# Idiomatic way to do a non-database Enumeration?

**URL:** <https://www.ruby-forum.com/t/idiomatic-way-to-do-a-non-database-enumeration/112852>\
**Category:** Rails\
**Created:** [August 23, 2007, 9:38pm UTC](https://www.ruby-forum.com/t/idiomatic-way-to-do-a-non-database-enumeration/112852 "2007-08-23T21:38:52Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Zeekar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/a8b319/32.png) [@Zeekar](https://www.ruby-forum.com/u/Zeekar)\
**Post date:** [August 23, 2007, 9:38pm UTC](https://www.ruby-forum.com/t/idiomatic-way-to-do-a-non-database-enumeration/112852/1 "2007-08-23T21:38:52Z")

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I have a class which stores as one of its attributes a day of the week  
as an integer (0-6, 0=Sunday, standard UNIXy values). I want,  
obviously, the views to show the weekday name and the forms to provide  
a drop-down with the weekday names. Essentially it’s a vrtual  
attribute whose value is the localized weekday name, which maps to the  
integer value that’s actually stored.

There are a lot of approaches, but I was wondering what the idiomatic  
Rails-y way of doing it is. Should I create a Weekday class? It  
wouldn’t be backed by the db - that’s not localizable or DRY…

Any help appreciated.

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**Author:** ![Zeekar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/a8b319/32.png) [@Zeekar](https://www.ruby-forum.com/u/Zeekar)\
**Post date:** [August 23, 2007, 9:51pm UTC](https://www.ruby-forum.com/t/idiomatic-way-to-do-a-non-database-enumeration/112852/2 "2007-08-23T21:51:54Z")

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On Thu, Aug 23, 2007 at 07:38:27PM -0000, Zeekar wrote:

> I have a class which stores as one of its attributes a day of the week  
> as an integer (0-6, 0=Sunday, standard UNIXy values). I want,  
> obviously, the views to show the weekday name and the forms to provide  
> a drop-down with the weekday names. Essentially it’s a vrtual  
> attribute whose value is the localized weekday name, which maps to the  
> integer value that’s actually stored.

There are two pieces to this. One is how you deal with the data readably  
in  
your code, the other is rendering a localized version.

> There are a lot of approaches, but I was wondering what the idiomatic  
> Rails-y way of doing it is. Should I create a Weekday class? It  
> wouldn’t be backed by the db - that’s not localizable or DRY…

In your code, the idiomatic way is to use an array:

DAYS = %w(sunday monday tuesday wednesday thursday friday saturday)

You should override your accessors that otherwise return a number 0-6 to  
instead return that DAYS[value] (or, more likely, value && DAYS[value]).  
Now you can deal with days by string. (Probably a better choice is to  
make  
that an array of symbols and deal with them by symbol.) Once you get to  
the  
rendering phase, just have your local substitutions based on the  
internal  
symbols.

> Any help appreciated.  
> –Greg

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<div class="post-metadata">

**Author:** ![Zeekar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/a8b319/32.png) [@Zeekar](https://www.ruby-forum.com/u/Zeekar)\
**Post date:** [August 23, 2007, 10:07pm UTC](https://www.ruby-forum.com/t/idiomatic-way-to-do-a-non-database-enumeration/112852/3 "2007-08-23T22:07:56Z")

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I’ve done a similar thing with Periods of time ( e.g. daily, weekly,  
monthly ) where I wanted the value stored as an integer number of days.  
To do this I created a Struct for Period and then set a constant  
pointing to a hash of populated Periods.

hth,  
-jc

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<div class="post-metadata">

**Author:** ![Zeekar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/a8b319/32.png) [@Zeekar](https://www.ruby-forum.com/u/Zeekar)\
**Post date:** [August 24, 2007, 2:52am UTC](https://www.ruby-forum.com/t/idiomatic-way-to-do-a-non-database-enumeration/112852/4 "2007-08-24T02:52:25Z")

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Ok, for the display I made a new FormBuilder subclass and added a  
select\_weekday method. To get the localized weekday names, it does  
this:

Date.new(2001,1,weekday\_number+7).strftime("%A")

Someone please tell me a better way. 🙂

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<div class="post-metadata">

**Author:** ![Zeekar](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/a8b319/32.png) [@Zeekar](https://www.ruby-forum.com/u/Zeekar)\
**Post date:** [August 24, 2007, 7:10pm UTC](https://www.ruby-forum.com/t/idiomatic-way-to-do-a-non-database-enumeration/112852/5 "2007-08-24T19:10:32Z")

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It seems that Date#strftime doesn’t honor locale settings, which is  
odd since strftime(3) does. So that code returns the same output as  
just doing Date::DAYNAMES[weekday\_number]. I’ll have to look into  
some other way to get at the localized names…