If you observe your rails app, you might come across some set of values constantly being used. It is a good idea to identify them and dry them up. For example, in the models, you might have used a Regular expression for checking the validity of email attribute.
in app/models/account.rb
validates_format_of :email,:with => /(^([^,@\s]+)@((?:[-_a-z0-9]+\.)+[a-z]{2,})$)|(^$)/i
in app/models/delegate.rb
validates_format_of :email,:with => /(^([^,@\s]+)@((?:[-_a-z0-9]+\.)+[a-z]{2,})$)|(^$)/i
Don’t you see, its very hard to keep using it across models or any other ruby files. For this, We can create a file called constants.rb in config/initializers and declare a constant (with a good, rememberable name) there.
In config/initializers/constants.rb
EMAIL_REGEXP = /(^([^,@\s]+)@((?:[-_a-z0-9]+\.)+[a-z]{2,})$)|(^$)/i
Restart the server now. Then in the model file shown above, we can use it like
validates_format_of :email,:with => EMAIL_REGEXP
We can use the same technique with other constant values that are used more than once in the application.
Tags: programming, rails, refactoring, ruby
