Rails - Mar 2006 - attribute or instance method or what?

Hi!

Uhm are attributes just something like additional members of a class, 
other than those that come from the names of columns in the table?

I''ve got images table, which has ''name'' column.
I''ve added support for
creating thumbnails out of uploaded pictures and i''d like to have an 
easy way of accessing them in my views.

How to do it? I.e. my image has name ''1-13.jpg'' and thumbnail
will have
''1-13-thumb.jpg''. Do i have to create additional attribute
thumbnailname
and somehow set it automatically based on ''name'' value, so it
will be
available for an instance variable of my image class, or create a helper 
method for image class or...?

-- 
Posted via http://www.ruby-forum.com/.

Cze?? Szymek :)

On 08/03/06, szymek <g0nzo@o2.pl> wrote:
> How to do it? I.e. my image has name ''1-13.jpg'' and
thumbnail will have
> ''1-13-thumb.jpg''. Do i have to create additional
attribute thumbnailname
> and somehow set it automatically based on ''name'' value,
so it will be
> available for an instance variable of my image class, or create a helper
> method for image class or...?
The simpliest way would be to provide additional getter:

class Image
  def thumbnail_name
    self.name.gsub(/\.jpg$/, ''-thumb.jpg'')
  end
end

--
?ukasz Piestrzeniewicz
http://ragnarson.blogspot.com

On Mar 8, 2006, at 10:19, ?ukasz Piestrzeniewicz wrote:
> Cze?? Szymek :)
>
> On 08/03/06, szymek <g0nzo@o2.pl> wrote:
>> How to do it? I.e. my image has name ''1-13.jpg'' and
thumbnail will
>> have
>> ''1-13-thumb.jpg''. Do i have to create additional
attribute
>> thumbnailname
>> and somehow set it automatically based on ''name''
value, so it will be
>> available for an instance variable of my image class, or create a  
>> helper
>> method for image class or...?
>
> The simpliest way would be to provide additional getter:
>
> class Image
>   def thumbnail_name
>
>   end
> end
And if you needed the thumbnail name in SQL land as well then write a  
custom name setter that delegates to AR this way:

   class Image < ActiveRecord::Base
     def name=(n)
       write_attribute(:name, n)
       write_attribute(:thumbnail_name, n.gsub(/\.jpg$/,
''-thumb.jpg''))
     end
   end

-- fxn

Czesc!

Dzieki za odpowiedz!... i mean, thanks for your answer :)

Previously i had name2thumbname as class method. Now i''ve changed 
everything to instance methods and it works great, but i''ve got one
more
question:

I''m adding new images to the database like this (in a loop):
@property.images << Image.new(:image_url => image_filename)

Is it possible to get id of new image without searching for it in the 
database? Maybe << method returns new id?

Because since i''ve changed everything to instance methods now i add the
image to the database and in the next line i search for it by the 
filename to get its instance. It works, but maybe there''s a better way.

-- 
Posted via http://www.ruby-forum.com/.