The Hitchhiker’s Guide to Ruby On Rails Galaxy

Records of my voyage through RoR Galaxy

Posts Tagged ‘rails’

How to parse a tweet text from Twitter using Ruby to parse-out ‘@’ and ‘#’

Posted by arjunghosh on March 5, 2009

Well lot of us love @twitter and also Ruby, and some time work on both 🙂

And often we need to do the folowing with a tweet

Well I had to do the following quite often:-

Take out the ‘@’ (i.e. @replies )and ‘#’ (i.e. hashtags ) from a tweet and separate it from the text part.

For example, we have a tweet:

@myfriend1 @myfriend2 this is a sample text #link #text

Now I want this tweet to be seperated into the following Array:

[‘myfriend1′,’myfriend2’]

[‘link’,’text’]

and the text only – [“this is a sample text “]

So first had to build a RegE, and then using the ever useful .gsub method of Ruby, created the following:

parsed_text = tweet.text.gsub(/ ?(@\w+)| ?(#\w+)/) { |a| ((a.include?(‘#’)) ? tags : replies) << a.strip.gsub(/#|@/,”); ” }

So the parsed_text has the final text only.  tags is an Array which will contain the hashtags and replies is an Array which will contain the @replies.

The RegEx / ?(@\w+)| ?(#\w+)/ extracts and seperates the hashtags & the @replies and place them in two seperate arrays.

The RegEx /#|@/,” only reples the ‘@’ and ‘#’ symbols in the extracted array elements.

And you can download it from Gist here http://gist.github.com/78498

Also while working on creating the above regular expressions, I found this interesting RegEx testing site called www.rubular.com which will help you write regular expressions very easily.

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A very hip & cool parenting site called lil’grams which is built on RubyOnRails!

Posted by arjunghosh on March 3, 2009

Just wanted to do a very quick post on this very new hip & cool site on parenting – lil’grams

app1

And do you know what, its has been made in RubyOnRails!

Do check out this site. It the brain child of Greg Narain who is a well know serial entrepreneur & social media expert.

Already people are talking about it and when its yet to be launched!!

Actually people like NYTime, CNET, Mashable have been talking about lil’grams for sometime. Even KillerStartups has a mention.

There is also a buzz on twitter too 🙂

Yes, some would say its been in making for quite sometime. But as they say patience has its virtue. Ultimately its a labour of love.

It been really a long journey for me personally too. Have been working on it for quite some time. I still  remember those days of sleepless night, long meeting, etc. 

Though I am yet to be a dad 🙂 (a.k.a am un-married), I too  feel like a proud parent my self on the birth of lil’grams  which I feel is literally my baby! 

If you like (and also dont 🙂 ) do tell us about it here which I assure will be promptly replied to 🙂

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Two of the best help & guide sites for RubyOnRails and Ruby

Posted by arjunghosh on February 27, 2009

Well this is essentially a note to self and well to others too.
The best help documents online for Ruby On Rails and Ruby are these AJAXified websites which allows real-time searching of sytanx and commands.

For Ruby On Rails, it is:

www.railsbrain.com

And for Ruby, we have:

www.rubybrain.com

And the best part is you can even download them so that you can use it offline!

Another good resource for Rails documentaion and help guides is the newly created collaborative effort Rails Guide project. This was started by @lifo as a project to give the rails community a good documentaion which was painfully lacking till now. Since its a collaborative effort, you can participate here. There is even buzz about this project on @twitter

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Using ERB as a dynamic template to create a file whose contents are dynamic

Posted by arjunghosh on February 17, 2009

The following code will create a temporary file for say attaching a vcard file to email.The following code is dynamic to use ERB as a template to create the file dynamically every time with the variable “telephone”,”location”,”email” which gets binded to the ERB file and is under scope.
The code is:-

{
telephone = “347-27456”
location = “New Delhi”
email = “xyz@gmail.com”
vcard = ERB.new( File.open(‘address.vcard.erb’ ){ |f| f.read } ).result( binding )
f = File.new(“temp_file.vcf”,”wb”)
f.puts vcard
f.close
}

and in pastie is here

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Model name in RubyOnRails should ALWAYS be singular!!!

Posted by arjunghosh on December 23, 2008

Model names in RubyOnRails should be Singular. This will create Table name as corresponding Plural names.

You have got to remember that about model naming conventions in rails. . 

I know this is a very basic concept in RubyOnRails but sometimes these simple basic concepts are the ones which slip through the cracks.

Example:

> ruby script/generate model Post

This will create a Model by the name “Post” i.e. singular in english language and a migration to create a table by the name “Posts” which is plural form of “Post”.

I have even put this into a pastie for easier remembarance http://pastie.org/345491

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I am Back!!! and so many interesting changes to Rails…

Posted by arjunghosh on December 23, 2008

Yeah I know its been long since I have been away. Well lot has happened between my last journey  through RubyOnRail’s universe from May 28,2008 to the current date. New Rails 2.0 screencast by Fabio Akita  which is unspired by the Creating a Weblog in 15 minutes the original screencast by David Hansson , Newer version of RubyOnRails (v 2.2.2) are out, Rails officially moved to GitHub and supports  Git as the VCS of choice, Rails thread safety is in (though how is that actually useful ?),  lot of nifty changes in Rails v2.2.  So all in all lot of things have been happening.

I will try to be more regular here. In mean time, everyone who twitter and in New Delhi, India can check out the twitter.com/rubyonraildelhi where I have been posting regular rubyonrail updates and local information. You can find me on twitter here at @arjunghosh.

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How to force the browser to not cache in Rails

Posted by arjunghosh on April 29, 2008

This is a quick note to self. Though,I found this excellent post by Chad while looking for something else but this post had a excellent note on browser cache also. So this post is mostly a re-post from Chad’s.

So here it goes:

To ensure that the page isn’t cached by the browser and will always be re-fetched, add a before_filter to the purchases controller which calls a private method on ApplicationController:

before_filter :no_cache, :only => [:new]
private
def no_cache
response.headers["Last-Modified"] = Time.now.httpdate
response.headers["Expires"] = 0

# HTTP 1.0
response.headers["Pragma"] = "no-cache"

# HTTP 1.1 'pre-check=0, post-check=0' (IE specific)
response.headers["Cache-Control"] = 'no-store, no-cache, must-revalidate, max-age=0, pre-check=0, post-check=0'
end

Now there is a catch – ‘not caching’ only works in Firefox.

Now the above code should have worked for all browser, but it did not work in Safari or in IE 6 and 7. The reason is that any page with an iframe on it will never be cached, and will always be re-fetched.

The solution is iframe. So, we add this to views/foo/new.

<iframe style="height:0px;width:0px;visibility:hidden" src="about:blank"> this frame prevents back forward cache </iframe>

This frame prevents back forward cache. And this works. Now we have cross-browser no-caching in a RESTful. Though this is a hack as Chad says. But it works for me. 🙂

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How to Install Ruby, Rails 2.x, MySQL, SVN, then setup Rails 2.x Application, Configure the database, Run the Rake Tasks, Install plugins and, finally run RSpec for Models on your Local Windows System

Posted by arjunghosh on April 25, 2008

A.) How to setup a Rails 2.x Application on your local system:–
[NOTE: The following steps are for Windows OS environment]

  1. Setup Ruby and Rails on the local system:-
    • Install Ruby on Windows:
      The easiest way is using the One-Click-Installer
      Once the installation is complete, check that path to ruby\bin directory is in your PATH variable (Run “cmd”, then type “path” at the prompt and check that the path is there.
      The great thing about the one-click installer is that it comes with Ruby Gems, Scite pre-installed. The thing to watch out for is that one-click installer does not have the very latest version of Ruby, so when you are reading Ruby Docs, make sure you know which version of Ruby you have (run “ruby -v” in the command prompt)
    • Installing MySQL on Windows:
      First, download and run the latest MySQL. After the files are unzipped, an Instance Config should run automatically (you can run it manually at any time from your MySQL bin directory just run “MySQLInstanceConfig.exe”). Then go through the step as directed.
    • Install Rails on Windows:
      Run the following command: gem install rails –-include-dependencies
      (If this command gives you an error, you do not have the latest version of gems installed. Run “gem -v” to check for the version of RubyGems. It should be 0.9.4. Otherwise, you may probably need to update RubyGems as well.: gem update –system [NOTE: It is recommended that RubyGems version 0.9.4 is used as Rails 2.x had some issue with version 0.9.5. Though this issue had been subsequently resolved]
    • Installing SVN on Windows:
      We use the TortoiseSVN SVN client on our local machine to use SVN.
      We have SVN version on our local system: 1.4.3
      The SVN version installed on the Server, which we were using, can be found by running the command on the server: svn –version
  2. Create a rails 2.x application:-
    SQLite3 is the new default database. So when a rails 2.x application is created, by default the database support, which comes preconfigured, is for SQLite3. So to create a rails 2.x application with MySql support preconfigured, you simply need to run the following command: rails -d mysql testapp
    This will create the skeleton structure for the rails 2.x application with mysql database adapter.
  3. Configuring the database for the application:-
    Now a database.yml file is created in the /config under your application root folder. You need to set the development, production and test database names there. Also you need to put in the database password,if there exist any,So for your database in this .yml file. This password is same as the one you put in while installing mysql on your machine.

    • So for a rails application, database.yml file configuration is as follows:
      development:
      database: testapp_development
      adapter: mysql
      encoding: utf8
      username: root
      password: mypassword
      [Note: password is set here if any]
      socket: /tmp/mysql.sock [NOTE: Similarly for production and test database]
  4. To create the database on the local machine:-
    Run the following command: rake db:create:all
    The above command will create all the three database i.e. development, production and test database as set in the database.yml file
    If you want to start from scratch, you can do rake db:drop:all And in the middle of development we can do rake db:rollback to undo the latest migration file.
  5. To seed the database with initial database:-
    Run the following command: rake db:populate
    This will populated the database with initial data as written in populate rake file. Also a rake task called rebuild has been created so that it becomes easy to do the above steps from dropping a db, re-creating the db,running all the migration and then finally populating it with the initial seed data.
    Run the following command:rake db:rebuild. [NOTE:This rebuild rake task will easily do all the above db related steps. See my previous post for “How to create a rake db:rebuild task”
  6. To run your Rails 2.x application on the local system:-
    Need to first go to root folder of your rails application. For example: F:/Projects/testapp/trunk
    Then run the following command: ruby script/server
    This will run the application in development mode. To run in production mode: ruby script/server -e production
  7. To install rspec plugin for rails application:-
    Run the following commands at the command line:
    ruby script/plugin install http://rspec.rubyforge.org/svn/tags/REL_1_1_3/rspec
    ruby script/plugin install

    and http://rspec.rubyforge.org/svn/tags/REL_1_1_3/rspec_on_rails
    Once the plugin is installed, you must bootstrap your palnglue rails app with RSpec. Stand in the root of your Rails app and run: ruby script/generate rspec
    This will generate the various files needed to use RSpec with Rails.
  8. To run the rspec with rake on the local machine:-
    Run the following command at the root folder of the application: rake spec
    or run specs with scripts/spec command: ruby script/spec spec

B.) How to install a Plugin for Application:–

Stand in the root of your rails app and run:

ruby script/plugin install <here the url path of the plugin to be installed>

C.) Running the RSpec test cases for Models:–

Run using the command:

rake spec:models

D.) Running the RCov:–

Coverage tests can be run using the command:

rake spec:rcov

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How to use “position:relative” in CSS

Posted by arjunghosh on April 23, 2008

First the definition of CSS position Property:

“The position property places an element in a static, relative, absolute or fixed position.”

“We can also say that the CSS positioning properties allow you to specify the left, right, top, and bottom position of an element. It also allows you to set the shape of an element, place an element behind another, and to specify what should happen when an element’s content is too big to fit in a specified area.”

CSS properties can also be dynamically changed with a JavaScript. The syntax is as follows:

object.style.position="absolute"

Example:

h1
{
position:absolute;
left:100px;
top:150px;
}

Possible Values for the “position” property:

static:
This is Default. An element with position: static always has the position the normal flow of the page gives it (a static element ignores any top, bottom, left, or right declarations).
Normally you wouldn’t specify this unless you needed to override a positioning that had been previously set.

#div-1 {
position:static;
}

relative:
An element with position: relative moves an element relative to its normal position, so “left:20″ adds 20 pixels to the element’s LEFT position.
Let’s move div-1 down 20 pixels, and to the left 40 pixels:

#div-1 {
position:relative;
top:20px;
left:-40px;
}

absolute:
An element with position: absolute is positioned at the specified coordinates relative to its containing block. The element’s position is specified with the “left”, “top”, “right”, and “bottom” properties.
Let’s move div-1a to the top right of the page:

#div-1a {
position:absolute;
top:0;
right:0;
width:200px;
}

fixed:
An element with position: fixed is positioned at the specified coordinates relative to the browser window. The element’s position is specified with the “left”, “top”, “right”, and “bottom” properties. The element remains at that position regardless of scrolling. Works in IE7 (strict mode)

An excellent online resource to further understand it is here

Another thing related to CSS positioning is : float
We can “float” an element to push it as far as possible to the right or to the left, and allow text to wrap around it. This is typically used for images, but we can use it for more complex layout tasks.

#div-1a {
float:left;
width:200px;
}

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Rails core has moved to GitHub

Posted by arjunghosh on April 18, 2008

Ya, Ruby on Rails core is now hosted at GitHub, which is uses Git for easy, fast, efficient, distributed version control system and also which looks pretty!!!

In DHH own words,

GitHub has now officially launched and Rails is right there at the premiere. The Rails repository now lives at rails/rails

And you can check it out with:

git clone git://github.com/rails/rails.git

But you will first need Git installed on your machine. For those on Windows machine, you can get that here: msysgit

Also people should have a look at this excellent post by Tim Pope on how to best use Git with Rails. You can have a look at the full tutorial also.

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