Rails - Jun 2010 - difference between belongs_to and references keyword?

First, I am very new to ruby and rails.  Searching for "references" is
really tough, and so I''ve finally come here.

I''m trying to create a scaffold.  Let''s say a Business and a
School both
can have a single Address (not shared).  In a different case, an Offer
has an OfferType (with just a type_id and description).  Also, a
Business can have many Offers.

(I''ve stripped off most of the unrelated columns, like last_name,
etc...)

I''m wondering (in about this order):

a) Am I doing this right?

b) What the difference would be if I used Address business:belongs_to
user:belongs_to instead of references?

c) Is the Business address:has_one redundant with Address
business:references? If not, what does it do? What about the has_many?

d) Will this generate join tables for me? And I don''t need to specify
xxxxx_id''s anywhere in these relationships?

./script/generate scaffold Business address:has_one offer:has_many
name:string first_name:string

./script/generate scaffold School address:has_one name:string

./script/generate scaffold Address business:references school:references
address1:string

./script/generate scaffold Offer business:references offerType:has_one
start_date:datetime

./script/generate scaffold OfferType image:has_one name:string
description:text

(I''m on Ruby 1.8.7 and Rails 2.3.8.)

Thanks!
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Kevin Hastie wrote:
> a) Am I doing this right?
Apparently not.

Weird.  Is it because I didn''t do polymorphic anywhere that Address now
has a business_id, a credit_card_id and a user_id? Obviously this is no 
good - I''d prefer the Business table to have an address_id, etc.... 
So:

e) Did I do this backwards? Should it be Business address:references (or 
address:belongs_to?) and Address business:has_one?

f) Or should I just drop the :references from Addresses and go from 
there?

g) Is using :references (which I don''t see in many docs/tutorials) just
going to get me in trouble as a beginner?

Thanks again!
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Kevin Hastie wrote:

I guess what I really want is something like this:

class Address< ActiveRecord::Base
  belongs_to :addressable, :polymorphic => true
end

class Business< ActiveRecord::Base
 has_one :address, :as => :addressable
end

class School < ActiveRecord::Base
 has_one :address, :as => :addressable
end

h) I don''t suppose there is a way to do that with the scaffold.  Is 
there a typical set of scaffold options that would map to this?

i) Lastly, I guess I am better off avoiding polymorphism at the 
beginning, huh?  I should just be doing a simple mapping...
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I''ve written a short example about has_many, belongs_to -
http://gist.github.com/425026

has_many, has_one, belongs_to deffinitions goes into model and not in
scaffold. You can use "references" like this: script/generate scaffold
address company:references address:text

but as I mentioned in this discussion
http://railsforum.com/viewtopic.php?id=39325
(look for andain''s posts) I''m running into problems where
views are
generated without appended _id. Maybe I''m just doing something wrong
or just not getting it right ...

Anyway I hope i shed some light on your problem.

On Jun 4, 2:18 am, Kevin Hastie
<li...-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org>
wrote:
> Kevin Hastie wrote:
>
> I guess what I really want is something like this:
>
> class Address< ActiveRecord::Base
>   belongs_to :addressable, :polymorphic => true
> end
>
> class Business< ActiveRecord::Base
>  has_one :address, :as => :addressable
> end
>
> class School < ActiveRecord::Base
>  has_one :address, :as => :addressable
> end
>
> h) I don''t suppose there is a way to do that with the scaffold.
 Is
> there a typical set of scaffold options that would map to this?
>
> i) Lastly, I guess I am better off avoiding polymorphism at the
> beginning, huh?  I should just be doing a simple mapping...
> --
> Posted viahttp://www.ruby-forum.com/.
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Correction to my previuos message: you can use "belongs_to" and
"references" as column types in scaffold (and migrations). They do
same thing: add belongs_to association to model.

On Jun 4, 9:05 am, Ugis Ozols
<ugis.ozo...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> I''ve written a short example about has_many, belongs_to
-http://gist.github.com/425026
>
> has_many, has_one, belongs_to deffinitions goes into model and not in
> scaffold. You can use "references" like this: script/generate
scaffold
> address company:references address:text
>
> but as I mentioned in this
discussionhttp://railsforum.com/viewtopic.php?id=39325
> (look for andain''s posts) I''m running into problems where
views are
> generated without appended _id. Maybe I''m just doing something
wrong
> or just not getting it right ...
>
> Anyway I hope i shed some light on your problem.
>
> On Jun 4, 2:18 am, Kevin Hastie
<li...-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org> wrote:
>
> > Kevin Hastie wrote:
>
> > I guess what I really want is something like this:
>
> > class Address< ActiveRecord::Base
> >   belongs_to :addressable, :polymorphic => true
> > end
>
> > class Business< ActiveRecord::Base
> >  has_one :address, :as => :addressable
> > end
>
> > class School < ActiveRecord::Base
> >  has_one :address, :as => :addressable
> > end
>
> > h) I don''t suppose there is a way to do that with the
scaffold.  Is
> > there a typical set of scaffold options that would map to this?
>
> > i) Lastly, I guess I am better off avoiding polymorphism at the
> > beginning, huh?  I should just be doing a simple mapping...
> > --
> > Posted viahttp://www.ruby-forum.com/.
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Kevin Hastie wrote:
> Kevin Hastie wrote:
> 
> I guess what I really want is something like this:
> 
> class Address< ActiveRecord::Base
>   belongs_to :addressable, :polymorphic => true
> end
> 
> class Business< ActiveRecord::Base
>  has_one :address, :as => :addressable
> end
> 
> class School < ActiveRecord::Base
>  has_one :address, :as => :addressable
> end
> 
> h) I don''t suppose there is a way to do that with the scaffold. 
Is
> there a typical set of scaffold options that would map to this?
> 
> i) Lastly, I guess I am better off avoiding polymorphism at the 
> beginning, huh?  I should just be doing a simple mapping...
What about the polymorphic example I gave?  It seems like this is the 
best practice approach, but I am finding it VERY hard to find examples 
that I can get to work, and I feel like I see lots of complaints that 
the feature is "broken" within Rails.

Is it only for has_many relationships or can it be used like I am trying 
with has_one relationships?  Is my example the correct way to go about 
it?  If so, what else needs to happen?

(and what about questions h and i?)

j) What seems much easier is to have the Business and School tables to 
each have an address_id, and be done with it.  That''s what I would have
done days ago were I programming a language without so many "handy" 
shortcuts.  But to do so, doesn''t it have to be

Address
has_one :business
has_one :school

Business
belongs_to :address

That doesn''t seem right..?
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i am interested in the answer to this as well.

please post if you find out.
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Kevin Hastie wrote:
[...]
> j) What seems much easier is to have the Business and School tables to 
> each have an address_id, and be done with it.
That''s correct.
>  That''s what I would have 
> done days ago were I programming a language without so many
"handy"
> shortcuts.  But to do so, doesn''t it have to be
> 
> Address
> has_one :business
> has_one :school
> 
> Business
> belongs_to :address
> 
> That doesn''t seem right..?
That''s only right if you want an address to treat associated businesses
and schools differently.  If you just want an address to have_one (or 
more likely many) associated generic entities, then you need 
polymorphism.

Best,
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Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org
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