Rails - Oct 2005 - join tables and position (acts_as_list)

I''m working on some schema for a new project that we''ll be
doing in
rails (our first rails project!).

A recurring structure we are seeing is the desire to define an  
ordering any way we wish, so ''acts_as_list'' comes to the
rescue.
But, the ''position'' column seems to need to belong in the join
table
to make sense.

For example, we have lots of widgets listed in a ''widgets''
table.  We
have attributes that the widgets can have, so we have a join table  
between ''attributes'' and ''widgets'' (many to
many).  Now, we want to
be able to order the widget attributes any way we wish /per widget/.   
That is, when you view a page which details the widget, it''s  
attributes are shown and are ordered in a particular way for that  
widget.

Make sense?  How would this work for my models in rails?

Sample schema (in PostgreSQL):

CREATE TABLE widgets (
id serial,
"position" int, -- for all widgets ordering
name text,
description text,
etc.
etc...);

CREATE TABLE attributes (
id serial,
"position" int, -- for all attributes ordering
name text,
description text,
etc.
etc...);

CREATE TABLE attributes_widgets (
"position" int, -- for attributes per given widget ordering
widget_id int references widgets (id),
attribute_id int references attributes (id),
etc.
etc...
);


Phil

Ouch, I may have answered my own question. It can''t be done right now:

http://dev.rubyonrails.com/ticket/2025

:''(

A possible workaround might be to use views and rules, but I think  
that would mean a lot of them (a view and model for each widget)  
which would be icky for when widgets are added or deleted.


Phil

On Oct 14, 2005, at 4:00 PM, Philip Edelbrock wrote:
>
> I''m working on some schema for a new project that we''ll
be doing in
> rails (our first rails project!).
>
> A recurring structure we are seeing is the desire to define an  
> ordering any way we wish, so ''acts_as_list'' comes to the
rescue.
> But, the ''position'' column seems to need to belong in the
join
> table to make sense.
>
> For example, we have lots of widgets listed in a
''widgets'' table.
> We have attributes that the widgets can have, so we have a join  
> table between ''attributes'' and
''widgets'' (many to many).  Now, we
> want to be able to order the widget attributes any way we wish /per  
> widget/.  That is, when you view a page which details the widget,  
> it''s attributes are shown and are ordered in a particular way for
> that widget.
>
> Make sense?  How would this work for my models in rails?
>
> Sample schema (in PostgreSQL):
>
> CREATE TABLE widgets (
> id serial,
> "position" int, -- for all widgets ordering
> name text,
> description text,
> etc.
> etc...);
>
> CREATE TABLE attributes (
> id serial,
> "position" int, -- for all attributes ordering
> name text,
> description text,
> etc.
> etc...);
>
> CREATE TABLE attributes_widgets (
> "position" int, -- for attributes per given widget ordering
> widget_id int references widgets (id),
> attribute_id int references attributes (id),
> etc.
> etc...
> );
>
>
> Phil
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>