Srikanth Jeeva's technical Blog

Rails has wonderful inbuilt caching methods. This is how i implemented caching for a particular action.   Requirement : Cache a page for 12 hours. After 12 hrs Caching must expire.   before_filter :clear_cache   caches_action :index, :layout => false def index       #code     # Write expiry time to cache (12 hours)     Rails.cache.write('expiry_time', Time.now + 12.hours) end def clear_cache     #Fetch time from cache and check with current time     t = Rails.cache.fetch('expiry_time') || Time.now     t = Time.parse(t) if t.is_a?(String)     # Expire action if current time > Cached time     expire_action :action => :index if Time.now > t  end Thanks!

Plugin git repo : https://github.com/platform45/easy_roles     Step 1 : Install Plugin script/plugin install git://github.com/platform45/easy_roles.git Step 2 : Generate migration to create column called roles in user's table rails g easy_roles user roles   Step 3 : Run. rake db:migrate to run the migration   Step 4 : Add this line to the user's model   class User < ActiveRecord::Base easy_roles :roles end Add users role, remove, check role as follows. @user = User.first  @user.add_role 'admin'  @user.is_admin?  => true      @user.has_role? 'admin'  => true    @user.is_awesome?  => false    @user.add_role 'awesome'    @user.is_awesome?  => true    @user.remove_role 'admin'    @user.is_admin?  => false 

>> rvm package install zlib ERROR: Unrecognized command line argument: 'package' ( see: 'rvm usage' ) The keyword 'package' is renamed to 'pkg' Try, >> rvm pkg install zlib Njjoy :)

Hi, I have got this below error. $ gem install rhodes-3.1.0.gem -l Building native extensions.  This could take a while... ERROR:  Error installing rhodes-3.1.0.gem:         ERROR: Failed to build gem native extension. c:/InstantRhodes/ruby/bin/ruby.exe extconf.rb make 'make' is not recognized as an internal or external command, operable program or batch file. Gem files will remain installed in c:/InstantRhodes/ruby/lib/ruby/gems/1.8/gems/ rhodes-3.1.0 for inspection. Results logged to c:/InstantRhodes/ruby/lib/ruby/gems/1.8/gems/rhodes-3.1.0/ext/ gem_make.out Here is the Fix: install Devkit for windows by following the steps, https://github.com/oneclick/rubyinstaller/wiki/development-kit -- Srikanth

  Hi, I have got this error No such file or directory 'Simulator' ltadmin@LT008029 ~/projects/SocialTango_Mobile (master) $ rake run:bb rake/rdoctask is deprecated.  Use rdoc/task instead (in RDoc 2.4.2+) $use_sqlite : false rake aborted! No such file or directory - C:/bb/5.0.0.621_9650/simulator This is how to Fix this, Fix 1. Check if you have installed the Blackberry JDE. If you have installed Blackberry JDE there will be a simulator folder and MDS folder inside the installed directory. (In case if you have not installed JDE, here is where you need to download http://us.blackberry.com/developers/javaappdev/javadevenv.jsp ) Fix 2. If you have installed JDE and got the error. Go to Rhodes installation path and find the rhobuild.yml. In my system the path is, C:\InstantRhodes\ruby\lib\ruby\gems\1.8\gems\rhodes-3.0.2\rhobuild.yml  check if this paths are correct in rhobuild.yml:     6.0:       jde: C:/Program Files/Research In ...

1. Download the Instant Rhodes installer from http://docs.rhomobile.com/rhodes/install#install-on-windows and install it.  This will install Ruby, Rhodes. 2.  Download the Blackberry JDE from http://us.blackberry.com/developers/javaappdev/javadevenv.jsp  Note :  For this you will need to create account and login to the blackberry website. 3. Create a sample rhodes app.  rhodes app myspace 4. Go to build.yml in the app, and change the version for blackberry,.  bbver: 6.0     5. do 'rhodes-setup' for adding Java path  $ rhodes-setup We will ask you a few questions below about your dev environment. JDK path (required) (C:/Program Files/Java/jdk1.6.0_21): C:/Program Files/Java/j dk1.6.0_21 for other paths just skip.  6. Go to Rhodes installation path and find the rhobuild.yml. In my system the path is, C:\InstantRhodes\ruby\lib\ruby\gems\1.8\gems\rhodes-3.0.2\rhobuild.yml add this lines in rhobuild.yml for blackberry version 6...

Error 1 : invalid command-line parameter: Files\Android\android-sdk\tools/emulator-arm.exe. Hint: use '@foo' to launch a virtual device named 'foo'. please use -help for more information Fix:  This problem is when you install Rhodes in the path "c:/Program Files/Android/android-sdk"  as there is a space in the word "Program Files". Try reinstalling to path "c:/Android/android-sdk" Error 2 :  sh.exe": /c/InstantRhodes/ruby/bin/rake: C:/RhoSync/ruby/bin/ruby.exe^M: bad interpreter: No such file or directory Fix : reinstall the rake gem. 1. gem uninstall rake 2. gem install rake This will update the rake Gem Error 3 : Cannot find your Rhodes gem or source path.  Fix :  run this in terminal. this will set up the rhodes path $ set-rhodes-sdk c:/InstantRhodes/ruby/lib/ruby/gems/1.8/gems/rhodes-3.0.2/bin

1. Install plugin script/plugin install http://calendardateselect.googlecode.com/svn/tags/calendar_date_select 2. Include JS & CSS to your layout file     <link href="/stylesheets/calendar_date_select/blue.css" media="screen" rel="stylesheet" type="text/css" />     <script src="/javascripts/calendar_date_select/calendar_date_select.js" type="text/javascript"></script> 3. Calendar date select tag <input type="text" name="user[date_of_birth]" size="30" autocomplete="off" onselect="new CalendarDateSelect( this, {year_range:50} );" onclick="new CalendarDateSelect( this, {year_range:50} );" value="<%= Date.today %>"/> Restart the server as the plugin has been installed! Calendar date select works! Notes : 1. If you wish to turn on the time, use this => new CalendarDateSelect( this, {year_range:50, time:true...

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Hi, In Rails 3. there was a problem with rake 0.9.0 gemset. When i do rake db:create I got the following error, undefined method `task' for # The fix is as follows, go to config/application.rb file. Add this line inside the class, include Rake::DSL That fixed the problem

Examples number_with_delimiter(12345678) # => 12,345,678 number_with_delimiter(12345678.05) # => 12,345,678.05 number_with_delimiter(12345678, :delimiter => ".") # => 12.345.678 number_with_delimiter(12345678, :separator => ",") # => 12,345,678 number_with_delimiter(12345678.05, :locale => :fr) # => 12 345 678,05 number_with_delimiter(98765432.98, :delimiter => " ", :separator => ",") Source : http://apidock.com/rails/ActionView/Helpers/NumberHelper/number_with_delimiter Learn : Agile Web Development with Rails | Beginning Rails 3

Wanna paginate an Array using will paginate.. Here is how i did.. Add this as method, Array.class_eval do def paginate(page=1, per_page=15) pagination_array = WillPaginate::Collection.new(page, per_page, self.size) start_index = pagination_array.offset end_index = start_index + (per_page - 1) array_to_concat = self[start_index..end_index] array_to_concat.nil? ? [] : pagination_array.concat(array_to_concat) end end And with the array @results do @results.paginate reference: http://www.devchix.com/2007/07/23/will_paginate-array/ Regards, Srikanth Learn to Program with Ruby | Ruby Pocket Reference

Hi, I have used this for sorting manually. @results.sort{|x, y| x.send(:created_at) y.send(:created_at)} P.S. @results is an array tht has many records. Concepts and Code

Hi I have used this function to load Google map with Marker and bounds. function initialize(lat, lon, div_id) { var myLatlng = new google.maps.LatLng(lat, lon); var myOptions = { zoom: 8, center: myLatlng, mapTypeId: google.maps.MapTypeId.ROADMAP } var bounds = new google.maps.LatLngBounds (); var map = new google.maps.Map(document.getElementById(div_id), myOptions); var trucklatlng = new google.maps.LatLng(lat,lon); var marker = new google.maps.Marker({ position: trucklatlng, map: map, title:"Assist" }); var LatLngListFake1 = new google.maps.LatLng(lat + 0.005 , lon + 0.005); var LatLngListFake2 = new google.maps.LatLng(lat - 0.005, lon - 0.005); bounds.extend(LatLngListFake1); bounds.extend(LatLngListFake2); map.fitBounds (bounds); } In the View File: Just call, <script>initialize(lat, lon, div_id)</script>

Rails - Active Record - Save without callbacks p = Post.first p.title = "test" p.send(:update_without_callbacks)

I have used Fastercsv gem to generate csv data and used send_data method.. def create_csv @customers = Customer.all csv_string = FasterCSV.generate do |csv| csv @customers.each do |customer| csv end end send_data csv_string, :filename => "customers.csv" , :type=>"text/csv" end

I have used this code to enable/disable textboxes in the onclick of a Checkbox $('#by_cheque').click(function() { if ($('#by_cheque').is(':checked')) { $('#payable_name').removeAttr('disabled'); } else { $('#payable_name').attr('disabled', 'disabled'); } });

Hi all, For using Google map v3, i always used with Javascript v3 provided by google. I didn't know there is an awesome plugin like this. anyways its not late.. Here is the GIT repo for it. https://github.com/parolkar/cartographer Also anyone knows more about Google map API plugins pls share ..

Hi I have used the following JS for page refresh automatically. function timedRefresh(timeoutPeriod) { setTimeout("location.reload(true);",timeoutPeriod); } <body onload="JavaScript:timedRefresh(120000);"> // 12000 - 2 minutes // 100 - 1 second

1. Register your APP here http://developers.facebook.com/setup , for local use your local URL ex). http://localhost:3000/ 2. Click Submit, and once registered it will take you to a page. 3. In that click on Developer Dashboard. 4. Check if your Site URL. 5. Copy your App credentials to your App yml file. fb_api_key: {your api key} fb_secret: {your fb secret} fb_app_id: {your app id}

For Facebook Graph API client. I checked a gem 'rest-graph' Here is the git repo https://github.com/godfat/rest-graph

Hi, I have came across this gem authlogic-connect. https://github.com/viatropos/authlogic-connect This provides Authentication with twitter, facebook, google, yahoo, myspace, vimeo, linked_in