issue tracker
forum
source
rubyforge
rubydoc

defaults

Doodle assumes that attributes specified without defaults or initial values are required. If you try to initialize an instance without providing values for all required attributes, Doodle will raise an exception. For example:

class Event < Doodle
  has :date
end

event = Event()
# or
event = Event.new

will result in:

Event missing required attribute 'date' (Doodle::ValidationError)

To specify a default, use the default option:

class Event < Doodle
  has :date, :default => Date.today
end

Now we can create an Event without specifying a date:

event = Event()
 => #<Event:0x71343c>
event.date
 => #<Date: 4909061/2,0,2299161>

You can of course override the default on initialization or later:

event = Event(:date => Date.new(2008, 03, 01))
 => #<Event:0x7036e0 @date=#<Date: 4909053/2,0,2299161>>
event.date = Date.new(2008, 03, 05)
 => #<Date: 4909061/2,0,2299161>

Note that if you do not specify a value for an attribute with a default, no instance variable is created.

dynamically calculated defaults

With the default specified as above, the date attribute will take on the value current when the class is defined. If you want the default value to be recalculated every time, use a Proc object or block as the default value.

class Event < Doodle
  has :time, :default => proc { Time.now }
end
# or
class Event < Doodle
  has :time do
    default { Time.now }
  end
end

event.time
 => Wed Mar 05 14:44:01 +0000 2008
event.time
 => Wed Mar 05 14:44:03 +0000 2008

dependent attributes

Dynamically calculating an attribute value can be quite useful when you have dependent attributes, as in this example:

class Event < Doodle
  has :start_date, :default => Date.today
  has :end_date, :default => proc { start_date + 1 }
end

event.start_date.to_s
=> "2008-03-05"
event.end_date.to_s
=> "2008-03-06"