Using Regular Expression in Ruby on Rails — Regexp for Password Validation
A regular expression (abbreviated as regexp or regex, with plural forms regexps, regexes, or regexen) is a string that describes or matches a set of strings, according to certain syntax rules. Regular expressions are used by many text editors and utilities to search and manipulate bodies of text based on certain patterns. Many programming languages support regular expressions for string manipulation. Ruby has a strong Regular Expression engine built directly as a class of Ruby Programming language as Regexp
Here we will go through an example which will validate the password string.
Lets say we have to implement the following validations to validate a password…
- Password should contain atleast one integer.
- Password should contain atleast one alphabet(either in downcase or upcase).
- Password can have special characters from 20 to 7E ascii values.
- Password should be minimum of 8 and maximum of 40 cahracters long.
To fulfill above requirements we can have a regular expression like…
/^(?=.*\d)(?=.*([a-z]|[A-Z]))([\x20-\x7E]){8,40}$/
in ruby programming language we can have a number of ways to define this regular expression as…
■ reg = Regexp.new(“^(?=.*\d)(?=.*([a-z]|[A-Z]))([\x20-\x7E]){8,40}$”)
or
■ reg = %r(^(?=.*\d)(?=.*([a-z]|[A-Z]))([\x20-\x7E]){8,40}$)
or simply
■ reg = /^(?=.*\d)(?=.*([a-z]|[A-Z]))([\x20-\x7E]){8,40}$/
Now look what exactly this regex is doing…
(?=.*\d) shows that the string should contain atleast one integer.
(?=.*([a-z]|[A-Z])) shows that the string should contain atleast one alphabet either from downcase or upcase.
([\x20-\x7E]) shows that string can have special characters of ascii values 20 to 7E.
{8,40} shows that string should be minimum of 8 to maximum of 40 cahracters long.
We can simply use this regular expression for manual handling of password in an action as…
def validate_password(password)
reg = /^(?=.*\d)(?=.*([a-z]|[A-Z]))([\x20-\x7E]){8,40}$/
return (reg.match(password))? true : false
end
How to implement this regular expression in a model class in ruby on rails for password validation ?
To implement this regular expression in the model class in the rails way we can do it like…
class MyModel
validates_format_of :password, :with => /^(?=.*\d)(?=.*([a-z]|[A-Z]))([\x20-\x7E]){8,40}$/
end
4 comments October 19, 2006
Rake task to prepare test database from migrations
To use your migrations for preparing test database create a file testdb.rake
in the directory lib/tasks.
Now add the following code in the lib/tasks/testdb.rake file…
module Rake
module TaskManager
def redefine_task(task_class, args, &block)
task_name, deps = resolve_args(args)
task_name = task_class.scope_name(@scope, task_name)
deps = [deps] unless deps.respond_to?(:to_ary)
deps = deps.collect {|d| d.to_s }
task = @tasks[task_name.to_s] = task_class.new(task_name, self)
task.application = self
task.add_comment(@last_comment)
@last_comment = nil
task.enhance(deps, &block)
task
end
end
class Task
class << self
def redefine_task(args, &block)
Rake.application.redefine_task(self, args, &block)
end
end
end
end
def redefine_task(args, &block)
Rake::Task.redefine_task(args, &block)
end
namespace :db do
namespace :test do
desc 'Prepare the test database and migrate schema'
redefine_task :prepare => :environment do
Rake::Task['db:test:migrate_schema'].invoke
end
desc 'Use the migrations to create the test database'
task :migrate_schema => 'db:test:purge' do
ActiveRecord::Base.establish_connection(ActiveRecord::Base.configurations['test'])
ActiveRecord::Migrator.migrate("db/migrate/")
end
end
end
To prepare the test database from migrations run this command
$ rake db:test:migrate_schema
3 comments October 17, 2006
How to improve the image quality and generate random string image in the plugin validates_captcha
Hello Everyone !!
I have released a captcha plugin Simple Captcha. It is really simple to implement, and provides a cool feature of multiple styles of images.
Previous post about improving validates_captcha’s images
Validates captcha is a good plugin to implement captcha in your rails application.
However i found that there is repetition of the string of the image and the quality of image is not that good. To get a good quality image and random string
something like this
replace the code of the file /vendor/plugins/validates_captcha/lib/captcha_challenge.rb with the following code…
require 'digest/sha1'
module AngryMidgetPluginsInc #:nodoc:
# CaptchaChallenge
class CaptchaChallenge
include CaptchaConfig
extend CaptchaConfig
DEFAULT_TTL = 1200#Lifetime in seconds. Default is 20 minutes.
attr_reader :id, :created_at
attr_accessor :ttl
def initialize(options = {}) #:nodoc:
generate_id
options = {
:ttl => config['default_ttl'] || DEFAULT_TTL
}.update(options)
self.ttl = options[:ttl]
@created_at = Time.now
self.class.prune
end
# Implement in subclasses.
def correct? #:nodoc:
raise NotImplementedError
end
private
def generate_id #:nodoc:
self.id = Digest::SHA1.hexdigest(Time.now.to_s+rand.to_s)
end
def id=(i) #:nodoc:
@id = i
end
def write_to_store #:nodoc:
store.transaction{
store[:captchas] = Array.new unless store.root?(:captchas)
store[:captchas] << self
}
end
class << self
# Removes old instances from PStore
def prune
store.transaction{
if store.root?(:captchas)
store[:captchas].each_with_index{|c,i|
if Time.now > c.created_at+c.ttl
store[:captchas].delete_at(i)
end
}
end
}
end#prune
end#class << self
end
# A CAPTCHA challenge where an image with text is
# generated. A human can read the text with relative
# ease, while most robots can not. There are accessibility
# problems with this challenge, though, as people
# with reduced or no vision are unlikely to pass the test.
class CaptchaImageChallenge < CaptchaChallenge
WORDS = 'gorilla costume, superman, banana bender, chuck norris, xray vision, ahoy me hearties,
chunky bacon, latex, rupert murdoch, clap your hands, year 2000,
sugar coated, coca cola, rastafarian, airbus a380'.split(/,s+/)
DEFAULT_DIR = 'captcha'#public/images/captcha
WRITE_DIR = File.join(RAILS_ROOT, 'public', 'images')
DEFAULT_FILETYPE = 'jpg'
attr_reader :image
attr_accessor :string, :dir, :filename, :filetype
# Creates an image challenge.
def initialize(options = {})
super
options = {
:string => config['words'] ? config['words'][rand(config['words'].size)] : WORDS[rand(WORDS.size)],
:dir => config['default_dir'] || DEFAULT_DIR,
:filetype => config['default_filetype'] || DEFAULT_FILETYPE
}.update(options)
self.string = Digest::SHA1.hexdigest(Time.now.to_s)[0..4].upcase #options[:string]
self.dir = options[:dir]
self.filetype = options[:filetype]
self.filename = options[:filename] || generate_filename
write_to_store
end
# Generates the image.
def generate(options = {})
options = {
:fontsize => 50,
:padding => 20,
:color => '#000',
:background => '#fff',
:fontweight => 'bolw',
:rotate => true
}.update(options)
options[:fontweight] = case options[:fontweight]
when 'bold' then 700
else 400
end
#added
text = Array.new
0.upto(4) do |i|
text[i] = Magick::Draw.new
text[i].pointsize = options[:fontsize]
text[i].font_weight = 600 #options[:fontweight]
text[i].fill = 'black' #options[:color]
text[i].gravity = Magick::CenterGravity
text[i].rotation = (rand(2)==1 ? rand(30) : -rand(30)) if options[:rotate]
end
metric = text[2].get_type_metrics(self.string)
#add bg
canvas = Magick::ImageList.new
fill = Magick::HatchFill.new('white','black')
x = metric.width+options[:padding]
y = metric.height+options[:padding]
#ADDING NOISE
img1 = Magick::Image.new(x,y,fill)
gc = Magick::Draw.new
gc.stroke_linejoin('round')
gc.stroke('black')
gc.stroke_width(1)
100.times do |i|
x1 = rand(x)
y1 = rand(y)
gc.circle(x1,y1,x1.next,y1)
end
gc.draw(img1)
canvas << img1
0.upto(4) do |i|
canvas << Magick::Image.new(metric.width+options[:padding], metric.height+options[:padding]){
self.background_color = '#000F'
y_loc = rand(y)
}.annotate(text[i], 0, 0, (i-2)*30, rand(y/4), self.string[i,1]) #.wave(5, 20)
end
canvas << Magick::Image.new(metric.width+options[:padding], metric.height+options[:padding]){
#changed
p = Magick::Pixel.from_color(options[:background])
p.opacity = Magick::MaxRGB
self.background_color = p
} #.add_noise(Magick::LaplacianNoise)
self.image = canvas.flatten_images.blur_image(1)
end
# Writes image to file.
def write(dir = self.dir, filename = self.filename)
self.image.write(File.join(WRITE_DIR, dir, filename))
end
# Determine if the supplied +string+ matches
# that used when generating the image.
def correct?(string)
string.downcase == self.string.downcase
end
# The full path to the image file, relative
# to <tt>public/images</tt>.
def file_path
File.join(dir,filename)
end
class << self
# Deletes old image files. Also calls CaptchaChallenge.prune
def prune
store.transaction{
if store.root?(:captchas)
store[:captchas].each_with_index{|c,i|
if Time.now > c.created_at+c.ttl
if File.exists?(File.join(WRITE_DIR, c.file_path))
begin
File.unlink(File.join(WRITE_DIR, c.file_path))
rescue Exception
end
end
end
}
end
}
super
end#prune
end#class << self
private
def generate_filename #:nodoc:
self.id+'.'+self.filetype
end
def image=(i) #:nodoc:
@image = i
end
end
end
visit Here to view the customized use of the plugin validates_captcha in RoR.
22 comments October 17, 2006
Rake task to remove the image and audio files created by captcha
To add a rake task to the rails application which removes all the image and audio files created by captcha, create a file named remove_captcha_files.rake in the lib/tasks directory.
Add the following code to the lib/tasks/remove_captcha_files.rake file…
desc "Remove captcha images and audio files"
task :remove_captcha_files do
image_path = "#{RAILS_ROOT}/public/images/captcha/"
audio_path = "#{RAILS_ROOT}/public/captcha_audio/"
Dir.foreach(image_path){|file| File.delete(image_path+file) if (/^.*.jpg$/).match(file)} if File.exist?(image_path)
Dir.foreach(audio_path){|file| File.delete(audio_path+file) if (/^.*.wav$/).match(file)} if File.exist?(audio_path)
puts "Captcha files removed."
end
You can confirm that task is added to your app by running
rake –task
To remove all the files created by captcha, simply run the command
rake remove_captcha_files
from the command line from your application root.
To better view the code visit here
Add comment October 16, 2006
Translate Your Rails Application.
Gettext is a great tool for translating user interfaces of applications into different languages. It has been around for a long time and is very well established for this task. Gettext helps you to open up your application for a much wider user base than you would normaly reach with only one language. Since it is used in many open source projects it has a lot of useful tools you can use to your own advantage. It would be possible to “roll your own” solution, but this would consume a large amount of time. Time you would lose for the development of your app. And this is not something you would want, right?
So in this tutorial I am going to show you how to effectively use Gettext for all your translation needs in your Ruby on Rails application.
What can Gettext do for you?
Here is a quick explanation of Gettext for those of you who haven’t worked with it, yet. Gettext is a set of tools that provide help when translating strings in your software. It gives you (straight from the gettext manual):
- A set of conventions about how programs should be written to support message catalogs.
- A directory and file naming organization for the message catalogs themselves.
- A runtime library supporting the retrieval of translated messages.
- A few stand-alone programs to massage in various ways the sets of translatable strings, or already translated strings.
The only thing you have to do to your program sources is wrap all translatable strings with a method call: gettext(text) or shorter _(text). Example:
Without gettext:
notice = 'Thank you for buying our product.'
With gettext:
notice = _('Thank you for buying our product.')
For more details check this out
GetText on Rails
Add comment September 6, 2006
Source Code For Ajax Based Drag Drop Navigation Tree in Ruby on Rails – the tree works well with firefox and IE-6
Ajaxified Drag Drop Tree in RoR
CASE STUDY
I m providing a very generalized use case where the tree fits in a good position. Here it is…
Consider a model Item, a controller Items. Item model is using a fabulous acts_as_tree and we are going to put a seed for Item to grow it in an ajax tree 
… Ok no more non-code talk. So, lets start the code now…
==========================================================
I have also incorporated the code into a sample application which you can directly check out and try the tree yourself if you find it a
headache to add the following code in a number of described files.
So, here is the Sample Tree Application
or you can try to code yourself as…
Create a sample rails application say treeapp by running
rails treeapp
from the command prompt.
Now simply change your directiry into just created treeapp and make sure that you are in the directory treeapp
Now configure the database settings for this application by modifying the file /config/database.yml as …
development: adapter: mysql database: tree_dev username: root password: root host: localhost
Here it simply shows that you have a mysql database named tree_dev and a user root with password root can access this database. So make sure about these settings.
From the command prompt in application root(i.e. you are in the directory treeapp) run this command to generate the model Item…
treeapp> ruby script/generate model item
Add the following code to the file app/models/itme.rb
class Item < ActiveRecord::Base
acts_as_tree
validates_presence_of :name
attr_accessor :style
def self.roots
self.find(:all, :conditions=>["parent_id = ?", 0])
end
def level
self.ancestors.size
end
end
This simply shows that you should have a table named tems in your database…
so why we havnt mentioned it earlier ?
Thats the thing which will make you feel an agile web development.
Now look at the directory db/migrateand a you will find a file named as db/migrate/001_create_items.rb
Add the following code to this file 001_create_items.rb
Here we are creating our database table and also adding some initial data to work with.
class CreateItems < ActiveRecord::Migration
def self.up
create_table "items", :force => true do |t|
t.column "name", :string
t.column "created_at", :datetime
t.column "parent_id", :integer, :default => 0, :null => false
end
%w(item1 item2 item3 item4 item5).each do |name|
parent = Item.new(:name=>name)
parent.save
Item.create(:name=>name+".1", :parent_id=>parent.id)
Item.create(:name=>name+".2", :parent_id=>parent.id)
Item.create(:name=>name+".3", :parent_id=>parent.id)
end
end
def self.down
drop_table :items
end
end
Now from the command line from the root of your application run the following command to have a table named Item in your database with some initial data.
treeapp> rake db:migrate
Before we start handling our views and controller part just have a smart small image named as drag.gif in your public/images directory that we will use as a handle to drag the nodes. So, now you can see a small image at public/images/drag.gif, cool !.
Now from the command line from the root of your application run the following command to create a controller …
treeapp> ruby script/generate controller items show
Make sure that now you have the files app/controllers/items_controller.rb and app/views/items/show.rhtml.
Add the following code in the file app/controllers/items_controller.rb
class ItemsController < ApplicationController
def show
@items = Item.find(:all)
@item = Item.find(:first)
# select according to your choice...
#this item will be selected node by default in the tree when it will first be loaded.
end
def display_clicked_item
# this action will handle the two way syncronization...all the tree nodes(items) will be linked
# to this action to show the detailed item on the left of the tree when the item is clicked
# from the tree
if request.xhr?
@item = Item.find(params[:id]) rescue nil
if @item
# the code below will render all your RJS code inline and
# u need not to have any .rjs file, isnt this interesting
render :update do |page|
page.hide "selected_item"
page.replace_html "selected_item", :partial=>"items/item", 
bject=>@item
page.visual_effect 'toggle_appear', "selected_item"
end
else
return render :nothing => true
end
end
end
def sort_ajax_tree
if request.xhr?
if @item = Item.find(params[:id].split("_").first) rescue nil
parent_item = Item.find(params[:parent_id])
render :update do |page|
@item.parent_id = parent_item.id
@item.save
@items=Item.find(:all)
page.replace_html "ajaxtree", :partial=>"items/ajax_tree", bject=>[@item,@items]
page.hide "selected_item"
page.replace_html "selected_item", :partial=>"items/item", bject=>@item
page.visual_effect 'toggle_appear', "selected_item"
end
else
return render :nothing => true
end
end
end
end
Add the following code in the file app/views/items/show.rhtml
<h2>Ajax Tree Application</h2> <div id="ajaxtree" style="width:40%;float:left;"> <%= render :partial=>'items/ajax_tree',
Add the following code in the file app/views/items/_item.rhtml
<% if @item %> <h2>Selected Item is <%=h @item.name%> </h2> <% else %> Item not found <% end %>
Add the following code in the file app/views/items/_ajax_tree.rhtml
<script type="text/javascript">
function toggleDiv()
{
Element.toggle('mytree');
Element.toggle('expanded');
Element.toggle('collapsed');
return false;
}
function showDrag()
{
var drag_images = $$('img.drag_image');
drag_images.all(function(value,index){return value.style.display='inline';});
Element.toggle('done');
Element.toggle('reorder');
return false;
}
function hideDrag()
{
var drag_images = $$('img.drag_image');
drag_images.all(function(value,index){return value.style.display='none';});
Element.toggle('done');
Element.toggle('reorder');
return false;
}
</script>
<style>
.mytree{padding:0 0 0 0px;}
.mytree li {padding:2 0 0 3px;}
.outer_tree_element{margin:0 0 0 10px;}
.inner_tree_element{margin:5px 0 0 10px;}
.mytree a{text-decoration:none; font-size:13px; color:black;}
.mytree a:hover{background-color:lightblue;}
.mytree label{font-weight:normal;}
.highlighted{background-color:lightblue;}
.normal{background-color:white;}
.drag_image{border:0px;}
</style>
<div id="mytree" class="mytree">
<% @ancestors = @item.ancestors.collect{|parent| parent.id} if @item.has_parent? %>
<% @items = Item.find(:all) %>
<%= get_tree_data(@items, 0){|n|
link_to_remote(n.name,
:url=>{:controller=>'items', :action=>'display_clicked_item', :id=>n.id},
:loading=>"Element.show('tree_indicator')",
:complete=>"Element.hide('tree_indicator')"
)}
%>
<% @items.each do |node| %>
<%= draggable_element node.id.to_s+'_tree_div',:revert=>true,:snap=>false, :handle=>"'#{node.id.to_s}_drag_image'" %>
<%= drop_receiving_element node.id.to_s+'_tree_div',
:accept=>'inner_tree_element',
:url=>{:controller=>'items',:action=>'sort_ajax_tree', :parent_id=>node.id,:id=>nil},
:loading=>"Element.show('sort_tree_indicator')",
:complete=>"Element.hide('sort_tree_indicator')"
%>
<% end %>
<%= image_tag 'indicator.gif', :id=>'tree_indicator', :style=>'display:none' %>
<%= image_tag 'indicator.gif', :id=>'sort_tree_indicator', :style=>'display:none' %>
</div>
<script type="text/javascript">
var selected_el = document.getElementById('<%=@item.id%>_tree_item');
selected_el.className='highlighted';
function toggleMyTree(id)
{
Element.toggle(id+'collapsed');
Element.toggle(id+'expanded');
Element.toggle(id+'children');
return false;
}
function toggleBackground(el)
{
// using collection proxies to change the background
var highlighted_el = $$("span.highlighted");
highlighted_el.all(function(value,index){return value.className='normal'});
el.className='highlighted';
selected_el = el;
return false;
}
function openMyTree(id)
{
Element.hide(id+'collapsed');
Element.show(id+'expanded');
Element.show(id+'children');
return false;
}
</script>
As you can see in the above file we have used some indicator and toggle images. So you will be required to have three more images in the directory public/images/.
Here is the small description about these images…
- An indicator image that will be displayed at the bottom of the tree whenever a tree node is clicked. You can select from a number of Ajax Inidicatorsavailable on the web. Select one indicator image and save in your app with the name indicator.gif. So, now make sure that you can see the image at public/images/indicator.gif
- Second, we need to have a small image with + sign. That will be used to toggle the tree. save it as public/images/collapsed.gif
- Similarly, an image with - sign. Save it as public/images/expanded.gif
We have to include the prototype and scriptaculous javascript libraries in the application.
So just manually create a layout file app/views/layouts/application.rhtml and add the following code in the file application.rhtml
<html>
<head>
<%= javascript_include_tag :defaults %>
</head>
<body>
<%= @content_for_layout %>
</body>
</html>
Now the last but the most importatnt…The recursion to obtain the tree.
Add the following code in the file app/helpers/application_helper.rb
module ApplicationHelper
def get_tree_data(tree, parent_id)
ret = "<div class='outer_tree_element' >"
tree.each do |node|
if node.parent_id == parent_id
node.style = (@ancestors and @ancestors.include?(node.id))? 'display:inline' : 'display:none'
display_expanded = (@ancestors and @ancestors.include?(node.id))? 'inline' : 'none'
display_collapsed = (@ancestors and @ancestors.include?(node.id))? 'none' : 'inline'
ret += "<div class='inner_tree_element' id='#{node.id}_tree_div'>"
if node.has_children?
ret += "<img id='#{node.id.to_s}expanded' src='/images/expanded.gif' onclick='javascript: return toggleMyTree(\"#{node.id}\"); ' style='display:#{display_expanded}; cursor:pointer;' /> "
ret += "<img style='display:#{display_collapsed}; cursor:pointer;' id='#{node.id.to_s}collapsed' src='/images/collapsed.gif' onclick='javascript: return toggleMyTree(\"#{node.id.to_s}\"); ' /> "
end
ret += " <img src='/images/drag.gif' style='cursor:move' id='#{node.id}_drag_image' align='absmiddle' class='drag_image' /> "
ret += "<span id='#{node.id}_tree_item'>"
ret += yield node
ret += "</span>"
ret += "<span id='#{node.id}children' style='#{node.style}' >"
ret += get_tree_data(node.children, node.id){|n| yield n}
ret += "</span>"
ret += "</div>"
end
end
ret += "</div>"
return ret
end
end
Now you can check the tree functionality at http://localhost:3000/items/show.. assuming that you are running your server on port 3000. njoy!!
28 comments August 18, 2006
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