Sampathaya ONLINE

Why am I getting Paperclip::CommandNotFoundError

2012-01-31T21:25:00.000-08:00

If you are dealing with the videos and paperclip, then you probably faced to above error while uploading and converting. this is how to solve the problem.

install imagemagick
sudo apt-get install imagemagick

check the converter
which converter

above command will give the path of converter resides. for example /usr/bin/convert. open the ruby on rails development.rb file and enter the following line.

Paperclip.options[:command_path] = "/usr/bin"

restart the server and you should be able to upload the videos.

is still getting the errors, then open the terminal and see the server logs. if you see following errors on the logs ,

[paperclip] ffmpeg -itsoffset -4 -i "/tmp/stream20120201-2998-djfnsu.mp4" -y -vcodec mjpeg -vframes 1 -an -f rawvideo -s 72x72 "/tmp/stream20120201-2998-djfnsu.jpg20120201-2998-1ecbagd" 2>/dev/null
[paperclip] An error was received while processing: #
[paperclip] ffmpeg -itsoffset -4 -i "/tmp/stream20120201-2998-djfnsu.mp4" -y -vcodec mjpeg -vframes 1 -an -f rawvideo -s 120x120 "/tmp/stream20120201-2998-djfnsu.jpg20120201-2998-r01kob" 2>/dev/null
[paperclip] An error was received while processing: #
[paperclip] ffmpeg -itsoffset -4 -i "/tmp/stream20120201-2998-djfnsu.mp4" -y -vcodec mjpeg -vframes 1 -an -f rawvideo -s 200x200 "/tmp/stream20120201-2998-djfnsu.jpg20120201-2998-1s3s6z9" 2>/dev/null
[paperclip] An error was received while processing: #

then go back to terminal and run the following commnad.

sudo apt-get install ffmpeg

restart the server and check the uploads. if still not lucky again check the logs for error. you might be get following error.

Unknown encoder 'libmp3lame'

then run the following command.

sudo apt-get install ffmpeg libavcodec-extra-53
or
sudp apt-get install ffmpeg libavcodex-extra-52

now you should be fine. if not please contact me.

happy coding.

How to fix phpMyAdmin 404 Not Found error in Ubuntu

2012-01-29T22:19:00.000-08:00

If you are an Ubuntu user and some of you should already got above error. installing and uninstalling phpmyadmin , restarting server , restarting pc not solved the problem?.

then try this out

Enter the following in your terminal:

sudo dpkg-reconfigure -plow phpmyadmin

Reinstall database for phpmyadmin: Select “No”

Web server to reconfigure automatically: Select “apache 2″

It should world now. If not, do the following to include the phpMyadmin-shipped Apache configuration into Apache:

sudo ln -s /etc/phpmyadmin/apache.conf /etc/apache2/conf.d/phpmyadmin.conf

Restart apache:

sudo /etc/init.d/apache2 restart

That’s it. Let me if you have any doubts in the comment.

install ruby on rails on UBUNTU

2012-01-17T21:45:00.000-08:00

step 1. Install dependencies

Install git : Git is the most popular (as well as fast and efficient; Linux kernel uses it; developed by Linux Torwalds, the same guy who developed Linux kernel) open source version control system. You can install it in one simple command to install it from the official package repository -

sudo apt-get install git

[You could also install git from the source (Download the source code, extract it and execute make && sudo make install) ]

Install Curl : Curl is a command line tool to get a file from FTP/HTTP/HTTPS server. To install, open terminal and execute the command -

sudo apt-get install curl

step 2. Install RVM (Ruby Version Manager)

Open terminal and execute the command (I assume you’ve already completed the step 1, otherwise first do that) -

bash < <(curl -s https://rvm.beginrescueend.com/install/rvm)

Now, you might have to edit the bashrc file to load RVM in shell session. To do that type -

gedit ~/.bashrc

and add the following line to the end (and save the file)

[[ -s "$HOME/.rvm/scripts/rvm" ]] && source "$HOME/.rvm/scripts/rvm" # Load RVM into a shell session *as a function*

Then reload the shell session using the command -

source ~/.bashrc

Now you can test whether the RVM has been installed successfully or not. Open terminal and execute the command -

type rvm | head -1

After executing above command you should be getting this output -

rvm is a function

That’s All.. You’ve successfully installed the RVM. Next, you are supposed to install few additional dependencies. To find out those programs type -

rvm requirements

After executing the above command, install the additional packages recommended by RVM -

sudo apt-get install build-essential openssl libreadline6 libreadline6-dev zlib1g zlib1g-dev libssl-dev libyaml-dev libsqlite3-0 libsqlite3-dev sqlite3 libxml2-dev libxslt-dev autoconf libc6-dev ncurses-dev automake libtool bison subversion

step 3. Install Ruby

Now, it’s time to install the ruby version you want (you’re recommended to use either 1.8.7 or 1.9.2). The generic syntax is rvm use version_name. It will also install the associated packages such as RubyGems and Bundler.

rvm install 1.9.2

Then select the version, you want to use -

rvm use 1.9.2

If you aren’t sure about the ruby version currently being used, then type -

ruby -v

step 4. install Database

Now its time to install mysql database.

sudo apt-get install mysql-server mysql-client
sudo apt-get install libmysql-ruby libmysqlclient-dev
sudo gem install mysql

step 5. install Rails

Finally, you can install the rails gem using a simple command -

gem install rails

That’s All.
Now, create a sample application (just for testing) using Ruby on Rails.

rails new my_app
bundle install
cd my_app
rails server

Then open your browser and type the following address (to see the application running) -

http://localhost:3000

if you are successfully followed and were able to run the first application , please feel free to keep small comment here. it will motivate me to upload more articles.

thanks and happy coding

How to extract values from find_by_sql or join query in Ruby on Rails?

2011-10-27T19:09:00.000-07:00

If you are a developer or designer on the ROR , then you might be facing a problem to extract values from rails find_by_sql method.
Usually I'm using this method to run complex sql queries. there can be many reasons. my main reasons to use this method are

1. Avoid multiple hits to Database
2. Less processing
3. Super fast
4. Reduced data set

Lets say you are having multiple models and you needs to join those table to get some results.
Shop , Book , Author , Tag , Customer , Stock
you can use the rail's traditional join or find_by_sql method. both are same and you can choose whatever you need.

method 1 :
Shop.joins(":books => [ { :author => :tag } , :customer ]").where("xxxxxxxxx").select("xxxxx").group("xxxxxxxx")

method 2 :
Shop.find_by_sql("select * from shops s outer join books b on b.shop_id = s.id xxxxxxx ")
Both above queries will return the basic object as a results. for example it will returns the Shop active record object. you wont see the results from the select clause. so here is the way to get that. super simple.

shops.each do |shop|
shop.attributes().each do |attr|
column = attr[0]
value = attr[1]
end
end
Cheers!!! Happy coding.......

Google Wallet

2011-09-26T10:46:00.000-07:00

GOOGLE .... GOOGLE

What are they doing? I fell they are going to be the leader of everything. Actually as I aware Dialog Telecom ( biggest telecommunication company in sri Lanka) start to developed this system while ago and at that time I was an employee. Not sure about the current situation of that project.

by the way, Google introduces this excellent system to world. Now we don't need to carry our money wallet to buy stuffs. even we don't need to carry credit card. So easy ... when you are walking just take your Google enabled phone.

this is how is it work.

Basically this is work with master , city credit cards and google prepaid cards. if you have one of those you can save those details to secured chip inside the phone. when you go to shopping rather than using cash or cheque you can use your phone to pay.

fully secured and super easy. right now it supports only 3 gateways and that will support all the gateways soon. believe me. its Google man. :)

Another benefits are you are eligible to use that as a gift cards and you can get rewards from the merchants.

Stay tune. some more are coming......

Drugs ruins our life

2011-08-23T08:58:00.000-07:00

These photos are collected at the police station, Multnomah, Oregon.
To the left are photos of when they were first at the police station.
Photos from the right side a few years later when they re-addicted to the drugs.

Cute little Kittens

2011-08-23T08:52:00.000-07:00

ONLY WOMEN USE BRA TO COVER THEIR LOVELY ASSETS ???

2011-08-23T08:50:00.000-07:00

Q: Which is the striped BRA?
zeBRA   Q: Poisonous BRA?
coBRA   Q: Mathematical BRA?
algeBRA   Q: Sunsign BRA?
liBRA   Q: Magical BRA?
aaBRA ka daBRA   Q: Religious BRA
BRA hmin!   Q: Metallic bra
BRAss
  Q: Anjelina jolly' Bra
BRAd pit...
  Q: Botany BRA
BRAnch
  Q: Marketing BRA
BRAnd!
  Q: AMERICAN PRESIDENTIAL BRA
BRAaak Obama
  Q: Punctuation k liye bra
BRAcket
  Q: Scary bra....
GhaBRAahat!!!!
  Q: Cricketers ka bra
BRAdd hogg
  Q: How does d donkey cry...
BRAAAAA!! Braaaaa!!
Braaaaaaaaaa!!!
  Q: A room where BRA's are kept..
LiBRAry
  Q: Bra which became the american president and inspired the whole world,
aBRAham Lincoln!
  Q: The BRA which holds the record for most no of T20 runs in an innings?
BRAndon McCullum.
  Q: which bra is very important for any vehicle
BRAke

AND U THOUGHT ONLY WOMEN USE BRA TO COVER THEIR LOVELY ASSETS ???

london olympics

2011-08-23T08:47:00.001-07:00

Save the world and trees

2011-08-23T08:45:00.000-07:00

Install apache on ubuntu

2011-07-28T13:21:00.000-07:00

its very straight forward

open console and write :

sudo apt-get install apache2

ubuntu will ask the password and take care of it.once it done open any browser and write http://localhost

you should get "It Works!!" message. otherwise post the issue here. we will help you.

start / stop / restart the server

sudo /etc/init.d/apache2 start
sudo /etc/init.d/apache2 stop
suco /etc/init.d/apache2 restart

apache2 is autostart with system starts. to avoid that please run this command on terminal.

sudo update-rc.d -f apache2 remove

to restore the settings

sudo update-rc.d apache2 defaults

Changing the default localhost folder
By default, apache will operate on the “/var/www” folder. This means that whatever files you place in this /var/www folder will be visible from the URL http://localhost. In some instances, you may want the “localhost” to point to another folder instead, say /home/user/public_html. Here is how you do it:
First, make sure the /home/damien/public_html folder exists. Create a simple html file, name it index.html and place it in the public_html folder.
Open a terminal and type:
gksu gedit /etc/apache2/sites-enabled/000-default
Change DocumentRoot /var/www to DocumentRoot /home/user/public_html.
Change to .

Save and exit the file.
Restart the apache
sudo /etc/init.d/apache2 restart
Now, in your browser, reload the URL http://localhost. You should see the html file that you have placed in the public_html folder.

Configuring different sites
The above trick allows you to change the default operating folder of apache, however, some of you might not want to override the default settings. An alternative is to create multiple sites and point apache to the active site.
Create a new settings file for your new site.
sudo cp /etc/apache2/sites-available/default /etc/apache2/sites-available/site1
Next, edit this settings file.
gksu gedit /etc/apache2/sites-available/site1
Change DocumentRoot /var/www to DocumentRoot /home/user/public_html.
Change to .
Save and exit the file.
Disable the default setting and make active the site1 settings
sudo a2dissite default && sudo a2ensite site1
Lastly, restart the apache.
sudo /etc/init.d/apache2 restart
With this trick, you can create multiple site configuration file, each pointing to a different folder. You can then easily switch between the sites with the a2dissite and a2ensite command
Enabling .htaccess file
.htaccess file is a powerful file that can be used to control and customize a site server behavior without editing the core Apache module. By default, the .htaccess functionality is turned off and all instances of .htaccess files are completely ignored. The server will not even attempt to read .htaccess files in the filesystem.
To enable .htaccess file, open up the settings file that you have created earlier:
gksu gedit /etc/apache2/sites-available/site1
Scroll down the file until you see the part ““. Underneath that line of code, change AllowOverride None to AllowOverride All.

Laptop caused to dead

2011-06-08T20:30:00.000-07:00

A well known family in Mequon lost their 25 year old son
(Arun Gopal Ratnam) in a fire at home June 4th.

This is what happened.

He graduated with MBA from University of Wisconsin-Madison
two weeks earlier and came home.

Had a lunch with his dad at home and decided to go back to
clean up his room at school.

Father told him to wait and see his mother
be for e he goes back for a few days.

He decided to take a nap while waiting for his mom
to come home from work.

Neighbors called 911 when they saw black smoke
coming out of the house.

Their 25 year old son Arun died
in the three year old house.

It took several days of investigation
to find out the cause of the fire.

It was determined that the fire was caused
by lap top in the bed.

When the lap top is on the bed
cooling fan does not get air to cool the computer
and that is what caused the fire.

Uneven surface of the bedsheets has blocked the
air intake vent below the CPU fan.
When the laptop is placed on a flat surface i.e. on desk/table,
there is a gap between the desk surface and the base of the casing
to allow air to flow/suck in through the air intake vent
by the CPU fan to cool the CPU.
This paragraph is added in by sender for better understanding of the scenario.

He did not even wake up to get out of the bed
he died of carbon monoxide (CO).

The reason I'm writing this to all of you is that
I have seen all of us using our lap top in bed.

Let us all decide and make it a practice not to do that.

Risk is real.

Let us make it a rule not to use lap top in bed or
put computer on bed with blankets and pillows around.

Broadcast this message & you may save others!

Agent admitted failure to sign using the key. Permission denied (publickey).

2011-06-01T21:51:00.001-07:00

Agent admitted failure to sign using the key.
Permission denied (publickey).

I got above error while connecting and cloning my git repository. i have spent almost 6 hours to find the solution. finally i found some solution to overcome this issue.

open the terminal and enter this command

SSH_AUTH_SOCK=0

and then enter your clone command without sudo option.

git clone git@account.beanstalkapp.com:/repo.git

please note that account and repo should be change according to your application.

hope some one will get advantage from this post.

thank you

Agent admitted failure to sign using the key. Permission denied (publickey).

2011-06-01T21:50:00.000-07:00

Delicious acquired by the YOUTUBE

2011-04-27T21:49:00.000-07:00

Delicious has been acquired by the founders of YouTube, Chad Hurley and Steve Chen. As creators of the largest online video platform, Hurley and Chen have firsthand expertise enabling millions of consumers to share their experiences with the world. Delicious will become part of their new Internet company, AVOS.

Delicious (formerly del.icio.us, pronounced "delicious") is a social bookmarking web service for storing, sharing, and discovering web bookmarks. The site was founded by Joshua Schachter in 2003 and acquired by Yahoo! in 2005.

By the end of 2008, the service claimed more than 5.3 million users and 180 million unique bookmarked URLs.It is headquartered in Sunnyvale, California.

Is our generation messed up?

2011-03-17T00:06:00.001-07:00

Little red riding hood didn't listen to her mother

Snow White lived with seven men...

Pinocchio was a liar

Tarzan walked without clothes on...

Sleeping Beauty slept the whole day until a guy kissed her...

Cinderella was dancing with a guy who she just met, till 12 in the night...

These are the stories our parents raised us with, and then they complain our generation is messed up.

100 Years of Earthquakes

2011-03-17T00:03:00.000-07:00

Japan's earthquake shook the entire world. We talked about it here. Photographs of the earth and air.
Summary of the Geological Society of London of the most powerful earthquake in the last 100 years. In order to understand the power of aftershocks - a little help.
What is the magnitude of 1. If it is very rude - imagine that you have jumped to the floor apartments with closet. Your neighbors will feel virtually no vibration. Earthquake at 2 points almost palpable. The increase in magnitude at 1.0 corresponds to an increase in amplitude in 10-fold increase in energy is about 32 times. In Japan it was 9.1.

1. April 18, 1906, San Francisco.

At 5:12 am in San Francisco there was a major earthquake, whose magnitude was 7.8 on the Richter scale. Tremors were felt even in the middle of Nevada, located deep in the continent. As a result of the disaster, almost 80% of the buildings in the city of San Francisco was destroyed, their homes were 300 000, 3000 - died.

2. December 28, 1908, Messina, Italy.

Epicenter of the earthquake with magnitude 7.5 points located in the strait between Sicily and the peninsula. As a result of this earthquake, which is considered the most powerful European earthquake, were almost completely destroyed the city of Messina and Reggio Calabria. In Messina lost almost half of the residents. The total number of victims is estimated at 70 -100 000 people (some sources name the figure to 200 thousand).

3. September 1, 1923, Tokyo-Yokohama, Japan.

This earthquake of magnitude 8.3 points still called the Great Kanto earthquake, as the Japanese Kanto province most affected by the strike element. For two days there was 356 aftershocks, and the height of the tsunami in Sagami Bay has reached 12 meters. The death toll in the disaster is estimated at 142,800 people.

4. Quetta, Pakistan, in 1936.

The earthquake completely destroyed the city's infrastructure, the death toll to nearly 40,000 people, with damage estimated at U.S. $ 25 million.

5. Concepcion, Chile, 1939.

Magnitude quake was 8.3 points. Killed 28 000 people, the damage amounted to nearly $ 100 million.

6. December 26, 1939 Erzincan, Turkey.

The city routinely had to endure the powerful earthquake. In 1939, the element has claimed the lives of 36 to 39 thousand people.

7. February 29, 1960, Agadir, Morocco.

An earthquake measuring 5.9 points only lasted 15 seconds, but the death toll was 15,000 people, injured 12,000, 35,000 were left homeless.

8. Chimbote, Peru, 1970.

An earthquake measuring 7.7 points seriously damaged the fishing industry enterprises, which caused unemployment and impoverishment of the population for several years. At the time of the earthquake killed 67,000 people, with damage estimated at $ 550 million.

9. July 27, 1976, Tien Shan, China.

This earthquake of magnitude 8.2 in the score is considered one of the largest by number of victims in the history of observations. Then the element has claimed more than 650,000 lives.

10. February 4, 1976, Guatemala.

The earthquake of magnitude 7.5 stars died more than 22 thousand people, and 70,000 were injured. Damage estimated at 1.1 billion dollars.

11. September 19, 1985 Mexico City, Mexico.

This earthquake of magnitude 8.1 score is considered one of the most devastating earthquakes of America. The number of dead was then 9,000 people and injured were 30,000 and 100,000 were left homeless.

12. December 7, 1988, Spitak, Armenia.

Magnitude of a catastrophic Spitak earthquake was 7.2 magnitude. The city of Spitak and 58 villages were completely destroyed. The number of dead reached 25 thousand and 514 thousand were left homeless. Damage was estimated at 14 billion dollars.

13. October 17, 1989, San Francisco, California, USA.

Earthquake, magnitude of which was 7.1 magnitude, occurred just before the baseball game "World Series", so in the U.S., this earthquake is also called the "earthquake World Series." In comparison with other earthquake victims was not much: 68 people. Tremors were completely destroyed by a network of roads, and the overall material damage estimated at $ 6 billion.

14. January 17, 1995, earthquake in Kobe - one of the largest in Japan.

Magnitude quake was 7.3 points. Killed 6,434 people, damage totaled $ 200 million.

15. August 17, 1999, Izmit earthquake in Turkey.

Magnitude 7.6 points, the number of victims amounted to 17,217 people, more than 43 thousand were injured. The earthquake triggered a fire at the refinery on fire which took several days. The total damage amounted to $ 25 billion.

16. December 26, 2004, earthquake in the Indian Ocean.

The magnitude was 9.1 points. The earthquake occurred most deadly tsunamis in modern history, killing nearly 300 000 people. The horrific earthquake changed the Earth's rotation rate, because of what knocks have become shorter in 2.68 microseconds.

17. May 12, 2008, Sichuan earthquake, China.

Magnitude was 8 points. Echoes of this earthquake were felt even in Russia. The number of dead reached 68 thousand people, the damage - 20 billion dollars.

18. February 27, 2010, Maule Region, Chile.

Magnitude earthquake in Chile was 8.8 points, the total number of dead had reached almost 800 people. The earthquake occurred tsunami, which reached even to Australia.

19. March 11, 2011, earthquake off the island of Honshu, Japan.

Magnitude up to 9.1 points - this is the most powerful earthquake in Japan on record. March 14, official sources reported nearly 5000 dead, but this figure is not final.

20. The biggest tsunami.
The highest wave of the tsunami, scientists reported in the Gulf fordoobraznom Lita, located in southeast Alaska.

Natural disaster occurred in the evening July 9, 1958, beginning with the earthquake and landslide at fault Ferueter. It was a landslide caused, which has produced record-breaking wave (524m above sea level). The huge stone mass collapsed into the water from the rocks on the northeast coast of the Gulf. From a height of 910 meters 300 million cubic meters of rock, ice and land have broken down.

Powerful waves move across the bay at a speed of 160km / h. The main blow fell on the southwest coast of the bay Hilbert. Wave was of such magnitude that it is easy to completely perehlestnula a sandbank at the mouth of the bay. La Cosa Gauss, separating the bay from the Gulf of Gilbert, was virtually destroyed by violence of the elements. A huge number of trees wave uprooted and carried away into the ocean. As a result of the disaster in the ground cracks appeared, slipped down the coast, and numerous buildings were destroyed.

Bay Lita was a favorite spot for fishing off the local population. During the accident at the epicenter of the events were three ships. Fishermen felt very strong push that dropped them out of bed, and have witnessed how the giant wave lashed out fiercely at the foot of the mountain.

Witnesses at first thought that they face glacier Lita: a huge boulder, which had seemed strong, was moving toward them. On the space that used to grow lush forests, the wave leaving only bare rock at an altitude of 600m. Wave lifted one of the barges and dumped it into the ocean, playfully moving through the shallows. The vessel was separated into pieces, but luckily he survived and the fishermen were found safe two hours after the accident. Another boat also escaped, but the third drowned - body fishermen have not been found.

WebMatrix - free web design tool for windows

2011-02-08T09:14:00.000-08:00

Microsoft WebMatrix is a tool for web developers who know HTML but want to create sites with more functionality like blogs, CMS, and ecommerce without having to learn how to install a blog, CMS, or ecommerce. It works well for a small business owner who has maintained his or her own site but now wants to add features like databases to the site. But it's not a tool for beginners. You need to know HTML and CSS. It includes tag completion and some tag insights, but it's not WYSIWYG and there are a lot of features hidden in the menus.
Target Market(s): Professional Web Developers or Small Business Owners

WebMatrix is a brand new web development tool from Microsoft that includes everything you need for website development. Start from open source web applications, built-in web templates or just start writing code yourself. It’s all-inclusive, simple and best of all free. Developing websites has never been easier.

Create your website
To get started creating websites, just download and install WebMatrix using the Microsoft Web Platform Installer. You’ll be up and running less than 5 minutes! Once WebMatrix is installed, we make it simple to get and install the latest version of your favorite free web applications such as WordPress, Joomla!, DotNetNuke and Orchard.

Customize your website
Once you’re up and running, you will find that WebMatrix provides all the tools features you’ll need in a single unified interface. Say good-bye to switching between multiple applications just to perform common web development tasks. With WebMatrix, you’re always just a click away from easily editing your files, managing your database and modifying your server settings.

Publish your website
When you’re ready, WebMatrix provides a no-hassle way to show the world your website. Just access our hosting gallery from WebMatrix and you’ll find a hosting provider that is guaranteed to run your site smoothly while also allowing you to publish directly from WebMatrix.

WebMatrix - free web design tool for windows

2011-02-08T09:04:00.000-08:00

Target Market(s): Professional Web Developers or Small Business Owners

http://www.microsoft.com/web/webmatrix/

How to Recover that Photo, Picture or File You Deleted Accidentally

2011-02-08T08:55:00.000-08:00

Have you ever accidentally deleted a photo on your camera, computer, USB drive, or anywhere else? What you might not know is that you can usually restore those pictures—even from your camera’s memory stick.

Windows tries to prevent you from making a big mistake by providing the Recycle Bin, where deleted files hang around for a while—but unfortunately it doesn’t work for external USB drives, USB flash drives, memory sticks, or mapped drives. Luckily there’s another way to recover deleted files.

Note: we originally wrote this article a year ago, but we’ve received this question so many times from readers, friends, and families that we’ve polished it up and are republishing it for everybody. So far, everybody has reported success!

Restore that File or Photo using Recuva

The first piece of software that you’ll want to try is called Recuva, and it’s extremely easy to use—just make sure when you are installing it, that you don’t accidentally install that stupid Yahoo! toolbar that nobody wants.

Now that you’ve installed the software, and avoided an awful toolbar installation, launch the Recuva wizard and let’s start through the process of recovering those pictures you shouldn’t have deleted.

The first step on the wizard page will let you tell Recuva to only search for a specific type of file, which can save a lot of time while searching, and make it easier to find what you are looking for.

Next you’ll need to specify where the file was, which will obviously be up to wherever you deleted it from. Since I deleted mine from my camera’s SD card, that’s where I’m looking for it.

The next page will ask you whether you want to do a Deep Scan. My recommendation is to not select this for the first scan, because usually the quick scan can find it. You can always go back and run a deep scan a second time.

And now, you’ll see all of the pictures deleted from your drive, memory stick, SD card, or wherever you searched. Looks like what happened in Vegas didn’t stay in Vegas after all…

If there are a really large number of results, and you know exactly when the file was created or modified, you can switch to the advanced view, where you can sort by the last modified time. This can help speed up the process quite a bit, so you don’t have to look through quite as many files.

At this point, you can right-click on any filename, and choose to Recover it, and then save the files elsewhere on your drive. Awesome!

Download Recuva from piriform.com

Restore that File or Photo using DiskDigger

Update: it looks like since we first wrote about this, DiskDigger became shareware, which gives you a prompt for every file you save. It’s up to you whether you want to try it—best bet, try Recuva first. You could alternatively use the slightly older, but still totally free, portable version of the application from portablefreeware.com. Thanks, Mary!

If you don’t have any luck with Recuva, you can always try out DiskDigger, another excellent piece of software. I’ve tested both of these applications very thoroughly, and found that neither of them will always find the same files, so it’s best to have both of them in your toolkit.

Note that DiskDigger doesn’t require installation, making it a really great tool to throw on your PC repair Flash drive.

Start off by choosing the drive you want to recover from…

Now you can choose whether to do a deep scan, or a really deep scan. Just like with Recuva, you’ll probably want to select the first one first. I’ve also had much better luck with the regular scan, rather than the “dig deeper” one.

If you do choose the “dig deeper” one, you’ll be able to select exactly which types of files you are looking for, though again, you should use the regular scan first.

Once you’ve come up with the results, you can click on the items on the left-hand side, and see a preview on the right.

You can select one or more files, and choose to restore them. It’s pretty simple!

Good luck recovering your deleted files!

Mongo vs Couch Vs Redis

2011-02-08T08:20:00.001-08:00

Advantages:

Mongo

Lightening fast.
Auto sharding on it's way (August)
Replication is very easy.
You can perform rich queries, can create on the fly indexes with a single command.

Couch

Very persistent, no power failure, system crash will do anything to your data.
Everything is HTTP. You can serve a CouchApp from database itself using views.
Replication is easy, and can be uni or bi-directional.
Conflict resolution is a breeze. For distributed systems, this is a must have.
Uses Erlang, you can run CouchDB even on your tiny phone!
Guys at Meebo created Couch-Lounge, a sharding tool.
Everything on disk. Very durable.

Redis

Lightening fast.
Replication possible.
Cool datastructures available within realm of key-value.

Disadvantages:

Mongo

Very unreliable. No single server durability. If something crashes while it's updating 'table-contents' - you loose all you data. Repair takes a lot of time, but usually ends up in 50-90% data loss if you aren't lucky. So only way to be fully secure is to have 2 replicas in different datacentres.
Indexes take up a lot of RAM. They are B-tree indexes and if you have many, you can run out of system resources really fast.

Couch

Couch maintains a different document for every update you make. This is done to save all revisions of a document. Although this is a positive feature, this fills up your hard disk fast. You can run asynchronous compaction to delete all old revisions, but this generally takes hours and is system intensive. But this is a trade-off for redundancy.

Redis

Memory only.
You can have slaves, but it's not distributed yet. Although they intend to add it in future.

hmmmm. feel the meaning of these poems. woooooow.....

2010-11-15T21:03:00.000-08:00

How to punish for ants........

2010-11-15T20:58:00.000-08:00

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19 Rails Tricks Most Rails Coders Don’t Know

2010-11-14T23:45:00.000-08:00

When looking at my own Rails code and that of the community as a whole, I often see places where certain Rails techniques could have been used, but weren't. As much for my own memory as yours, I thought I'd list down some Rails tricks and tips that can make your application or code more efficient:
Benchmark logic in your controller actions - It's really easy. Use the benchmark class method available on all your models like this:

User.benchmark("adding and deleting 1000 users") do
 1000.times do
  User.create(:name => 'something')
  x = User.find_by_name('something')
  x.destroy
 end
end

Of course, your code would be a lot better ;-) The regular SQL logs are not shown when within the benchmark sections. Only the benchmark results are shown.

acts_as_nested_set - Almost everyone is familiar with acts_as_tree, but acts_as_nested_set snuck into Rails quietly. It's much like acts_as_tree, but with the added benefit that you can select all of the children (and their own descendants) of a node with a single query. A list of the instance methods is available.
Easier collections with to_proc - Sick of writing things like post.collect { |p| p.title } or post.select { |p| p.activated? }.collect{ |p| p.title} ? A little Ruby hackery that allows you to convert symbols into proc references makes it easy. You can write post.collect(&:title) or post.select(&:activated?).collect(&:title) instead! Learn a lot more about this.
Convert arrays to sentences in views - If you were collecting a bunch of names to be shown in a view, you might end up with an array like ['Peter', 'Fred', 'Chris'], and joining these with commas and inserting 'and' before the final one is a common pain. Not so, if you use the array method to_sentence as provided in Rails. names.to_sentence would return Peter, Fred, and Chris.
Send files back to the user - Usually, static files can be retrieved by using the direct URL and circumventing your Rails application. In some situations, however, it can be useful to hide the true location of files, particularly if you're sending something of value (e-books, for example). It may be essential to only send files to logged in users too. send_file makes it possible. It sends files in 4096 byte chunks, so even large files can be sent without slowing the system down.
Iterating through page elements with RJS - Changing page elements with RJS is easy, but what if you don't know exactly which elements you want to change, and would instead prefer to address them with CSS queries? You can with RJS's select method. For example: page.select('#items li').each { |item| item.hide } . Powerful stuff!
Check for existence - When doing a Model.find(id), an exception can be returned if the item with an id of 'id' doesn't exist. If you want to avoid this, use Model.exists?(id) first to get a true or false for whether that item exists or not.
Number helpers for common number tasks - All of these number helpers aren't commonly used but provide great shortcuts: number_to_currency(1234567.948) # => $1,234,567.95 or human_size(1234567890) # => 1.1GB or number_with_delimiter(999999999) # => 999,999,999. There are others.
Testing different route configurations easily - with_routing is a test helper that allows you to temporarily override the default 'routes' in routes.rb for test purposes. Demonstration:

with_routing do |set|
  set.draw { set.connect ':controller/:id/:action' }
  assert_equal(
     ['/content/10/show', {}],
     set.generate(:controller => 'content', :id => 10, :action => 'show')
  )
end

You can learn a little more here.
Get lots of info about requests - Checking request.post? and request.xhr? are popular ways to look for POST and AJAX requests, but some of the other request methods are lesser used. For example: request.subdomains can return an array of subdomains that you could use as part of your authentication scheme, request.request_uri returns the full local request URL, request.host returns the full hostname, request.method returns the HTTP method as a lowercase symbol, and request.ssl? returns true if it's an HTTPS / SSL request.
Improving session performance even more than with ActiveRecord - By default, Rails stores sessions on the local file system. Many users change this to using ActiveRecordStore to store sessions in the database. An even faster alternative is to use Memcached to store sessions, but that takes a lot to set up (and isn't available unless you run your own servers, etc). But you can get faster than ActiveRecordStore by using Stefan Kaes' SQLSessionStore. It circumvents the inefficiencies of ActiveRecordStore using his own direct SQL technique to store sessions.
Caching unchanging data at application startup - If you have data that doesn't change between application restarts, cache it in a constant somewhere. For example, you might have a YAML or XML file in /config that stores application configuration data, and you could load it into a constant in environment.rb, making lookups quick and easy application-wide.
Check your views are rendering valid HTML / XHTML - It's not for everyone, but if your output validates as correct HTML / XHTML, it's a sign your views are going to render properly. Scott Raymond has developed a assert_valid_markup test helper that you can use from your functional tests.
Cleaner HTML output testing - Combine why's Hpricot HTML parser and a special test extension, and you can have powerful tests like so: assert_equal "My title", tag('title') or assert element('body').should_contain('something'). This might be ideal for developing tests to test user built templates. In any case, it's nicer than assert_tag!
Run long-running tasks separately in the background - BackgrounDRb is a small framework, by Ezra Zygmuntowicz, that runs as a daemon in the background that can accept tasks your Rails application sends to it, and whose execution is totally separate to your Rails app. It's extremely powerful, and useful for many tasks such as sending hundreds of e-mails, fetching URLs, and other things you don't want to slow down the request times for your main app. One great demo is to develop a task that increments a variable by 1 and sleeps for 1 second. You can then make a Rails method that queries the variable, and see the distinct separation. Learn more.
Make ids in URLs more user friendly - Override the to_param method on your model and return something like "#{id}-#{title.gsub(/[^a-z0-9]+/i, '-')}" to get URLs like so: http://yoursite.com/posts/show/123-post-title-goes-here .. Much nicer for users, and you don't need to change anything with Post.find(params[:id]) as the non numeric characters will be stripped automagically! Get a full explanation here.
Separate out slices of functionality into Engines - Everyone's heard of Rails' plugins, but pitifully few are using Rails Engines! Rails Engines are like plugins on steroids. They can contain their own models, controllers, and views, and integrate with any applications you run them under. This allows you to split out common fragments of functionality (login, user management, content management, etc.) into separate 'engines' to use in your different projects within minutes. No more writing dull login code! Rails Engines is a big deal, but it should be a far bigger deal.
Calculations - Do you want to get maximums, minimums, averages, or sums for data in your tables? ActiveRecord's Calculations make these all possible. Person.average('age'), Person.maximum(:age, :group => 'last_name'), and Order.sum('total') all become a reality. Most can be customized pretty deeply with extra options, so go read about them if they're not already part of your code.
XML or YAML output of your data - It's not necessarily to create a Builder .rxml template for all XML output. ActiveRecord has a to_xml method that will output the object or result set in XML format. It works with simple objects, to complete tables (like User.find(:all).to_xml). Using includes works too, as with Post.find(:all, :include => [:comments]).to_xml. YAML is also supported, by using to_yaml instead.

Using SSL in Rails Applications

2010-11-14T23:41:00.000-08:00

If your web application manages any private information, you should be using SSL (https://) for those parts of the application. Any data sent over a plain http connection can be “sniffed” by any ISP along the route that the packets take if you aren’t using SSL.
Fortunately, implementing SSL isn’t too hard, once you know what you need to do. This article will talk you through the process. These are the steps we’ll go through:

Create your private key
Create your certificate signing request
Get your certificate
Configure your web server
Set up your Rails application

Creating your private key

The first thing you need is a private key, with which your certificate will be encrypted, and which will be used to encrypt your SSL pages before they are sent. You make the private key yourself. Assuming your server has openSSL installed, enter the following command in an SSH shell:

openssl genrsa -out domainname.key 1024

This creates your private key in the file domainname.key (you should substitute your domain name for domainname, of course, although the name doesn’t really matter). This key is unprotected, so you should ensure that this file is readable only by the root user:

chmod 600 domainname.key

Alternatively, you can create your key in an encrypted form that will require you to specify a passphrase when creating the key, and to enter that passphrase to access the key:

openssl genrsa -des3 -out domainname.key 1024

This makes your key more secure, but it has a big downside: once you’ve installed the key, you’ll need to enter the passphrase any time the web server is rebooted. If you’re not around and there’s an emergency reboot of your server, your site will be down until someone can log in and enter the key.
If you do encrypt your key, don’t forget your passphrase! Without it, your key, and the certificate that uses it, will be worthless, and there’s no way to recover it.

Creating your certificate signing request

Now that you have your private key, you can create the certificate signing request (CSR), which you’ll need to get your certificate.
In the SSH shell on your server, create your CSR as follows:

openssl req -new -key domainname.key -out domainname.csr

You’ll be prompted to provide the name of the company, the country, city, and state, and some other information. The most critical piece of information here is the common name, which must exactly match the domain of the server on which the certificate will be used, including any subdomain. Note that www counts as a subdomain, so one certificate works either with www.domainname.com or with domainname.com. You can also buy a “wildcard” certificate, which works with any subdomain, but they’re much more expensive (at this writing, $199 vs. $19.99 at GoDaddy). (To make your site work with or without the www prefix, you should be redirecting accesses to one or the other, so you’ll only need a certificate for one of them.)
Don’t enter any of the “extra” information that you’ll be prompted for. In particular, don’t enter a challenge phrase, or the certificate signing authority won’t be able to read your request.
The file domainname.csr will now contain a string of text, which you’ll shortly be providing to your certificate authority. The file contents should look something like this:

Getting your certificate

Now you need to choose where to get your certificate, and what level of verification to pay for. To understand the choices, keep in mind that an SSL certificate provides two separate functions:

It certifies, to varying degrees, the identity of the person or business that controls the web site.
It provides the public and private keys for encrypting communications with the site.

You can get certificates at prices ranging from less than $20 to more than $1500, and they all provide the same encryption. The only difference is the degree to which they verify that you are who you say you are, and the seal that they give you to display on your web site. For more on certificates and certificate authorities, see Implementing SSL. Or, if you don’t care about all the fancy stuff (which, for the most part, provides little value) just go to GoDaddy and get your $19.99 Turbo SSL certificate.
The workflow will vary depending on your certificate authority; I’ll describe how it works at GoDaddy.
When you purchase your certificate, you get a credit that is good for one certificate. You then log into the SSL Certificate part of the site and use the credit to request a certificate. The web form provides a form field into which you paste the text from the CSR you generated in the previous step.
When you submit the CSR, the certificate authority will email the administrative contact for the domain to ask if they want to approve the request. This is how they verify that the certificate belongs to the domain. If you purchase a more expensive certificate, at this point they’ll perform additional verification steps to ensure that the certificate belongs to who it says it belongs it.
Once the CSR is approved, you’ll get an email with a link to download a zip file that contains the two certificate files you need to install on your server. One is your certificate, and will be named something like “domainname.com.crt.” The other is the intermediate bundle certificate that establishes the chain that connects your certificate to the signing authority. In GoDaddy’s case, this is gd_intermediate_bundle.crt.
Now is a good time to make a backup of these files. The intermediate bundle is a standard file that you can usually get again, and you can request that your certificate authority re-issue your certificate file. But if you lose the key file, your certificate is worthless, and you’ll have to purchase another one.

Configuring your web server

Now you need to configure your web server for SSL. Just how this is done depends on what server your using, its version, and how it was installed and configured. I’ll describe how it works for a typical Apache 2.x configuration; you may need to adjust this for your situation.
You should already have virtual host definition, either in your httpd.conf file or in an application-specific configuration file that is included into the main httpd.conf by reference. There are two kinds virtual host definitions: name-based, and IP address based. You can’t use name-based virtual hosts with SSL, so you’ll need to have a dedicated IP address for the site that is using SSL. If you only have one IP address for your server, you’ll only be able to have one application. If you want to host multiple applications, your host should be able to provide you with multiple IP addresses.
You’ll need two virtual host blocks, one for the non-SSL parts of the site, and another for the SSL parts. The basic configuration should look something like this:



  Include conf/apps/domainname.conf.common




  Include conf/apps/domainname.conf.common

  # SSL Engine Switch
  SSLEngine on

  # SSL Cipher Suite:
  SSLCipherSuite ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP:+eNULL

  # Server Certificate
  SSLCertificateFile /etc/httpd/conf/ssl.crt/domainname.com.crt

  # Server Private Key
  SSLCertificateKeyFile /etc/httpd/conf/ssl.key/domainname.key

  # Server Intermediate Bundle
  SSLCertificateChainFile /etc/httpd/conf/ssl.crt/gd_intermediate_bundle.crt

  # Set header to indentify https requests for Mongrel
  RequestHeader set X-Forwarded-Proto "https"

  BrowserMatch ".*MSIE.*" \
    nokeepalive ssl-unclean-shutdown \
    downgrade-1.0 force-response-1.0
  
  CustomLog logs/domainname.com-ssl_log \
    "%t %h %{SSL_PROTOCOL}x %{SSL_CIPHER}x \"%r\" %b"

Let’s walk through this. The first virtual host block is essentially the same as what you’d have without SSL, except that you have to specify an IP address (123.456.789.123 in this example). I’ve put all the configuration that would normally go here, to set up the proxy to Mongrel and any mod_rewrite rules, into an include file, domainname.conf.common, which is not shown here. Doing so allows the same commands to be reused in the SSL block.
The second virtual host block defines the same IP address, but this time for port 443, which is the standard SSL port. First we include all the common configuration code to handle mongrel and so forth. Then, finally, comes the SSL configuration directives. We need to turn on the SSL engine, specify the encryption to be used, and point to the three files we generated earlier: the key, the certificate, and the intermediate bundle. (The CSR isn’t needed once the certificate has been generated.) In this example, I’ve shown them going in subdirectories of conf, but you can put them anywhere, as long as these pointers match the location.
Next, we set the request header to tell mongrel when there is an https connection. Don’t leave this out, or you’ll have no end of confusing problems in your Rails code!
Finally, there’s a bit of config to keep Internet Explorer happy, and a custom log definition to log SSL accesses to a separate log file (this last bit is entirely optional).
To test all this, enter

apachectl configtest

in an SSH shell. This will check your config files for syntax errors without actually rebooting the server, so in case there’s a problem you don’t leave the server disabled while you sort out any errors.
At last, you can now reboot Apache (sudo service httpd restart), and if everything is correct, you’ll have an operating SSL server.

Tell your Rails app where to use SSL

With the above setup done, you should be able to browse to any page in your application using either http:// or https://. You’ll probably want to leave parts of the site unsecured, since SSL pages put extra load on the server, so you need a way to indicate which pages require SSL, and which don’t.
The ssl_requirement plugin, written by DHH himself, makes this simple. Install the plugin:

script/plugin install ssl_requirement

And then include it at the top of your application.rb file, which effectively includes it in every controller:

include SslRequirement

Now all you need to do is specify, at the top of each controller, which controller actions require SSL:

ssl_required  :login, :account, :payment, :cart

Be sure to include in this list any create or update actions that process form data from SSL pages. The magic of this is that you don’t need to change any links; any access to an action that requires SSL will automatically redirect to https://. If anyone tries to access a page that is supposed to be secure with an http:// link, they’ll be redirected.
You can also provide an ssl_allowed declaration if there are actions that you want to be able to access either way. Such actions won’t redirect to https:// but if that protocol is explicitly specified in a link, it will work.

Check your Ajax actions

For the most part, that’s all there is to it on the Rails side. There’s just one more thing that may require your attention: actions that service Ajax requests.
On any page accessed with SSL, all Ajax requests must use SSL, or they will fail. To make this happen, all you need to do is include the names of the actions that service the requests in your ssl_required statement.
In some cases, you may have Ajax actions that have no code in the controller, but are just rendering RJS templates or other views. For these actions, you’ll need to add an empty action definition block in the controller, and add the action name to the ssl_required statement.
One obscure case is the text_field_with_auto_complete helper. If you’re using this in your view, you’re probably also using the auto_complete_for :model :field shortcut in your controller. This automatically produces an action to respond to the autocomplete requests. But since the action isn’t explicitly defined, how do you tell it to require SSL? You just need to know what the automatically created action is named, which is auto_complete_for_model_field. Just substitute the names of your model and field, and add this action name to your ssl_required statement.

Check for mixed content

One last thing to watch out for is mixed content. If you’re testing in Firefox, you won’t notice it, but in IE, users will get a security warning if an SSL page accesses any non-secure content. You don’t have to worry about links to images and so forth, as long as they’ve been written as paths without the full domain name; those will automatically use the protocol of the main page. But if you have any full links, you’ll need to make sure they are written as “https://” on any SSL page.
One case where this problem can sneak in is with JavaScript snippets for services such as Google analytics. If you have a Google analytics link on your page, change it from “http://www.google-analytics.com/urchin.js” to “https://ssl.google-analytics.com/urchin.js”. (Google has now change its analytics code so this isn’t necessary if you’re using their current code.) This will work fine on all pages, whether they use SSL or not, and it will keep the analytics link from triggering the mixed content warning.

Now you have SSL, but …

Now your site can send pages in encrypted form, so they can’t be snooped on by prying eyes along the path between your server and your user’s computer. And the user can examine the certificate to see to whom it was granted, and know that the browser would warn them if the domain name didn’t match.
Of course, there’s much more to keeping your users’ data secure. You need to ensure that all model requests are properly scoped, and for internal security, you need to make sure that confidential information isn’t leaking out in your logs, exception reports, and backups.