HowTo: Import your posts from Blogspot/Blogger

I needed to import blogspot blogs into a different system. I created a plugin that simply parses the xml file that is generated when you export your blogspot blog. Here is the link to github.

HowTo: Check if email really exists

I had a project that wants to check if an email really exists. Here’s what we came up initially. We ended up not using this in production though, but it’s a great tool.

HowTo: Authorize.Net CIM and ActiveMerchant

I’ve started working on a Sample Rails App that uses ActiveMerchant to connect to the Authorize.Net API. Here’s the link.

HowTo: Integrate with ConstantContact

I’ve started working on a plugin for ConstantContact. You can find the latest development here.

I hope you find it useful in integrating your Rails Apps with ConstantContact.

Rescue :me

These rescuers are quite handy to prevent nasty errors in production.

# in application_controller.rb
rescue_from ActionController::RoutingError, :with => :route_not_found
rescue_from ActiveRecord::RecordNotFound, :with => :record_not_found
rescue_from ActionController::MethodNotAllowed, :with => :invalid_method
rescue_from NoMethodError, :with => :show_error
rescue_from ActionView::TemplateError, :with => :template_not_found

private

def route_not_found
render :text => ‘Sorry, we could not find what you were looking for.’, :status => :not_found
end

etc.

HowTo: Changing the column name in a model for validation

Sample code taken from here.

class User > ActiveRecord::Base

HUMANIZED_ATTRIBUTES = {
:email => “E-mail address”
}

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

end

String#present?

>> “brain”.present?
=> true

>> “”.present?
=> false

use something.present?
instead of !something.blank?

HowTo: Add Ajax Indicators

Copy the following code to public/javascripts/application.js

Ajax.Responders.register({
  onCreate: function() {
    if (Ajax.activeRequestCount > 0)
      Element.show('indicator');
  },

  onComplete: function() {
    if (Ajax.activeRequestCount == 0)
      Element.hide('indicator');
  }
});

Add a div element to your view with an id of ‘indicator’. Remember to keep this div from displaying by setting the display attribute to none.

#indicator{style => 'display:none'}
  = image_tag ('/images/my_loading_indicator.gif')


Here is a good site to create your own indicator image.

HowTo: Use older gems

Now that Rails 2.1.1 is out, when you install using the gem, you get Rails 2.1.1. If you want to install an older version, like Rails 2.1.0, you need to specify the version:

sudo gem install rails –version 2.1.0

You’ll do this if you have some dependency on the older rails version. To make sure your app will run when you transfer to a different machine, freeze rails into the vendor directory:

rake rails:freeze:edge TAG=rel_2-1-0

Make sure that your environment.rb specifies the corresponding version.
Finally, you may want to create a new project using an older version of rails. You can do so by:

rails _2.1.0_ project_name

And apparently, you can use that trick for other gem-installed commands, like capistrano.

HowTo: Date operations

I’m just going to copy and paste the code from this site.

Basically, time and date manipulations are easy as long as the operations involved are additions and subtractions. Quoted from the link above:

Not every arithmetic operation makes sense for dates: you could “multiply two dates” by multiplying the underlying numbers, but that would have no meaning in terms of real time, so Ruby doesn’t define those operators.

Remember:

• Time has a unit of 1 secondrequire ‘date’
  y2k = Time.gm(2000, 1, 1) # => Sat Jan 01 00:00:00 UTC 2000
  y2k + 1 # => Sat Jan 01 00:00:01 UTC 2000
  y2k – 1 # => Fri Dec 31 23:59:59 UTC 1999
  y2k + (60 * 60 * 24 * 365) # => Sun Dec 31 00:00:00 UTC 2000

  y2k_dt = DateTime.new(2000, 1, 1)
  (y2k_dt + 1).to_s # => “2000-01-02T00:00:00Z”
  (y2k_dt – 1).to_s # => “1999-12-31T00:00:00Z”
  (y2k_dt + 0.5).to_s # => “2000-01-01T12:00:00Z”
  (y2k_dt + 365).to_s # => “2000-12-31T00:00:00Z”

• While DateTime and Date have a unit of 1 dayday_one = Time.gm(1999, 12, 31)
  day_two = Time.gm(2000, 1, 1)
  day_two – day_one # => 86400.0
  day_one – day_two # => -86400.0

  day_one = DateTime.new(1999, 12, 31)
  day_two = DateTime.new(2000, 1, 1)
  day_two – day_one # => Rational(1, 1)
  day_one – day_two # => Rational(-1, 1)

Printing dates on our views is done by using the method strftime.

d = Date.today # 2008-08-12
d.strftime(‘%b %d, %Y’) # will print August 12, 2008

The following are the format codes. For reference, refer to this site.

Format	Meaning
%a	The abbreviated weekday name (“Sun’’)
%A	The full weekday name (“Sunday’’)
%b	The abbreviated month name (“Jan’’)
%B	The full month name (“January’’)
%c	The preferred local date and time representation
%d	Day of the month (01..31)
%H	Hour of the day, 24-hour clock (00..23)
%I	Hour of the day, 12-hour clock (01..12)
%j	Day of the year (001..366)
%m	Month of the year (01..12)
%M	Minute of the hour (00..59)
%p	Meridian indicator (“AM’’ or “PM’’)
%S	Second of the minute (00..60)
%U	Week number of the current year, starting with the first Sunday as the first day of the first week (00..53)
%W	Week number of the current year, starting with the first Monday as the first day of the first week (00..53)
%w	Day of the week (Sunday is 0, 0..6)
%x	Preferred representation for the date alone, no time
%X	Preferred representation for the time alone, no date
%y	Year without a century (00..99)
%Y	Year with century
%Z	Time zone name
%%	Literal “%’’ character