Rails - Sep 2008 - Custom Sort - Possible?

Hi all,

I''m working on a help system that lets users assign a "tag
color" to
their requests in addition to assigning the usual "high, medium, low"
priority.  My question is whether it''s possible to do a sort based on
the tag color.  Valid colors are green, yellow, orange, and red, and
these are stored as strings in the database.

I''d like to use something like:

# Customer Model
has_many :requests, :order => priority, tag_color

Is it possible to add a sort based on these string values?

Thanks!
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> I''m working on a help system that lets users assign a "tag
color" to
> their requests in addition to assigning the usual "high, medium,
low"
> priority.  My question is whether it''s possible to do a sort based
on
> the tag color.  Valid colors are green, yellow, orange, and red, and
> these are stored as strings in the database.
>
> I''d like to use something like:
>
> # Customer Model
> has_many :requests, :order => priority, tag_color
That will sort them alphabetically, probably not what you want.

If there is an order those colors you could do something like this:

:order => "priority, tag_color = ''red'', tag_color =
''orange'',
tag_color = ''yellow'', tag_color =
''green''"

With an optional "DESC" thrown in to each of those.  Basically that  
converts your order by clause into a series of booleans and sorts that  
way.  Little ugly, but it will work.

-philip

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You could also put a method like this in your Request model

def Request.sql_tag_color_order
  ''(CASE requests.tag_color WHEN ''red'' THEN 1 WHEN
''yellow'' THEN 2
WHEN ''green'' THEN 3 ELSE 4 END)''
end

Then change the line in your Customer model to
has_many :requests, :order => "priority,
#{Request.sql_tag_color_order}"

That way when you want to order requests in another part of your
application you can use Request.sql_tag_color_order instead of having
to repeat the transformation from text to something order.

HTH

Neal L wrote:
> Hi all,
>
> I''m working on a help system that lets users assign a "tag
color" to
> their requests in addition to assigning the usual "high, medium,
low"
> priority.  My question is whether it''s possible to do a sort based
on
> the tag color.  Valid colors are green, yellow, orange, and red, and
> these are stored as strings in the database.
>
> I''d like to use something like:
>
> # Customer Model
> has_many :requests, :order => priority, tag_color
>
> Is it possible to add a sort based on these string values?
>
> Thanks!
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