thr3ads.net - Rails - Boolean database + Site Design/Architecture Question [Oct 2008]

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Tony Tony

2008-Oct-21 19:58 UTC

Boolean database + Site Design/Architecture Question

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)
--------------
...
is_lost boolean, default => false
is_found boolean, default => false
...


Basically, a child is "safe" if he is not flagged as lost or found (so
a
child has 3 possible states: safe, lost, found).

I created a custom validation to avoid a child from being both lost AND
found with this:

[code]
def validate
if is_lost? and is_found?
      errors.add_to_base("A child can''t be lost
<i>AND</i> found at the
same time!")
    end
end
[/code]

This all works great and validates correctly. HOWEVER, the only way
I''ve
been able to select if a child is lost or found is through check boxes
(not the best way to do this). I think a drop down box would be the
better solution to select if a child is either lost or found (or safe)


My question is this:

Is this the best way to achieve what I am trying to do? Is it better to
just have a column in my table named "status" where the values would
be
either Safe, Lost, Found and remove the is_lost and is_found boolean
columns instead?

If the current way I designed it is good, how can I create a drop down
box that could handle both the is_lost and is_found data?


I know this is a disaster (in my eyes) but I would like the opinions and
suggestions of you experienced folks.


Thank you!!!
-Tony


P.S.  Let me know if you need more info or code to help you understand
this.
-- 
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Pardee, Roy

2008-Oct-21 20:04 UTC

head link

Re: Boolean database + Site Design/Architecture Question

I would go with a single ''status'' field.

-----Original Message-----
From: rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
[mailto:rubyonrails-talk@googlegroups.com] On Behalf Of Tony Tony
Sent: Tuesday, October 21, 2008 12:59 PM
To: rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
Subject: [Rails] Boolean database + Site Design/Architecture Question

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)
--------------
...
is_lost boolean, default => false
is_found boolean, default => false
...

Basically, a child is "safe" if he is not flagged as lost or found (so
a child has 3 possible states: safe, lost, found).

I created a custom validation to avoid a child from being both lost AND found
with this:

[code]
def validate
if is_lost? and is_found?
      errors.add_to_base("A child can''t be lost
<i>AND</i> found at the same time!")
    end
end
[/code]

This all works great and validates correctly. HOWEVER, the only way
I''ve been able to select if a child is lost or found is through check
boxes (not the best way to do this). I think a drop down box would be the better
solution to select if a child is either lost or found (or safe)

My question is this:

Is this the best way to achieve what I am trying to do? Is it better to just
have a column in my table named "status" where the values would be
either Safe, Lost, Found and remove the is_lost and is_found boolean columns
instead?

If the current way I designed it is good, how can I create a drop down box that
could handle both the is_lost and is_found data?

I know this is a disaster (in my eyes) but I would like the opinions and
suggestions of you experienced folks.

Thank you!!!
-Tony

P.S.  Let me know if you need more info or code to help you understand this.
--
Posted via http://www.ruby-forum.com/.

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Tony Tony

2008-Oct-21 20:12 UTC

head link

Re: Boolean database + Site Design/Architecture Question

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?
-- 
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Pardee, Roy

2008-Oct-21 20:20 UTC

head link

Re: Boolean database + Site Design/Architecture Question

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...

-----Original Message-----
From: rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
[mailto:rubyonrails-talk@googlegroups.com] On Behalf Of Tony Tony
Sent: Tuesday, October 21, 2008 1:13 PM
To: rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
Subject: [Rails] Re: Boolean database + Site Design/Architecture Question


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?
--
Posted via http://www.ruby-forum.com/.



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Tony Tony

2008-Oct-21 20:36 UTC

head link

Re: Boolean database + Site Design/Architecture Question

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!!
-- 
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Patrick Sullivan

2008-Oct-21 22:03 UTC

head link

Re: Boolean database + Site Design/Architecture Question

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!)

On Tuesday October 21, 2008 2:58:40 pm Tony Tony wrote:> 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)
> --------------
> ...
> is_lost boolean, default => false
> is_found boolean, default => false
> ...
>
>
> Basically, a child is "safe" if he is not flagged as lost or
found (so a
> child has 3 possible states: safe, lost, found).
>
> I created a custom validation to avoid a child from being both lost AND
> found with this:
>
> [code]
> def validate
> if is_lost? and is_found?
>       errors.add_to_base("A child can''t be lost
<i>AND</i> found at the
> same time!")
>     end
> end
> [/code]
>
> This all works great and validates correctly. HOWEVER, the only way
I''ve
> been able to select if a child is lost or found is through check boxes
> (not the best way to do this). I think a drop down box would be the
> better solution to select if a child is either lost or found (or safe)
>
>
> My question is this:
>
> Is this the best way to achieve what I am trying to do? Is it better to
> just have a column in my table named "status" where the values
would be
> either Safe, Lost, Found and remove the is_lost and is_found boolean
> columns instead?
>
> If the current way I designed it is good, how can I create a drop down
> box that could handle both the is_lost and is_found data?
>
>
> I know this is a disaster (in my eyes) but I would like the opinions and
> suggestions of you experienced folks.
>
>
> Thank you!!!
> -Tony
>
>
> P.S.  Let me know if you need more info or code to help you understand
> this.

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Tony Tony

2008-Oct-22 04:19 UTC

head link

Re: Boolean database + Site Design/Architecture Question

Patrick Sullivan wrote:
> 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.
> 

Thank you immensely for bring that plugin to my attention. As for the 
child naming, I''m using pseudo code for the most part. Sorry about
that.

I just have a (silly) question about the event! calls... where do I put 
them? :) I tried searching for it but didn''t find an exact answer.

I was able to make the state column into a drop box with the three 
states like so (in a hurry):

[code]
<%= select :child, :state, { "Safe" => "safe",
"Lost" => "lost", "Found"
=> "found"}  %>
[/code]

So it updates and displays the state just fine (@child.state). HOWEVER, 
I''m sure the use of @child.lost!, @child.found!, and @child.safe! is 
there for a reason. What is the best way to go about implementing this?

From just some quick brainstorming I''m thinking the below if block in 
the update (and create) method would work, but perhaps there is a better 
way?

[code]
def update
    @child = Children.find(params[:id])

    if params[:state]==''lost''
      @child.lost!
    elsif params[:state]==''found''
      @child.found!
    else
      @child.safe!
    end

...
end
[/code]

Also, is it possible to use more than one act_as_state_machine per 
model? I''m assuming you can by assigning a :column =>
''column_name''. But
confirmation would be nice.

Thank you so much again!!!
-Tony
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Tony Tony

2008-Oct-23 14:05 UTC

head link

Re: Boolean database + Site Design/Architecture Question

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

Thanks!

-Tony
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Rails - Oct 2008 - Boolean database + Site Design/Architecture Question

Boolean database + Site Design/Architecture Question

Re: Boolean database + Site Design/Architecture Question

Re: Boolean database + Site Design/Architecture Question

Re: Boolean database + Site Design/Architecture Question

Re: Boolean database + Site Design/Architecture Question

Re: Boolean database + Site Design/Architecture Question

Re: Boolean database + Site Design/Architecture Question

Re: Boolean database + Site Design/Architecture Question