timestamps of files read in

info global_variables -- Global variables

info instance_variables -- Instance variables of the current stack frame

info line -- Line number and file name of current position in source file

info locals -- Local variables of the current stack frame

info program -- Execution status of the program

info stack -- Backtrace of the stack

info thread -- List info about thread NUM

info threads -- information of currently-known threads

info variables -- Local and instance variables of the current stack frame

Listing(rdb:1) help list

l[ist] list forward

l[ist] - list backward

l[ist] = list current line

l[ist] nn-mm list given lines

NOTE - to turn on autolist, use 'set autolist' -> .rdebugrc

Listing: in debug 12 @user = User.find(params[:id])

13 debugger

=> 14 @microposts = @user.microposts.paginate(page: params[:page])

15 end

16

Listing: l 23,25l 23,25

[23, 25] in */sample_app_rails_4/app/controllers/users_controller.rb

23 if @user.save

24 sign_in @user

25 flash[:success] = "Welcome to the Sample App!"

Breakpoints(rdb:4) help break

b[reak] file:line [if expr]

b[reak] class(.|#)method [if expr]

set breakpoint to some position, (optionally) if expr == true

(rdb:4) help delete

del[ete][ nnn...] delete some or all breakpoints

Set breakpoint(rdb:4) b ApplicationHelper#full_title

Breakpoint 1 at ApplicationHelper::full_title

(rdb:4) b 18

Breakpoint 2 file */sample_app_rails_4/app/controllers/users_controller.rb, line 18

(rdb:4) info b

Num Enb What

1 y at ApplicationHelper:full_title

2 y at */sample_app_rails_4/app/controllers/users_controller.rb:18

Navigate(rdb:4) help step

s[tep][+-]?[ nnn] step (into methods) once or nnn times

'+' forces to move to another line.

'-' is the opposite of '+' and disables the force_stepping setting.

(rdb:4) help next

n[ext][+-]?[ nnn] step over once or nnn times,

'+' forces to move to another line.

'-' is the opposite of '+' and disables the force_stepping setting.

(rdb:4) help up

up[count] move to higher frame

Stop at breakpoint(rdb:4) c

Breakpoint 1 at ApplicationHelper:full_title

[-1, 8] in */sample_app_rails_4/app/helpers/application_helper.rb

1 module ApplicationHelper

2

3 # Returns the full title on a per-page basis.

=> 4 def full_title(page_title)

5 base_title = "Ruby on Rails Tutorial Sample App"

Display(rdb:4) help display

disp[lay] <expression> add expression into display expression list

disp[lay] display expression list

(rdb:4) help undisplay

undisp[lay][ nnn]

Cancel some expressions to be displayed when program stops.

Display configured 4 def full_title(page_title)

=> 5 base_title = "Ruby on Rails Tutorial Sample App"

6 if page_title.empty?

(rdb:4) disp

2: controller_name = users

3: base_title =

Display changed(rdb:4) n

*/sample_app_rails_4/app/helpers/application_helper.rb:6

if page_title.empty?

2: controller_name = users

3: base_title = Ruby on Rails Tutorial Sample App

[1, 10] in */sample_app_rails_4/app/helpers/application_helper.rb

5 base_title = "Ruby on Rails Tutorial Sample App"

=> 6 if page_title.empty?

7 base_title

Conditional breakpoint(rdb:8) b ApplicationHelper#full_title if page_title=="Alexander"

Breakpoint 4 at ApplicationHelper::full_title

(rdb:8) c

Breakpoint 1 at ApplicationHelper:full_title

Variables(rdb:8) help var

v[ar] cl[ass] show class variables of self

v[ar] co[nst] <object> show constants of object

v[ar] g[lobal] show global variables

v[ar] i[nstance] <object> show instance variables of object. You may pass object id's hex as well.

v[ar] l[ocal] show local variables

Show variables 12 @user = User.find(params[:id])

13 debugger


15 end

16

17 def new

(rdb:12) v i

@_action_has_layout = true

@_action_name = "show"

@_config = {}

@_env = {"GATEWAY_INTERFACE"=>"CGI/1.1", "PATH_INFO"=>"/users/1", "QUERY_STRING"=>"",...

@_headers = {"Content-Type"=>"text/html"}

@_lookup_context = #<ActionView::LookupContext:0x00000008e4b710 @details_key=nil, @details={:loc...

@_params = {"action"=>"show", "controller"=>"users", "id"=>"1"}

@_prefixes = ["users", "application"]

@_request = #<ActionDispatch::Request:0x00000008e4bad0 @env={"GATEWAY_INTERFACE"=>"CGI/1....

@_response = #<ActionDispatch::Response:0x00000008e4baa8 @mon_owner=nil, @mon_count=0, @mo...

@_response_body = nil

@_routes = nil

@_status = 200

@user = #<User id: 1, name: "Alexander", email: "[email protected]", created_at: "2013-11...

Remote debugger

Client# rdebug --client -h 127.0.0.1

Connected.

*/sample_app_rails_4/app/controllers/users_controller.rb:14

@microposts = @user.microposts.paginate(page: params[:page])

[9, 18] in */sample_app_rails_4/app/controllers/users_controller.rb

9 end

10

11 def show

12 @user = User.find(params[:id])

13 debugger


ServerDebugger.wait_connection = true

Debugger.start_remote

pry

REPL

debugger-pry

Call pry from debugger

pry-debugger

Debugger commands inside pry:step, next, continue, breakpoints

jazz_hands

jazz_hands is an opinionated set of console-related gems and a bit of glue:pry, awesome_print, hirb, pry-rails, pry-doc, pry-git, pry-remote, pry-debugger, pry-stack_explorer, coolline, coderay

pry – jazz_hands 1




Logging

ActiveSupport::Logger is used for logging

Rails.root/log/[environment_name].log

Log levelsRails.logger.level

| name | level |

|----------+-------|

| :debug | 0 |

| :info | 1 |

| :warn | 2 |

| :error | 3 |

| :fatal | 4 |

| :unknown | 5 |

development, testing: log_level = 0 (:debug)production: log_level = 1

Messages with equal or higher level are sent to log

Write to loglogger.debug User.inspect

logger.info user.id

logger.fatal "Help!"

Tagging log messageslogger = ActiveSupport::TaggedLogging.new(Logger.new(STDOUT))

logger.tagged("USER") { logger.info "hello" }

=> [USER] hello

Tagged logging

def show

@user = User.find(params[:id])

logger.tagged("USER") { logger.info @user.email }

# tail -f log/development.log|grep \\\[USER\]

[USER] [email protected]

Global variables for tracing__FILE__ - file name

__LINE__ - line number

Some useful CLI commandstail -n 100

tail -f

grep, less

Querying logs# cat log/development.log|grep GET|tail -n 2

Started GET "/assets/users.js?body=1" for 127.0.0.1 at 2013-11-21 23:32:01 +0200

Started GET "/assets/application.js?body=1" for 127.0.0.1 at 2013-11-21 23:32:01 +0200

# cat log/development.log|grep GET|wc -l

574

config.log_formatterDefines the formatter of the Rails logger. Defaults to ActiveSupport::Logger::SimpleFormatter for all modes, production defaults to Logger::Formatter.

module ActiveSupport

class Logger < ::Logger

# Simple formatter which only displays the message.

class SimpleFormatter < ::Logger::Formatter

# This method is invoked when a log event occurs

def call(severity, timestamp, progname, msg)

"#{String === msg ? msg : msg.inspect}\n"

end

end

config.log_levelDefaults to :debug for all modes, production defaults to :info.

config.log_tagsSee ActionDispatch::Request methods. config.log_tags = [ :fullpath ]

[/users/1] Started GET "/users/1" for 127.0.0.1 at 2013-11-...

[/users/1] ActiveRecord::SchemaMigration Load (0.1ms) SELECT ...

[/assets/application.css?body=1] Started GET "/assets/application.css?body=1" for 127...

config.loggerAccepts a logger conforming to the interface of Log4r or the default Ruby Logger class. Defaults to ActiveSupport::Logger, with auto flushing off in production mode.

Rails consolerails c

rails c --sandbox

irb

pry

rake routes> all_routes = Rails.application.routes.routes

> require 'action_dispatch/routing/inspector'

> inspector = ActionDispatch::Routing::RoutesInspector.new(all_routes)

All routes> puts inspector.format(ActionDispatch::Routing::ConsoleFormatter.new)

Prefix Verb URI Pattern Controller#Action

following_user GET /users/:id/following(.:format) users#following

followers_user GET /users/:id/followers(.:format) users#followers

users GET /users(.:format) users#index

POST /users(.:format) users#create

new_user GET /users/new(.:format) users#new

edit_user GET /users/:id/edit(.:format) users#edit

user GET /users/:id(.:format) users#show

PATCH /users/:id(.:format) users#update

PUT /users/:id(.:format) users#update

DELETE /users/:id(.:format) users#destroy

sessions POST /sessions(.:format) sessions#create

new_session GET /sessions/new(.:format) sessions#new

session DELETE /sessions/:id(.:format) sessions#destroy

microposts POST /microposts(.:format) microposts#create

micropost DELETE /microposts/:id(.:format) microposts#destroy

relationships POST /relationships(.:format) relationships#create

relationship DELETE /relationships/:id(.:format) relationships#destroy

root GET / static_pages#home

signup GET /signup(.:format) users#new

Routes for controller> puts inspector.format(ActionDispatch::Routing::ConsoleFormatter.new, 'microposts')

Prefix Verb URI Pattern Controller#Action

microposts POST /microposts(.:format) microposts#create

micropost DELETE /microposts/:id(.:format) microposts#destroy

Filtering routes: GET> puts inspector.format(ActionDispatch::Routing::ConsoleFormatter.new, 'users').lines.grep(/GET/).join

following_user GET /users/:id/following(.:format) users#following

followers_user GET /users/:id/followers(.:format) users#followers

users GET /users(.:format) users#index

new_user GET /users/new(.:format) users#new

edit_user GET /users/:id/edit(.:format) users#edit

user GET /users/:id(.:format) users#show

signup GET /signup(.:format) users#new

Filtering routes: /relation/> puts inspector.format(ActionDispatch::Routing::ConsoleFormatter.new).lines.grep(/relation/).join

relationships POST /relationships(.:format) relationships#create

relationship DELETE /relationships/:id(.:format) relationships#destroy

Matching routes> r = Rails.application.routes

> r.recognize_path "/users/47"

=> {:action=>"show", :controller=>"users", :id=>"47"}

> r.recognize_path "/users/87", :method => "PUT"

=> {:action=>"update", :controller=>"users", :id=>"87"}

> r.recognize_path "/users/47.json"

=> {:action=>"show", :controller=>"users", :id=>"47", :format=>"json"}

Named routes> app.users_path

=> "/users"

> app.users_path(:json)

=> "/users.json"

> app.user_path(1)

=> "/users/1"

> app.user_path(1, :xml)

=> "/users/1.xml"

> app.user_path(1, :count => 4)

=> "/users/1?count=4"

Making requests> app

=> #<ActionDispatch::Integration::Session:...>

> app.reset!

Get requests> app.get '/users/1/edit'

Started GET "/users/1/edit" for 127.0.0.1 at 2013-11-26 23:24:18 +0200

Processing by UsersController#edit as HTML

Parameters: {"id"=>"1"}

Redirected to http://localhost:3000/signin

Filter chain halted as :signed_in_user rendered or redirected

Completed 302 Found in 3ms (ActiveRecord: 0.4ms)

> app.response.body

=> "<html><body>You are being <a href=\"http://localhost:3000/signin\">redirected</a>.</body></html>"

> app.get_via_redirect '/users/1/edit'


Redirected to http://localhost:3000/signin

...

Started GET "/signin" for 127.0.0.1 at 2013-11-26 23:26:44 +0200

Session cookies> app.cookies

=> #<Rack::Test::CookieJar...

> app.cookies.to_hash

=> {"_sample_app_session"=>"RC9j...

app.cookies - received/sent cookies

Post requests: signin> app.response.body.lines.grep /csrf-token/

=> ["<meta content=\"n+9uCcG2JJmgwhnNcp4s9jTwOU55RAPOdtAHWstcpKQ=\" name=\"csrf-token\" />\n"]

> app.post '/sessions', :authenticity_token => 'n+9uCcG2JJmgwhnNcp4s9jTwOU55RAPOdtAHWstcpKQ=',

'session[email]' => '[email protected]', 'session[password]' => '123456'

Started POST "/sessions" for 127.0.0.1 at 2013-11-26 23:33:01 +0200

Processing by SessionsController#create as HTML

Parameters: {"authenticity_token"=>"n+9uCcG2JJmgwhnNcp4s9jTwOU55RAPOdtAHWstcpKQ=", "session"=>{"email"=>"[email protected]", "password"=>"[FILTERED]"}}

Redirected to http://localhost:3000/users/1/edit

Completed 302 Found in 281ms (ActiveRecord: 7.2ms)

app.post_via_redirect

Access to restricted resource> app.get '/users/1/edit'


Processing by UsersController#edit as HTML

Completed 200 OK in 41ms (Views: 35.7ms | ActiveRecord: 0.8ms)

Call helper> helper

=> #<ActionView::Base:... >

# ApplicationHelper#full_title

> helper.full_title "Sign Up"

=> "Ruby on Rails Tutorial Sample App | Sign Up"

Call helper with cookie> def cookies; @cookies ||= HashWithIndifferentAccess.new(app.cookies.to_hash); end

> helper.current_user

=> #<User id: 1, name: ....

ActiveRecord logging> ActiveRecord::Base.logger = Logger.new(STDOUT)

> ActiveRecord::Base.clear_active_connections!

> # reload!

> User.find 1

D, [2013-12-30T21:55:17.775769 #24810] DEBUG -- : User Load (0.2ms) SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT 1 [["id", 1]]

=> #<User id: 1, name: "hello",....

ActiveRecord hide logging> ActiveRecord::Base.logger = Logger.new(nil)

> ActiveRecord::Base.clear_active_connections!

> # reload!

> User.find 1

=> #<User id: 1, name: "hello",....

Raw SQL requests> ActiveRecord::Base.connection.select_all("select * from users")

=> #<ActiveRecord::Result:...

> puts _

{"id"=>1, "name"=>"hello", "email"=>"[email protected]", "created_at"=>"2013-....

.irbrc

Save your helper methods● routes● sql logging● etc

CLI tools

Making HTTP requests with curl● -s silent● -v verbose● -c save cookie● -b use cookie● -data POST data● -data-urlencode URL-encode POST data

Access restricted areacurl -s -v http://localhost:3000/users/1/edit > /dev/null

> GET /users/1/edit HTTP/1.1

< HTTP/1.1 302 Found

< Location: http://localhost:3000/signin

Visit /signin, get tokencurl -s -c hello_cookies http://localhost:3000/signin > /dev/null |grep csrf-token

<meta content="/t/IoUQxKVEL+KR2/HsnxTKmnALUA99jIr/LvjlgPKs=" name="csrf-token" />

Sign incurl -s -v --data "session[email][email protected];session[password]=123456" \

--data-urlencode "authenticity_token=/t/IoUQxKVEL+KR2/HsnxTKmnALUA99jIr/LvjlgPKs=" \

-b hello_cookies -c cookies \

http://localhost:3000/sessions > /dev/null

> POST /sessions HTTP/1.1

< HTTP/1.1 302 Found

< Location: http://localhost:3000/users/1

Successful access to restricted areacurl -s -v http://localhost:3000/users/1/edit -b cookies > /dev/null

> GET /users/1/edit HTTP/1.1

< HTTP/1.1 200 OK

Browser tools

● console● render helpers● debug info● etc

rack-webconsole>> User.find 1

=> #<User id: 1, name: "Alexander", email: "[email protected]", created_at: "2013-11-17 16:19:07", updated_at: "2013-11-27 21:52:06", password_digest: "$2a$10$MEICr2zekeBhh9HYCMLmXut3ckOsiL0TkksFWVX4asFf...", remember_token: "cda4da34a5ee4238ddb78f20d4ec7e52b59fab4e", admin: nil>

>> helper

=> Error: undefined local variable or method `helper' for #<Rack::Webconsole::Sandbox:0x000000089cf600>

>> app

=> Error: undefined local variable or method `app' for #<Rack::Webconsole::Sandbox:0x000000089cf600>

>> Rails.root

=> #<Pathname:*/sample_app_rails_4>

>> self

=> #<Rack::Webconsole::Sandbox:0x000000089cf600 @locals={:u=>#<User id: 1, name: "Alexander"

rack-webconsole

` - activate

Rails Panel

rails-footnotes: Assigns

rails-footnotes: DB

rails-footnotes: disable?footnotes=false

xray-railsCtrl+Shift+X

better_errors 1

better_errors 2

exception_notifier

Provides a set of notifiers for sending notifications when errors occur in a Rack/Rails application

letter_opener

Preview email in the browser instead of sending it

exception_notifier + letter_opener

Chrome: Form Editor

Chrome: JunkFill

Chrome: Sight

API calls, sight

hurl.it: params

hurl.it: response

POSTMAN

Chrome: REST console

Chrome: Advanced Rest Client

ВСЁ

Technology

Debugging on rails