Rails - Aug 2005 - ActiveRecord Limitations?

I''m building my first RoR app and am trying to grasp the limitations
of ActiveRecord, i.e. when does the "magic" breakdown. I''m a
ASP.net
developer (with a string DB background) by trade and am pumped about
the productivity increases the RoR may offer. I''m a bit concerned
about getting "stuck" on certain areas that would be fairly simple to
solve with .NET, not because RoR can''t solve them, but due to my
current lack of knowledge of the Rails stack (and Ruby for that
matter).

On to the problem at hand. How would one do the following with ActiveRecord?

I have a site that is managing advertisers in a publication. Each
issue of the publication has certain advertisers. An advertisers is
assigned a specific advertiser index in each issue. This index could
change from issue to issue. It is very close to a many-to-many join
with the exception of the advertiser index. Since it''s not a straight
many to many join, how would I utilize ActiveRecord?

**DATABASE**

CREATE TABLE `advertiser` (
  `id` int(10) unsigned NOT NULL auto_increment,
  `name` varchar(200) NOT NULL default '''',
  `notes` varchar(255) NOT NULL default '''',
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 

CREATE TABLE `issue` (
  `id` int(10) unsigned NOT NULL auto_increment,
  `name` varchar(45) NOT NULL default '''',
  `publish_date` date NOT NULL default ''0000-00-00'',
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

CREATE TABLE `issue_advertisers` (
  `issue_id` int(11) NOT NULL default ''0'',
  `advertiser_index` int(11) NOT NULL default ''0'',
  `advertiser_id` int(11) NOT NULL default ''0'',
  PRIMARY KEY  (`issue_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

Thanks for any help.

--Ryan

Ryan Wood <ryan.wood-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> writes:
> I have a site that is managing advertisers in a publication. Each
> issue of the publication has certain advertisers. An advertisers is
> assigned a specific advertiser index in each issue. This index could
> change from issue to issue. It is very close to a many-to-many join
> with the exception of the advertiser index. Since it''s not a
straight
> many to many join, how would I utilize ActiveRecord?
>
> **DATABASE**
>
> CREATE TABLE `advertiser` (
For better or worse, the "golden path" of Rails development is to use
plural names on tables.  You can turn this off, but I personally don''t
recommend it.  Name this table ''advertisers'' and the one below
''issues''.
>   `id` int(10) unsigned NOT NULL auto_increment,
>   `name` varchar(200) NOT NULL default '''',
>   `notes` varchar(255) NOT NULL default '''',
>   PRIMARY KEY  (`id`)
> ) ENGINE=InnoDB DEFAULT CHARSET=latin1 
>
> CREATE TABLE `issue` (
>   `id` int(10) unsigned NOT NULL auto_increment,
>   `name` varchar(45) NOT NULL default '''',
>   `publish_date` date NOT NULL default ''0000-00-00'',
One thing to think about, if you have a column named
''create_at'' then
ActiveRecord will automatically record when the issue is first
created.  Probably not the same thing as publish_date, but something
to think about.
>   PRIMARY KEY  (`id`)
> ) ENGINE=InnoDB DEFAULT CHARSET=latin1
>
> CREATE TABLE `issue_advertisers` (
Join tables need to be in alphabetical order.  This should be
''advertisers_issues''.
>   `issue_id` int(11) NOT NULL default ''0'',
>   `advertiser_index` int(11) NOT NULL default ''0'',
>   `advertiser_id` int(11) NOT NULL default ''0'',
>   PRIMARY KEY  (`issue_id`)
> ) ENGINE=InnoDB DEFAULT CHARSET=latin1
class Advertiser < ActiveRecord::Base
  has_and_belongs_to_many :issues
end

class Issue < ActiveRecord::Base
  has_and_belongs_to_many :advertisers
end

Note that you''ll need to use something like
@issue.advertisers.push_with_attributes(@attribute, {:advertiser_index
=> "foo" }) to get attributes on the join table.  However, if you
start getting too many join attributes or need to modify them much, it
may be easier to do this:


class AdvertiserIssue < ActiveRecord::Base
  belongs_to :advertiser
  belongs_to :issue
end

class Advertiser < ActiveRecord::Base
  has_many :advertiser_issues
end

class Issue < ActiveRecord::Base
  has_many :advertiser_issues
end


-- 
doug-jGAhs73c5XxeoWH0uzbU5w@public.gmane.org