Today, I have started testing Beta release of Rails 3.0.By Default Rails 3.0 start with webrick.To start with mongrel do following steps.
1)Install mongrel gem
sudo gem install mongrel
2) After installing mongrel gem go to config/boot.rb file
and add following line
require "mongrel"
3) Start server as rails server
There are various ways to generate pdf documents in any language.In Rails we can use prawn library ,HtmlDoc,PrinceXml and many other library,using their api we can generate pdf document.Basically the primary goal is converting HTML web pages to PDF Document,without much changing existing CSS and HTML.
Using the Flying Saucer Project we can achieve this.we can convert HTML + CSS to PDF documents without much changing HTML and CSS. It also support CSS 2 and many properties of CSS 3 for printing Header,Footer,Page Number,Paginated Tables and many more.This Project is built on Java so Java is required on system.
Lets Start How to generate PDF Using Flying Saucer.
script/plugin install git://github.com/amardaxini/acts_as_flying_saucer.git
This Plugin forked From
http://github.com/dagi3d/acts_as_flying_saucer
Which has older version of flying saucer project.
Next Step after installing plugin add flying_saucer.rb file at config/initializers.
ActsAsFlyingSaucer::Config.options = {
:java_bin => "/usr/bin/java", # java binary
:classpath_separator => ':', # classpath separator. unixes system use ':' and windows ';'
:tmp_path => "/tmp", # path where temporary files will be stored
}
After Setting Java path , classpath separator and tmp path now do following step.
class PdfController < ActionController::Base
acts_as_flying_saucer
def generate_pdf
render_pdf :template => 'pdf/pdf_template'
end
end
render_pdf :file=>'pdf/generate_pdf.html.erb'
render_pdf :template=>'pdf/generate_pdf.pdf.erb',
:send_file => { :filename => 'pdfdoc.pdf' }
Add act_as_flying_saucer to controller then render_pdf.There are various ways to render pdf using “template” or “file“,:send_file option use to send pdf file to client side.if we are using any external css file then this css shoulda have media option as ‘print’.
<%= stylesheet_link_tag 'pdf' ,:media=>'print' %>
If pdf containing images which generate on the fly.so instad of using
<%= image_tag %>
use
<img src=" " >
Before rendering PDF validate HTML,like whether all tags are close properly or not.otherwise it gives an parse error.
Now You are ready to Generate PDF. Hurray!!!!!!!!!
How to generate Header, Footer,Page Number and Automation Of HTML Validation will be discussed in next post.
In many web site we have seen that on selecting country,
state or city list is updated.
In this article i am showing how to update children select list on changing parent list.
To do this i am using jquery and ruby on rails.although it will works for almost all languages
For this article, I am updating city list on changing states.
So one state has many cities,and city belongs to state.
<html>
<head>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
$("#states").live("change",function(){
state_id = $("#states").val();
$.ajax({
type: "GET",
url: "/city_list.xxx",
/*or any server side url which generate citylist for rails
"/states/city_list"or<%= city_list_states_path%> */
data: "state_id="+state_id,
/*here we are passing state_id to server based on that on
he can find out all the city related to that states */
success: function(html){
/*html content response of city_list.xxx */
$("#city_list").html(html);
}
});
});
</script>
</head>
<body>
<div id="state_list">
<select id="states">
<option>a</option>
<option>b</option>
</select>
</div>
<div id="city_list">
<select id="cities">
<option value="1">aa</option>
<option value="2">aaa</option>
</select>
</div>
</body>
</html>
and city_list.xxx gives following html
on processing state id which we have pass as state_id
<select id="cities"> <option value="3">bb</option> <option value="4">bbb</option> </select>
In many website we have seen that on checked or unchecked one box
all the check box are checked or unchecked.
Now in this article i am showing how to checked unchecked all the check box
<html>
<head>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
$("#check_all").live("click",function(event)
{
if($("#check_all").hasClass('not_checked'))
{
$("#check_all").removeClass('not_checked');
$(".check-box").attr('checked',true);
}
else
{
$("#check_all").addClass('not_checked');
$(".check-box").attr('checked',false);
}
});
</script>
</head>
<body>
<table>
<tr>
<td>Select/Deselect</td>
<td><input type="checkbox" class="check-box not_checked" id="check_all"></td>
</tr>
<tr>
<td>First</td>
<td><input type="checkbox" class="check-box" id="check_box2"></td>
</tr>
<tr>
<td>Second</td>
<td><input type="checkbox" class="check-box" id="check_box3"></td>
</tr>
<tr>
<td>Third</td>
<td><input type="checkbox" class="check-box" id="check_box4"></td>
</tr>
</table>
</body>
</html>
In this setting checked attribute true/false alternatively by clicking on
select/deselect for alternate removing and adding class
not_checked depending upon that we are setting true and false
Observer classes respond to lifecycle callbacks to implement trigger-like behavior outside the original class. This is a great way to reduce the clutter that normally comes when the model class is burdened with functionality that doesn‘t pertain to the core responsibility of the class.
In my project,I have to track certain action (create and update) of user on particular model basically i am maintaining some kind of log, or audit trails.In my application eventlog model has attribute user and body.
class EventlogObserver < ActiveRecord::Observer
observe :model1, :model2
def after_create(record)
@eventlog = Eventlog.new
@eventlog.body = record.class.to_S+“Created at”+Time.now
@eventlog.save
@event
end
def after_update(record)
@eventlog = Eventlog.new
@eventlog.body = record.class.to_S+“Updated at”+Time.now
@eventlog.save
end
end
This eventlog_observer.rb is stored in app/model
Now Configuration add following line in /config/environment.rb config.active_record.observers = :eventlog_observer
In rails there are various callbacks on which you trigger some common behaviour
and many more you can also refer from http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html
For further reference http://api.rubyonrails.org/classes/ActiveRecord/Observer.html
We can include another html page using jquery load method
example is as shown below
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Loading an Html page</title>
<script src="jquery.js" type="text/javascript"></script>
$(document).ready(function() {
$('#loadpage').load('load.html or any server side page');
});
</head>
<body>
<div id="loadpage" ></div>
</body>
</html>
In normal rails application contain one database,but if we want rails application having more than one database that is multiple data base. we can achieve this using multiple way.one of the way is i am showing here.it’s just 3 steps.
Lets take an e.g Project has many milestone and milestone has many task
In normal scenario model looks like following way
class Project < ActiveRecord::Base has_many :milestones end class Milestone < ActiveRecord::Base has_many :tasks belongs_to :project end class Task < ActiveRecord::Base belongs_to :milestone end
Now we want that milestone is stored on milestone_db database and task on task_db database
Now to achieve this we have to do the following steps
1) Edit Database.yml
milestone_dev: reconnect: false encoding: utf8 username: <user_name> adapter: mysql database: milestone_db pool: 5 password: <password> task_dev: reconnect: false encoding: utf8 username: <user_name> adapter: mysql database: task_db pool: 5 password: <password>
Now create milestone_db and task_db database.
2) Edit milestone.rb and task.rb
class Milestone < ActiveRecord::Base #add this line to use milestone_db self.establish_connection :milestone_dev has_many :tasks belongs_to :project end class Task < ActiveRecord::Base #add this line to use task_db set_table_name "tasks" belongs_to :milestone end
3) After editing model edit migration file
class CreateMilestones < ActiveRecord::Migration def self.connection Milestone.connection end ..... end
Now rails application is ready with multiple database.
Here it is how we can do that magic,
if( isset($_GET['function']) ) {
switch( $_GET['function'] ) {
case ‘dosomething’:
dosomething();
break;
case ‘dosomethingelse’:
dosomethingelse();
break;
}
}
And then link to script.php?function=dosomething
Benifit :
When a search engine visits the dynamic url like product.php?id=test it does not give much importance to that URL as search engine sees “?” sign treat it as a url which keeps on changing. so we’re converting the dynamic URL like the product.php?id=test to static url format like product-test.html. We’ll rewrite the url in such a way that in browser’s address bar it will display as a product-test.html but it actually calls the file product.php?id=test. So that why these kind of URL also named as SEO friendly URL.
How to do using Apache ?
To rewrite the URL you must have the mod_rewrite module must be loaded in apache server. And furthermore, FollowSymLinks options also need to be enabled otherwise you may encounter 500 Internal Sever Error.
The Procedure
For rewriting the URL, you should create a .htaccess file in the root folder of your web directory. And have to put the following codes as your requirement.
Options +FollowSymlinks
RewriteEngine on
RewriteRule ^(.*)\.htm$ $1.php [nc]
The following example will rewrite the test.php to test.html i.e when a URL like http://railstech.com/test.htm is called in address bar it calls the file test.php. As you can see the regular expression in first part of the RewriteRule command and $1 represents the first regular expression of the part of the RewriteRule and [nc] means not case sensitive.
Options +FollowSymlinks
RewriteEngine on
RewriteRule ^product-([0-9]+)\.html$ products.php?id=$1
The following example will rewrite the product.php?id=test to porduct-test.html i.e when a URL like http://railstech/product-test.html calls product.php?id=test automatically.