Rails - Aug 2009 - Can non-ActiveRecord variables be temporarily stored in a class?

I''m creating a PDF directory using PDF::Writer.

The directory has a few pieces.
* The photo directory is sorted by group
* The appendix is sorted by last name

I want the appendix to show the page number on which the person is
printed, but I don''t want to store that in the database.


I would like to do this:
contact.page_number = page_number
contacts << contact


but currently I''m doing this
tuple[:contact => contact, :page_number => page_number]
contacts << tuple

> > The directory has a few pieces.
> > * The photo directory is sorted by group
> > * The appendix is sorted by last name
>
> > I want the appendix to show the page number on which the person is
> > printed, but I don''t want to store that in the database.
>
> An activerecord object is a normal ruby object - it can have non
> database store instance variables if you want.
but when I do this:
contact.page_number = page_number
where page_number doesn''t exist in db/migrate/001_create_contacts.rb
or app/model/contacts.rb
I get this:
undefined method `page_number='' for #<Contact:0xb6bbb5b4>

On Aug 25, 6:38 pm, CoolAJ86
<coola...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> > > The directory has a few pieces.
> > > * The photo directory is sorted by group
> > > * The appendix is sorted by last name
>
> > > I want the appendix to show the page number on which the person
is
> > > printed, but I don''t want to store that in the database.
>
> > An activerecord object is a normal ruby object - it can have non
> > database store instance variables if you want.
>
> but when I do this:
> contact.page_number = page_number
Well yes - you still need to write the accessor methods to store you
instance variables (attr_accessor is probably enough).

Fred
> where page_number doesn''t exist in
db/migrate/001_create_contacts.rb
> or app/model/contacts.rb
> I get this:
> undefined method `page_number='' for #<Contact:0xb6bbb5b4>

> Well yes - you still need to write the accessor methods to store you
> instance variables (attr_accessor is probably enough).
>
> Fred
That makes sense. Thanks.

I had my JavaScript thinking cap on when I was doing this... thinking
to create accessors out of thin air.

I also just found out that the virtual accessors are accessors, not
class variables.
return @updated_at # always null
return updated_at # works

2009/8/30 CoolAJ86
<coolaj86-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>
>> Well yes - you still need to write the accessor methods to store you
>> instance variables (attr_accessor is probably enough).
>>
>> Fred
>
> That makes sense. Thanks.
>
> I had my JavaScript thinking cap on when I was doing this... thinking
> to create accessors out of thin air.
>
> I also just found out that the virtual accessors are accessors, not
> class variables.
> return @updated_at # always null
> return updated_at # works
Don''t understand this.
As I understand it if you have
attr_accessor :my_var
then @my_var will access the variable (but this may only be written
inside the class)
and my_var is a method (well two methods actually) that may be used
externally to read/write to @my_var so you can say
my_object.my_var = 1
x = my_object.my_var

If you use my_var (no @) inside the class this should work but it is
calling the accessor methods rather than directly accessing @my_var

Colin

2009/8/30 Frederick Cheung
<frederick.cheung-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>
>
> On 30 Aug 2009, at 09:17, Colin Law wrote:
>
>>
>> 2009/8/30 CoolAJ86
<coolaj86-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>>>
>>>> Well yes - you still need to write the accessor methods to
store you
>>>> instance variables (attr_accessor is probably enough).
>>>>
>>>> Fred
>>>
>>> That makes sense. Thanks.
>>>
>>> I had my JavaScript thinking cap on when I was doing this...
thinking
>>> to create accessors out of thin air.
>>>
>>> I also just found out that the virtual accessors are accessors, not
>>> class variables.
>>> return @updated_at # always null
>>> return updated_at # works
>>
>> Don''t understand this.
>
> I think what the previous poster has realised is that activerecord
> attributes are not stored inside individual instance variables.
Ah, yes

Colin
>
> Fred
>> As I understand it if you have
>> attr_accessor :my_var
>> then @my_var will access the variable (but this may only be written
>> inside the class)
>> and my_var is a method (well two methods actually) that may be used
>> externally to read/write to @my_var so you can say
>> my_object.my_var = 1
>> x = my_object.my_var
>>
>> If you use my_var (no @) inside the class this should work but it is
>> calling the accessor methods rather than directly accessing @my_var
>>
>> Colin
>>
>> >
>
>
> >
>

Maybe this is useful

http://forums.site5.com/showthread.php?t=18522

On 30 авг, 06:44, Colin Law
<clan...-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org>
wrote:
> 2009/8/30 Frederick Cheung
<frederick.che...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>
>
>
>
>
> > On 30 Aug 2009, at 09:17, Colin Law wrote:
>
> >> 2009/8/30 CoolAJ86
<coola...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>
> >>>> Well yes - you still need to write the accessor methods to
store you
> >>>> instance variables (attr_accessor is probably enough).
>
> >>>> Fred
>
> >>> That makes sense. Thanks.
>
> >>> I had my JavaScript thinking cap on when I was doing this...
thinking
> >>> to create accessors out of thin air.
>
> >>> I also just found out that the virtual accessors are
accessors, not
> >>> class variables.
> >>> return @updated_at # always null
> >>> return updated_at # works
>
> >> Don''t understand this.
>
> > I think what the previous poster has realised is that activerecord
> > attributes are not stored inside individual instance variables.
>
> Ah, yes
>
> Colin
>
>
>
> > Fred
> >> As I understand it if you have
> >> attr_accessor :my_var
> >> then @my_var will access the variable (but this may only be
written
> >> inside the class)
> >> and my_var is a method (well two methods actually) that may be
used
> >> externally to read/write to @my_var so you can say
> >> my_object.my_var = 1
> >> x = my_object.my_var
>
> >> If you use my_var (no @) inside the class this should work but it
is
> >> calling the accessor methods rather than directly accessing
@my_var
>
> >> Colin