What is the best way to get the current request URL in Rails?

How can a value be stored so that it's shared across an entire request (i.e. make it accessible in controllers, views and models)?

Which commands adds the data model info to the model file?

Which HTML template languages are supported by Ruby?

In a has_many association, what is the difference between build and new? // user.rb has_many :posts // post.rb belongs_to :user

What is the output of the following code? test*5

Which is the best way to add a page-specific JavaScript code in a Rails 3 app? <%= f.radio_button :rating, 'positive', :onclick => '$('some_div').show();' %>

Which of the following is the correct syntax for an input field of radio buttons in form_for?

Which of the following is the correct way to rollback a migration?

Which of the following methods is used to check whether an object is valid or invalid?

What is the difference between :dependent => :destroy and :dependent => :delete_all in Rails?