Dev-Feeds

is_a()

addr = Array.new
addr.is_a?Array #returns true

dd = 11 # which means tha month november
dd_end_txt = `date -d "#{mm}/1 + 1 month - 1day"`
# which returns "Sat Nov 30 00:00:00 IST 2013\n"
dummy = dd_end_txt.split(" ")
dd_end = dummy[2] if(dummy != nil)

# Result is 30

Ruby
chars = ("a".."z").to_a + ("1".."100").to_a
random1 = Array.new(10, '').collect{chars[rand(chars.size)]}.join

Javascript:
var rand = Math.random() * 1000000000 * Math.random();
or
var rand = Math.random() * 1000000000


This is another efficient way to generate random number

Example: 
@user = Users.find(params[:id])
@user_new = User.new(@user.attributes)
@user.created_at = Time.now #update the field in the new record
@user_new.save

Javascript
var str = "055"
str = str.parseInt;
alert(str);    // this alerts the integer value 55

<%= '&nbsp;' * 5 %>

Outputs:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;

numeric_var  =~ /^[-+]?[0-9]*\.?[0-9]+$/

To get the current time:
time = Time.now

To get the current year:
year =  Time.now.Year

Search past 3 months records: 
Event.find(:all, :conditions => ["created_at > ? ",Time.now - 3.month])

This will create an array with the 10 empty elements.

>> Array.new(10, '')
Output
=> ["", "", "", "", "", "", "", "", "", ""]

To run the single migration in the db.

rake db:migrate       # Runs the full db migration
rake db:migrate VERSION=x #Runs the particular version

  dERs = Student.find(:all,:select => "id", :conditions => "")
  dER_ids = dERs.map(&:id)

This updates all records that mathcing with the given conditions

 People.update_all( "name = 'Joe'", "name ilike '%joe%'" )

cookies[:login] = { :value => "asdf", :expires => Time.now + 600} 

The above cookie will :expires in 10 min .

To Delete the Cookie in Ruby on rails:

cookies.delete :login 

To Delete Cookie in Javascript:

createCookie(":login","",-1); 

Create new controller in ruby on rails is the easy thing. Just follow the following process

[root]# script/generate controller <controller-name>

Sample
script/generate controller registration

this will genereate the following folders/files.

      exists  app/controllers/
      exists  app/helpers/
      create  app/views/registration
      exists  test/functional/
      create  app/controllers/registration_controller.rb
      create  test/functional/registration_controller_test.rb
      create  app/helpers/registration_helper.rb

Slicing the string or characters from the given start position with the given length of characters.

Look at the qucik example:

        dob = '10/13/1986'
        dob_mm = dob.slice(0,2)  #this returns 10
        dob_dd = dob.slice(2,2) #this returns 13
        dob_yy = dob.slice(4,4) #this returns 1986

Some of the predefined methods


"Worker".downcase #it returns "worker"
"worker".upcase #it returns "WORKER"
"worker".capitalize # this returns "Worker"


Capitalize function is very similar to the ucfirst() method in php.

Symbolic links in linux is similar to shortcut file in windows.
It is higly recommended for the security reasons in linux environment.

Soft Symbolic Link:

ln -s <original-folder-path> <sympoli-file or folder name>

E.g:
ln -s /usr/local/apache/logs logs

join() method implod the character or string between the single dimension array elements.

E.g:
x = [1,2,3,4]
x.join(",") #This returns "1,2,3,3"

rows.each do |row|
puts  row.id
end

Here rows is an array.