# Design question - where to store constants?

**URL:** <https://www.ruby-forum.com/t/design-question-where-to-store-constants/66236>\
**Category:** Rails\
**Created:** [February 12, 2006, 10:11pm UTC](https://www.ruby-forum.com/t/design-question-where-to-store-constants/66236 "2006-02-12T22:11:33Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![janovetz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/53a042/32.png) [@janovetz](https://www.ruby-forum.com/u/janovetz)\
**Post date:** [February 12, 2006, 10:11pm UTC](https://www.ruby-forum.com/t/design-question-where-to-store-constants/66236/1 "2006-02-12T22:11:33Z")

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Let’s say I create a “ticket system” that has a support ticket with a  
status attached to it. (Say, OPEN or CLOSED for now, but more later)

The status -could- be another table in the database listing status  
types, but I think that’s unnecessarily complex and overly flexible for  
this. (opinions on this point would be interesting)

Another alternative would be to define the statuses as a constant within  
the application:

ticket\_status = [“Open”, “Closed”]

Where is this constant declaration best suited? At the App level in the  
CONFIG[]? Or in the model for the ticket? The controller for the  
ticket? It seems to be a model thing.

Jake

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<div class="post-metadata">

**Author:** ![janovetz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/53a042/32.png) [@janovetz](https://www.ruby-forum.com/u/janovetz)\
**Post date:** [February 12, 2006, 10:15pm UTC](https://www.ruby-forum.com/t/design-question-where-to-store-constants/66236/2 "2006-02-12T22:15:51Z")

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Jake J. wrote:

> Let’s say I create a “ticket system” that has a support ticket with a  
> status attached to it. (Say, OPEN or CLOSED for now, but more later)
> 
> The status -could- be another table in the database listing status  
> types, but I think that’s unnecessarily complex and overly flexible for  
> this. (opinions on this point would be interesting)
> 
> Another alternative would be to define the statuses as a constant within  
> the application:
> 
> ticket\_status = [“Open”, “Closed”]
> 
> Where is this constant declaration best suited? At the App level in the  
> CONFIG[]? Or in the model for the ticket? The controller for the  
> ticket? It seems to be a model thing.
> 
> Jake

You could define it in environment.rb:  
TICKET\_STATUS = [“Open”, “Closed”]

Or in the model, it doesnt really matter.

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<div class="post-metadata">

**Author:** ![janovetz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/53a042/32.png) [@janovetz](https://www.ruby-forum.com/u/janovetz)\
**Post date:** [February 12, 2006, 10:29pm UTC](https://www.ruby-forum.com/t/design-question-where-to-store-constants/66236/3 "2006-02-12T22:29:14Z")

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Hi –

On Sun, 12 Feb 2006, Jake J. wrote:

> ticket\_status = [“Open”, “Closed”]  
> That’s not a constant – do you mean TICKET\_STATUSES or something?  
> (Actually if you have a Ticket class you would probably want a  
> constant just called STATUSES.)

> Where is this constant declaration best suited? At the App level in the  
> CONFIG[]? Or in the model for the ticket? The controller for the  
> ticket? It seems to be a model thing.

I think it’s a model thing. Basically, you’re trying _not_ to have to  
type the list of statuses over again if it’s used in multiple methods.  
So it’s just an abstraction one level up:

class Ticket \< ActiveRecord::Base

```
 STATUSES = %w{ Open Closed } # or whatever :-)

 def check_status
   STATUSES.include?(status)
 end

 def something_else
   # do something else with STATUSES
 end

```

end

No need to stash it further away than this. It makes sense, too, that  
the statuses list would be a class-level resource of Ticket.

David

–  
David A. Black (removed\_email\_address@domain.invalid)  
Ruby Power and Light ([http://www.rubypowerandlight.com](http://www.rubypowerandlight.com))

“Ruby for Rails” chapters now available  
from Manning Early Access Program! [Ruby for Rails](http://www.manning.com/books/black)

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<div class="post-metadata">

**Author:** ![janovetz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/53a042/32.png) [@janovetz](https://www.ruby-forum.com/u/janovetz)\
**Post date:** [February 13, 2006, 2:51am UTC](https://www.ruby-forum.com/t/design-question-where-to-store-constants/66236/4 "2006-02-13T02:51:07Z")

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First of all for this case it’d probably be best just to make it a  
boolean. It’ll lead to natural code, like

if ticket.open?  
…

If you really want to go for string statuses though, David’s code  
looks pretty good. I’d do something like,

class Ticket \< ActiveRecord::Base  
Open= ‘open’  
Closed = ‘closed’  
Statuses = [Open, Closed]

def status\_is?(s)  
status == s  
end  
end

This would lead to the reasonably natural code:  
if ticket.status\_is?(Ticket::Open)  
…

You can then also create an open? method, which just checks the status  
with a default val (open classes make it more fun to write mailing  
list posts 🙂

class Ticket \< ActiveRecord::Base  
def open?  
status\_is?(Open)  
end  
end

The very last thing is that you will want to write a validation:

class Ticket \< ActiveRecord::Base  
def validate  
unless status and Statuses.include?(status)  
errors.add(:status, ‘must be one of the following: ’ +  
Statuses.join(’, ')  
end  
end  
end

Anyway, imo this is all a pretty ugly to solution when it can be  
solved by simply making this field a boolean.

Pat

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<div class="post-metadata">

**Author:** ![janovetz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/53a042/32.png) [@janovetz](https://www.ruby-forum.com/u/janovetz)\
**Post date:** [February 13, 2006, 2:58am UTC](https://www.ruby-forum.com/t/design-question-where-to-store-constants/66236/5 "2006-02-13T02:58:42Z")

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On Sun, 2006-02-12 at 18:50 -0700, Pat M. wrote:

> First of all for this case it’d probably be best just to make it a  
> boolean. It’ll lead to natural code, like
> 
> if ticket.open?  
> …

* * *

OK - I asked the other day and didn’t get a bite so since you mentioned  
it…

I am using a boolean…

Accepted and it stores either a 0 or 1 in postgres which is good.

It displays ‘true’ or ‘false’ on screen and I would much rather have it  
display ‘yes’ or ‘no’

How do I change the display of that boolean? Is there a helper or do I  
have to write it? Can I write it so that I can refer to it again and  
again with other booleans?

Craig

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<div class="post-metadata">

**Author:** ![janovetz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/53a042/32.png) [@janovetz](https://www.ruby-forum.com/u/janovetz)\
**Post date:** [February 13, 2006, 3:25am UTC](https://www.ruby-forum.com/t/design-question-where-to-store-constants/66236/6 "2006-02-13T03:25:14Z")

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Craig W. wrote:

> On Sun, 2006-02-12 at 18:50 -0700, Pat M. wrote:
> 
> > First of all for this case it’d probably be best just to make it a  
> > boolean. It’ll lead to natural code, like
> > 
> > if ticket.open?  
> > …

Well, if open/closed is all I wanted to deal with, yes. We’ll see.

> It displays ‘true’ or ‘false’ on screen and I would much rather have it  
> display ‘yes’ or ‘no’
> 
> How do I change the display of that boolean? Is there a helper or do I  
> have to write it? Can I write it so that I can refer to it again and  
> again with other booleans?

The simplest way would be: ( ticket.open? ? ‘yes’ : ‘no’ )

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<div class="post-metadata">

**Author:** ![janovetz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/53a042/32.png) [@janovetz](https://www.ruby-forum.com/u/janovetz)\
**Post date:** [February 13, 2006, 3:35am UTC](https://www.ruby-forum.com/t/design-question-where-to-store-constants/66236/7 "2006-02-13T03:35:55Z")

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On Mon, 2006-02-13 at 03:25 +0100, Jake J. wrote:

> > It displays ‘true’ or ‘false’ on screen and I would much rather have it  
> > display ‘yes’ or ‘no’
> > 
> > How do I change the display of that boolean? Is there a helper or do I  
> > have to write it? Can I write it so that I can refer to it again and  
> > again with other booleans?
> 
> The simplest way would be: ( ticket.open? ? ‘yes’ : ‘no’ )

* * *

works for me - thanks

Craig