Robert Walker wrote in post #978350:
> Robert Walker wrote in post #978348:
>> Here's one way that could be accomplished:
>>
>> The jobs table
>> +----+------------+------------+-----+
>> | id | creator_id | checker_id | ... |
>> | 1 | 3 | 7 | ... |
>> | 2 | 1 | 4 | ... |
>> +----+------------+------------+-----+
>
> Also note that this technique does not conform to the First Normal Form
> (1NF) of database design.
How do you figure that? It looks well normalized to me. creator_id and
checker_id aren't really a repeating group.
> An alternative normalized approach would
> involve associating Job and Worker though a many-to-many association and
> tagging the worker with a role in the join table.
>
> the job_workers join table
> +----+--------+-----------+-------------+
> | id | job_id | worker_id | role |
> | 1 | 1 | 3 | creator |
> | 2 | 1 | 7 | checker |
> | 3 | 2 | 1 | creator |
> | 4 | 2 | 4 | checker |
> +----+--------+-----------+-------------+
This is actually less normalized in the sense that you're repeating the
role name. But that's a quibble. :)
However, whether or not it's more normalized, I do agree that the latter
approach is the more flexible.
>
> Job < AR
> has_many :job_workers
> has_many :workers, :through => :job_workers
> end
>
> JobWorker < AR
> belongs_to :job
> belongs_to :worker
> end
Don't call it JobWorker! Join models should have descriptive names.
How about Assignment?
>
> Worker < AR
> has_many :job_workers
> has_many :jobs, :through => :job_workers
> end
>
> job_1 = Job.find(1)
> job_2 = Job.find(2)
>
> puts job_1.job_workers.each { |jw| puts "#{jw.worker_id }
> :#{jw.worker_role}" }
> => 3 : creator
> => 7 : checker
>
> puts job_2.job_workers.each { |jw| puts "#{jw.worker_id} :
> #{jw.worker_role}" }
> => 1 : creator
> => 4 : checker
Best,
--
Marnen Laibow-Koser
http://www.marnen.org
[email protected]
Sent from my iPhone
--
Posted via http://www.ruby-forum.com/.
--
You received this message because you are subscribed to the Google Groups "Ruby
on Rails: Talk" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en.
