Boolean database + Site Design/Architecture Question

rubyonrails-talk
1

Hi all,

As usual, you've all been very helpful in the past and I thank you for continuing to help myself and others.

Today I have the following code/database architecture question which I would like you guys to help me out with.

Children Table (user has_many children)

2

I would go with a single 'status' field.

3

Roy Pardee wrote:

I would go with a single 'status' field.

Thanks Roy, I appreciate the reply. I guess I could just do a...

[code] if @child.status == 'lost'   ... [/code]

I did like the elegance of boolean for things like:

[code] if @child.is_lost?   ... [/code]

Any other suggestions or opinions?

4

Well, you can still have those is_whatever? methods--just write them on the model your own self:

class Child   def is_lost?     self.status == 'lost'   end   def is_found?     self.status == 'found'   end   def is_safe?     self.status = 'safe'   end end

You could even write your own setters (def is_safe=(new_val)), tho that may be taking it too far...

5

Roy Pardee wrote:

Well, you can still have those is_whatever? methods--just write them on the model your own self:

Touché. Can't believe I didn't think about that! Thank you!!

6

First and foremost, shouldn't your model be called Child? A single child shouldn't be called "a children", but that's how you have it set up. Having it as is won't destroy the universe, but it will end up getting really confusing sooner or later. Rails knows that "children" is the plural form of "child". Open the rails console and type "child".pluralize to see for yourself.

That aside, since Children is a stateful object, you should consider the Acts As State Machine plugin. All you need is the plugin and a "state" (varchar) column in the model's database table. This gives you all kinds of neat functionality.

In your rails app root, do this little number: script/plugin install http://elitists.textdriven.com/svn/plugins/acts_as_state_machine/trunk/

We will configure your model to have three states: "safe", "lost", and "found". In your Children model, add the following:

#set the default state acts_as_state_machine, :initial => :safe

# declare three states: "safe", "lost", and "found" state :safe state :lost state :found

# configure state methods event :lost do
  transitions :from => :safe, :to => :lost   transitions :from => :found, :to => :lost end event :found do
  transitions :from => :safe, :to => :found   transitions :from => :lost, :to => :found end event :safe do
  transitions :from => :lost, :to => :safe   transitions :from => :found, :to => :safe end

That's it. Now the following methods will work to check the state: @child.safe? # true/false @child.lost? # true/false @child.found? # true/false

The "events" that you declared are used to change the object's state, using event!. For example, to change a safe child to lost, you would call: @child.lost! Normally, you would want to name your "events" some kind of verb. This makes the method easier to read and understand, but your situation is peculiar. I guess you should leave them as is to avoid any further confusion.

You can tell AASM to call additional methods when transitioning between states, if you wish. You can also block transitions unless certain conditions are met. Read up on the callbacks and guard functions here: http://rails.aizatto.com/2007/05/24/ruby-on-rails-finite-state-machine-plugin-acts_as_state_machine/ (site is currently showing a blank page, but it's there, I swear!)

7

I hate to bump and annoy, but can anyone offer a suggestion on my last reply?

Thanks!

-Tony