Rails - Aug 2010 - How to simulate a column that do not exists in a model

Hello there..

what i am trying to do, is to consider a new column in my model, a column
that do not exist in the database, and will not be created.

imagine, for instance, this case:

I have a table that store a number and a string, lets call it
''words''

--------------------
words
--------------------
int times(PK)
char name
--------------------

imagine Word as an instance of the model, i will have access to these:
Word.times
Word.name

what if i wanted a new column, some like
Word.complete

imagine that this column would store that ''char'' for many
times as is
defined int the ''times'' column...
like this

Word.times = 3
Word.name = a
Word.complete = aaa

got it?

i wont store that data, but generate it based on the data that is stored.

any idea????

did any of you guys see this situation before???

--
Lucas Franceschi
Desenvolvedor
SGI Sistemas
(049) 9922-3360

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lucas franceschi wrote:
> Word.complete = aaa
Word is the model class - it doesn''t store values.

If word is an instance, simply write:

   word[:complete] = aaa
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you didn''t get it...

the point is.. i want

Word.complete

to already be defined, so that in the controller i could use the
"complete"
column as if it was a real column...
--
Lucas Franceschi
Desenvolvedor
SGI Sistemas
(049) 9922-3360



On Tue, Aug 31, 2010 at 4:01 PM, Fritz Trapper
<lists-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org> wrote:
> lucas franceschi wrote:
> > Word.complete = aaa
>
> Word is the model class - it doesn''t store values.
>
> If word is an instance, simply write:
>
>   word[:complete] = aaa
> --
> Posted via http://www.ruby-forum.com/.
>
> --
> You received this message because you are subscribed to the Google Groups
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On 31 August 2010 19:48, lucas franceschi
<lukas1596-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Word.times = 3
> Word.name = a
> Word.complete = aaa
> got it?
> i wont store that data, but generate it based on the data that is stored.
> any idea????
> did any of you guys see this situation before???
once or twice...

what you''re after is a "method"...

(you may run into trouble if you try to call your column
''times'', I''ll
use ''times_repeated'' in this example)

# word.rb
def complete
  self.name * self.times_repeated if self.name
end

I recommend going through some Ruby tutorials - the "Ruby for Rails"
book has a good coverage of getting started through to intermediate
use.

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correction - you will need to check that both name and times_repeated
are not nil

 def complete
  self.name * self.times_repeated if self.name && self.times_repeated
 end

strictly speaking the "self." isn''t needed either, but it
does make
the intention clearer...

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just look up attr_accessor method, if used within a model on a non
existant field in the model, it will create a "pseudo" field. Do not
forget to make accessible.

On Sep 1, 12:11 am, Michael Pavling
<pavl...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> correction - you will need to check that both name and times_repeated
> are not nil
>
>  def complete
>   self.name * self.times_repeated if self.name &&
self.times_repeated
>  end
>
> strictly speaking the "self." isn''t needed either, but
it does make
> the intention clearer...
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