Web Professional

change table column name in Rails validation message

noreply@blogger.com (Chirag Shah) — Tue, 20 Sep 2011 05:39:23 PDT

class Vendor < ActiveRecord::Base

validate_uniqness_of :gid, :message => "should be uniq"

HUMANIZED_ATTRIBUTES = {
    :gid => "vendor"
  }

  def self.human_attribute_name(attr)
    HUMANIZED_ATTRIBUTES[attr.to_sym] || super
  end

end

Collect all child elements javascript

noreply@blogger.com (Chirag Shah) — Fri, 08 Jul 2011 04:19:43 PDT

For all first level children
var children = document.getElementById('id').childNodes;

For all descendants
var children = document.getElementById('id').getElementsByTagName('*');

For some particular element children
var childNodeArray = document.getElementById(tbody).getElementsByTagName('tr');

find process id for the port

noreply@blogger.com (Chirag Shah) — Mon, 28 Mar 2011 03:56:49 PDT

Find port by following way

lsof -w -n -i tcp:8080
fuser -n tcp 8080

Now you have some integer value which is the process of the port
Now kill it by
kill -9 XXXX

Debuging Technique with Ruby on Rails

noreply@blogger.com (Chirag Shah) — Fri, 25 Mar 2011 22:38:10 PDT

There are multiple debug techniques are available with RoR, Please use the
below techniques as much as you can, while you do programming in RoR.

1. install ruby-debug
   then need to start application by ruby script/server --debugger
   And place word 'debugger' anywhere in your code and once you run your
application, it stops running from where you have placed 'debugger'. We
can say that debugger is the breakpoint

Then you can use following commands
n - move next line
l - display the current line after the debugger
c - continue
You can also check the readme of the ruby-debug

2. You can use puts,exit etc.

3. You can use logger.debug "The object is #{@object}" or
RAILS_DEFAULT_LOGGER.debug @object

4. In view, you can also use <%=debug @object %>

5. You can simultaneously check your log by running tail -f lod/development.log in the another terminal or you can also use tail -n log/development.log where n is any numeric number

6. We can use Exception Notifier plugin in our production environment so that we gets an notification mail if any error occurs on production

Call Rake task from migration

noreply@blogger.com (Chirag Shah) — Sun, 23 Jan 2011 22:48:58 PST

You can call the rake task in migration by writing following

Rake::Task[this_is_rake_task'].invoke

Is the string has numeric value?

noreply@blogger.com (Chirag Shah) — Sun, 23 Jan 2011 22:46:34 PST

for check the string has numeric value or not then you can do it by below
s = "123cs"

then call method as below
is_numeric?(s)

and the method is as below
def is_numeric?(s)
s.to_s.match(/\A[+-]?\d+?(\.\d+)?\Z/) == nil ? false : true
end

Run your rails application with apache2 and mongrel_clusters

noreply@blogger.com (Chirag Shah) — Sun, 23 Jan 2011 22:43:17 PST

Run your rails application with apache2 and mongrel_clusters

Install Apache 2.2 and enable the needed modules (url rewriting, proxy, proxy_balancer e proxy_http)

sudo apt-get install apache2

# enable your modules in apache
sudo a2enmod rewrite
sudo a2enmod proxy
sudo a2enmod proxy_balancer
sudo a2enmod proxy_http
sudo a2enmod proxy_connect

# if you not enabled any of the modules then may be errors occured while you restart your apache after adding the below configration
# Error may be encoutered it yoou have not enabled module rewrite is "Invalid command 'RewriteEngine', perhaps misspelled or defined by a module not included in the server configuration"

Install Mongrel, create a mongrel user, create the mongrel cluster
sudo gem install daemons gem_plugin mongrel mongrel_cluster --include-dependencies

You can continue with the same linux user to mongrel if you want otherwise you can create new user by
sudo /usr/sbin/adduser mongrel
This line creates new user mongrel withg same mongrel group
Now need to create one mongrel_cluster.yml
sudo mongrel_rails cluster::configure -e production -p 3010 -N 2 -c /home/user/projects/myapp -a 127.0.0.1 --user mongrel --group mongrel

here -e = your working environment
     -p = your port for run application
     -N = Number of instances of the application. here 2 instances for my application and port is 3010. so this application will work on 3010 and 3011 port
--user = need to provide your linuxuser
--group = need to provide your linuxgroup

this line will create /config/mongrel_cluster.yml file with following command
user: mongrel
cwd: /home/user/projects/myapp
log_file: log/mongrel.log
port: "3010"
environment: production
group: mongrel
address: 127.0.0.1
pid_file: tmp/pids/mongrel.pid
servers: 2

now make sure that tmp and log folder has permission to the user/group which you have user in mongrel_cluster if not assign permission by
sudo chown -R mongrel:mongrel /path/to/app/tmp

# Now start mongrel clusters
sudo mongrel_rails cluster::start

Hopefully clusters is worked perfactly and you can get it run on multiple port 3010 and 3011
http://127.0.0.1:3010
http://127.0.0.1:3011

Now need to set proxy balancer for this app
For this need to create one host for you app
Go to sudo nano /etc/hosts

127.0.0.1 localhost
127.0.0.1 myapp

Now need to configure Apache configuration file (sudo gedit /etc/apache2/sites-available/default).

NameVirtualHost *:80

#we need this as on Ubuntu/debian by default Proxy is not allowed
<Proxy *>
Order allow,deny
Allow from all
</Proxy>

#Proxy balancer section (create one for each ruby app cluster)
<Proxy balancer://myapp_cluster>
    BalancerMember http://myapp:3010
    BalancerMember http://myapp:3011
</Proxy>

#Virtual host section (create one for each ruby app you need to publish)
<VirtualHost *:80>
   ServerAdmin webmaster@localhost
        ServerName myapp
        DocumentRoot /home/user/projects/myapp/public/
    <Directory />
       Options FollowSymLinks
       AllowOverride None
    </Directory>
    <Directory /home/debian/chirag/mycalltime/public/>
       Options Indexes FollowSymLinks MultiViews
       AllowOverride All
       Order allow,deny
       allow from all
    </Directory>

   ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/
    <Directory "/usr/lib/cgi-bin">
       AllowOverride None
       Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
       Order allow,deny
       Allow from all
    </Directory>

   ErrorLog /var/log/apache2/error.log

   # Possible values include: debug, info, notice, warn, error, crit,
   # alert, emerg.
   LogLevel warn

   CustomLog /var/log/apache2/access.log combined

    Alias /doc/ "/usr/share/doc/"
    <Directory "/usr/share/doc/">
        Options Indexes MultiViews FollowSymLinks
        AllowOverride None
        Order deny,allow
        Deny from all
        Allow from 127.0.0.0/255.0.0.0 ::1/128
    </Directory>

#Rewrite stuff
RewriteEngine On

# Check for maintenance file and redirect all requests
RewriteCond %{DOCUMENT_ROOT}/system/maintenance.html -f
RewriteCond %{SCRIPT_FILENAME} !maintenance.html
RewriteRule ^.*$ /system/maintenance.html [L]

# Rewrite index to check for static
RewriteRule ^/$ /index.html [QSA]

# Rewrite to check for Rails cached page
RewriteRule ^([^.]+)$ $1.html [QSA]

# Redirect all non-static requests to cluster
RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_FILENAME} !-f
RewriteRule ^/(.*)$ balancer://myapp_cluster%{REQUEST_URI} [P,QSA,L]

</VirtualHost>

After configure the default file need to restart apache
sudo /etc/init.d/apache2 restart

Cheers....
You get your app running on multiple instanses with proxy balancer
http://myapp

search gem from repository

noreply@blogger.com (Chirag Shah) — Tue, 10 Aug 2010 04:59:23 PDT

If you want to find a gem in the repository then you can do it by following way

gem1.8 list -r | grep gem_name

Unpacked gem authlogic-2.1.3 in vendor/gems has no specification file. Run 'rake gems:refresh_specs' to fix this.

noreply@blogger.com (Chirag Shah) — Wed, 30 Jun 2010 01:42:47 PDT

You can solve this issue by following way

> cd vendor/gems/authlogic-2.1.3
> gem specification authlogic > .specification

cheers,

Get Session Data Available in Models - Ruby on Rails

noreply@blogger.com (Chirag Shah) — Thu, 24 Jun 2010 00:16:38 PDT

Sometimes we really need session variables inside model. But as the rails framework defines (MVC) pattern.

This pattern separates the context of the Web Application (Controller,View) from the Model. Model contains business logic of the web application. The Controller handles the interactions between the View and the Model.

So you can not access sessions directly in your model. You can crack it by following way.

Create one module

module Utility
  def current_user
    Thread.current[:user]
  end
 
  def self.current_user=(user)
    Thread.current[:user] = user
  end
end

Add following in application controller

class ApplicationController < ActionController::Base
  include Utility
  before_filter :set_user_session
 
  protected
  def set_user_session
    Utility.current_user = session[:user]
  end
end

And now get it in your model

class Account < ActiveRecord::Base
  include Utility

  def before_create
    unless allowed?(current_user)

      return false

    end
  end
end

fetch all controllers and actions of the application

noreply@blogger.com (Chirag Shah) — Thu, 24 Jun 2010 00:30:11 PDT

dirs = Dir.new("#{RAILS_ROOT}/app/controllers").entries

controller_hash = {}

dirs.each do |controller|

if controller =~ /_controller/

path = RAILS_ROOT + '/app/controllers/' + controller

con = File.read(path).split('def ')

con.delete_at(0)

my_hash = Hash.new

actions = con.collect{|c| c.gsub("\r","~").gsub("\n","~").split("~")[0].strip}

controller_name = controller.gsub('.rb','')

my_hash = {controller_name.to_s => actions}

controller_hash = my_hash.merge(controller_hash)

end

puts controller_hash.inspect

How to generate an SSH key in Linux?

noreply@blogger.com (Chirag Shah) — Fri, 05 Feb 2010 04:33:14 PST

You can generate a key in Linux using the ssh-keygen command.
You can run it in command line. You will be asked for a file in which the key should be saved to and for a passphrase (password) for the key:
This command will generate id_rsa public and private keys.

If you need to generate id_dsa keys then you need to run ssh-keygen -t dsa

cannot open shared object file: No such file or directory

noreply@blogger.com (Chirag Shah) — Thu, 24 Jun 2010 00:31:24 PDT

I got below error while i tried to run my application in fedora

libMagickCore.so.2: cannot open shared object file: No such file or directory – /usr/lib/ruby/gems/1.8/gems/rmagick-2.8.0/lib/RMagick2.so

To get solved of this error i executed

ldconfig /usr/local/lib

Use of Dirty Objects

noreply@blogger.com (Chirag Shah) — Tue, 17 Nov 2009 01:50:45 PST

Uses of Dirty Objects

Developer have some confusion that how they can get the previous value of the field after update.
So here the rails has a way called Dirty objects.

You can found Module Dirty in rails/activerecord/lib/active_record/dirty.rb
This is just for track unsaved attribute changes.
There are few methods in dirty module as below
* Changed
* Changed?
* Changes
* Included
And it has some constants

DIRTY_SUFFIXES = ['_changed?', '_change', '_will_change!', '_was']

book = Book.find(1)

book.name = 'agiles'
book.changed? # => true
book.name_changed? # => true
book.name_was # => 'rails startup'
book.name_change # => ['rails startup', 'agiles']
book.name = 'agiles with rails'
book.name_change # => ['rails startup', 'agiles with rails']

You can found the details in http://api.rubyonrails.org/classes/ActiveRecord/Dirty.html

Remove .svn files / folders

noreply@blogger.com (Chirag Shah) — Mon, 22 Jun 2009 23:26:42 PDT

I have found from some where to use the below syntax for remove .svn folders. And it works for me so i thought it might be useful. So i shared this

find ./ -name ".svn" | xargs rm -Rf

or

find ./ -name “.svn” -exec rm -rf {} \;

Source: http://www.rickhurst.co.uk/category/linux/

Receive Mail with attachment using TMail - Ruby on Rails

noreply@blogger.com (Chirag Shah) — Sun, 19 Apr 2009 23:58:32 PDT

Receive Mails using TMail. I like to use TMail for receive mail because TMail is best to handle the header of the email object. There are only a few methods that deal directly with the body of the email. So i just thought to share it. I have used pop3 for receive mail and use TMail for parse it.
For use TMail you need to do install gem.

gem install TMail

def popmail
     require 'net/pop'
     require 'tmail_mail_extension.rb'

     pop = Net::POP3.new 'mail.example.com'
     pop.start 'test-receive@example.com', 'password'

     if pop.mails.empty?
       puts 'No mail.'
     else
       pop.each_mail do |mail|
        email = TMail::Mail.parse(mail.pop)
        subject = email.subject
        from_email = email.from
        body = email.body_html
        if email.has_attachments?
        email.parts.each_with_index do |part, index|
          filename = part_filename(part)
          content_type = part.content_type
          filename ||= "#{index}.#{ext(part)}"
          file = filename
          fname = file.split(".")
          newfilename = fname[0]+'_'+(Time.now.to_i).to_s+'.'+fname[1]
          filepath = "#{RAILS_ROOT}/public/file_attachement/#{newfilename}"
          File.open(filepath,'wb'){|f| f.write(part.body)}
          filesize= File.size(filepath)
        end
      end
       # Do your Logic after getting details
     mail.delete
     end
   pop.finish
end

def part_filename(part)
     file_name = (part['content-location'] &&
     part['content-location'].body) ||
     part.sub_header("content-type", "name") ||
     part.sub_header("content-disposition", "filename")
end

CTYPE_TO_EXT = {
     'image/jpeg' => 'jpg',
     'image/gif' => 'gif',
     'image/png' => 'png',
     'image/tiff' => 'tif'
}

def ext( mail )
     CTYPE_TO_EXT[mail.content_type] || 'txt'
end

Note: You can get body part of email by email.body and no need to use of tmail_mail_extension.rb

But it gives your body part two times. one in normal text of body and second is html of the same body. If you want only html of the body then you need tmail_mail_extension.rb. I found that logic of tmail_mail_extension.rb file from somewhere, i forgot the link for that.
But you can write below which i found from somewhere. Write below code in tmail_mail_extention.rb

tmail_mail_extention.rb
module TMail
   class Mail

   # returs an String with just the html part of the body
   # or nil if there is not any html part

   def body_html
     result = nil
     if multipart?
       parts.each do |part|
         if part.multipart?
          part.parts.each do |part2|
          result = part2.unquoted_body if part2.content_type =~ /html/i
          end
         elsif !attachment?(part)
          result = part.unquoted_body if part.content_type =~ /html/i
         end
       end
     else
       result = unquoted_body if content_type =~ /html/i
     end
     result
   end

   def parts_observer
     puts "INI"
     puts "content_type: #{content_type}"
     puts "body: #{body}"
     puts "parts.size: #{parts.size}"

     if multipart?
       parts.each_with_index do |part, index|
       puts ""
       puts " parts[#{index}]"
       puts " content_type: #{part.content_type}"
       puts " multipart? #{part.multipart?}"

       header = part["content-type"]

       if part.multipart?
         puts " --multipartt--"
         part.parts.each_with_index do |part2, index2|
          puts " part[#{index}][#{index2}]"
          puts " content_type: #{part2.content_type}"
          puts " body: #{part2.unquoted_body}"
         end
       elsif header.nil?
         puts " --header nil--"
     elsif !attachment?(part)
       puts " --no multipart, no header nil, no attachment--"
       puts " content_type: #{part.content_type}"
       puts " body: #{part.unquoted_body}"
     else
       puts " --no multipart, no header nil, attachment--"
       puts " content_type: #{part.content_type}"
     end

     end
     else
       puts " --no multipart--"
       puts " content_type: #{content_type}"
       puts " body: #{unquoted_body}"
     end

     puts "END"
   end

   end
end

Merb gets merged into Rails 3.0 !!

noreply@blogger.com (Chirag Shah) — Mon, 26 Jan 2009 06:03:37 PST

Ruby on Rails team broke the news: the alternative Ruby web application framework, Merb, will be merged into Ruby on Rails 3.0.

Merb, which was already closely patterned after Rails, brings performance, modularity, and better integration with alternative JavaScript and ORM frameworks to the table. The default Rails configuration will still be the "full stack" framework, which uses ActiveRecord and Prototype, but there will also be a "Rails Core" with the ability to opt into specific other (e.g. JavaScript or ORM) frameworks as desired.

The Merb team will be working with the Rails core team on a joint project. The plan is to merge in the things that made Merb different. This will make it possible to use Rails 3 for the same sorts of use-cases that were compelling for Merb users. Effectively, Merb 2 is Rails 3.

You can read more about here:

Inline file upload - iframe - ajax - Ruby on Rails

noreply@blogger.com (Chirag Shah) — Fri, 23 Jan 2009 23:47:50 PST

In View

<% form_for(@images, :url => formatted_images_path(:format => 'js'), :html => { :multipart => true,:target => 'upload_frame' }) do |f| %>
Image
<%= f.file_field :uploaded_data, :size => "50" %>
<%= f.submit :Submit %>
<% end %>
< id="'upload_frame'," name="upload_frame" style="width:1px;height:1px;border:0px" src = "about:blank">

in controller
def create
@image = Image.new
if @image.save
respond_to do |format|
format.js do
responds_to_parent do
render :update do |page|
page.replace_html 'imgupload', :partial => 'imageupload',:object => @images
page.visual_effect :highlight, "image_#{@image.id}"
end
end
end
end
end
end

Watermarking an image in Rails - Rmagick

noreply@blogger.com (Chirag Shah) — Fri, 23 Jan 2009 23:04:32 PST

class Image < ActiveRecord::Base

require 'RMagick'
has_attachment :content_type => :image,
:storage => :file_system,
:max_size => 4.megabytes,
:resize_to => '640x400>',
:thumbnails => { :thumb => '100x100>',:medium => '250x150' }

validates_as_attachment

def watermark_image
dst = Magick::Image.read("#{RAILS_ROOT}/public/#{self.public_filename}").first
src = Magick::Image.read("#{RAILS_ROOT}/public/images/logo.gif").first
result = dst.composite(src, Magick::CenterGravity, Magick::HardLightCompositeOp)
result.write("#{RAILS_ROOT}/public/#{self.public_filename}")
end

Improving Rails Applications performance

noreply@blogger.com (Chirag Shah) — Fri, 23 Jan 2009 21:45:27 PST

I have done some research about improving Rails Applications performance. I would feel the the following few points need to be considered when we optimize rails applications for performance:

1) Avoid the use of dynamic URL generation (link_to, url_for) since rails needs to look up the routes table and that may take time. Just hard code the controller name and the action.

2) Try to avoid the excess use of helpers since it adds overhead.

3) You may consider to use Rails Bench to do some testing for you rails application performance.

4) You may consider to use memcached to cache your model and library computation results.

5) try to optimize your database queries. If you use ActiveRecord find, be careful from computation intensive sql queries that returns to you a lot of data that you may not need. The method find may run many select statements for you.

observe_field Example - Ruby on Rails

noreply@blogger.com (Chirag Shah) — Wed, 24 Sep 2008 05:40:20 PDT

<table>
<tr>
<td><label for="searchtext"><font size="1"><b>Live Book Search:</b></font></label></td>
<td><%= text_field_tag :searchtext %></td>
<td><img alt="spinner" id="spinner" src="/images/spinner.gif" style="display:none;" /></td>
</tr>
</table>

<%= observe_field 'searchtext', :frequency => 0.5,
:update => 'search_hits',
:loading => "Element.show('spinner')",
:complete => "Element.hide('spinner')",
:url => { :controller => 'books', :action=> 'live_search' },
:with => "'search=' + escape(value)" %>

<div id="search_hits">
<table>
<tr>
<th>Name</th>
<th>Author</th>
<th>Price</th>
<th>Desc</th>
</tr>

<% for book in @books %>
<tr>
<td><%=h book.name %></td>
<td><%=h book.author %></td>
<td><%=h book.price %></td>
<td><%=h book.desc %></td>
<td><%= link_to 'Show', book %></td>
<td><%= link_to 'Edit', edit_book_path(book) %></td>
<td><%= link_to 'Destroy', book, :confirm => 'Are you sure?', :method => :delete %></td>
</tr>
<% end %>
</table>

For more detail go to
Wiki.rubyonrails.org

Variables In Request Env - Ruby on Rails

noreply@blogger.com (Chirag Shah) — Wed, 24 Sep 2008 05:18:04 PDT

request.env is a Ruby Array that contains information about a visiting user’s and server environments.
request.env is accessible on all pages hosted in a ruby on rails site. The Array contains the following key/value pairs:

SERVER_NAME
PATH_INFO
REMOTE_HOST
HTTP_ACCEPT_ENCODING
HTTP_USER_AGENT
SERVER_PROTOCOL
HTTP_CACHE_CONTROL
HTTP_ACCEPT_LANGUAGE
HTTP_HOST
REMOTE_ADDR
SERVER_SOFTWARE
HTTP_KEEP_ALIVE
HTTP_REFERER
HTTP_COOKIE
HTTP_ACCEPT_CHARSET
REQUEST_URI
SERVER_PORT
GATEWAY_INTERFACE
QUERY_STRING
REMOTE_USER
HTTP_ACCEPT
REQUEST_METHOD
HTTP_CONNECTION

For testing purposes it might be useful to print out a table with the request.env information in it.

<table>
<th>key</th>
<th>Value</th>
<% for item in request.env %>
<tr>
<td><%= item[0] %></td>
<td><%= item[1] %></td>
</tr>
<% end %>
</table>

Installing Rmagick on Windows Using Ruby 1.8.6

noreply@blogger.com (Chirag Shah) — Wed, 24 Sep 2008 05:03:27 PDT

Rmagick tends to be tricky to install, but on windows its relatively simple, except for the fact that if you freshly installed ruby 1.8.6, ruby gems needs to be updated. If you install ruby 1.8.6 and then go to ruby.forge and download rmagick for windows. Extract the zip folder, run the .exe, then open a command line, cd (change directory) to the install folder and do “gem install rmagick —local”. The first time you do this, you might run into the “Error installing gem RMagick (version) .gem[.gem]: buffer error”. To fix that run “gem update —system” with double hyphens and then run “gem install rmagick —local” and everything should now install fine.

Dynamically add and remove html elements using javascript

noreply@blogger.com (Chirag Shah) — Wed, 24 Sep 2008 04:56:19 PDT

<input type="hidden" value="0" id="theValue" />
<p><a href="javascript:;" onclick="addElement();">Add Some Elements</a></p>
<div id="myDiv"> </div>

<script>
function addElement() {
var ni = document.getElementById('myDiv');
var numi = document.getElementById('theValue');
var num = (document.getElementById('theValue').value -1)+ 2;
numi.value = num;
var newdiv = document.createElement('div');
var divIdName = 'my'+num+'Div';
newdiv.setAttribute('id',divIdName);
newdiv.innerHTML = 'Element Number '+num+' has been added! <a href=\'#\' onclick=\'removeElement('+divIdName+')\'>Remove the div "'+divIdName+'"</a>';
ni.appendChild(newdiv);
}

function removeElement(divNum) {
var d = document.getElementById('myDiv');
var olddiv = document.getElementById(divNum);
d.removeChild(olddiv);
}
</script>

NAMED_SCOPE in Ruby on Rails

noreply@blogger.com (Chirag Shah) — Mon, 25 Aug 2008 21:29:04 PDT

The has_finder gem has been added to Rails with a different name: named_scope

For better understand let go through the following example:

class Article < ActiveRecord :: Base
named_scope :published, :conditions => {:published => true}
named_scope :containing_the_letter_c, :conditions => "author LIKE '%c%’"
end

Article.published.paginate(:page => 1)
Article.published.containing_the_letter_c.count
Article.containing_the_letter_c.find(:first)

Instead of creating a new method named published to return all published posts, I'm using a named_scope to do it for me.
But it can go even further than this. Let's look at another example of how it can be used:

named_scope :written_before, lambda { |time|
{ :conditions => ['written_on < ?', time] }
}