Re: [Openinteract-help] has_many relationships?

[Ray Z. <rz...@co...>]

On Feb 15, 2004, at 8:45 PM, Vsevolod (Simon) Ilyushchenko wrote:
> I was wondering if it's possible to implement in SPOPS "has_many" 
> relationship (in addition to "has_a" and "links_to"). Obviously, it 
> can be done through "links_to", but at the cost of an additional 
> database table which makes things more cumbersome. For things like a 
> bug database, where one software project references several bugs, but 
> no bugs belong to more than one software project, "links_to" is an 
> overkill. If the id of the owner is stored in a field of the owned 
> object, the implementation can be similar to the already existing code 
> for the other relationships.

When you talk about a "has-many" relationship, I think you are just 
looking at the other end of a has-a relationship, right? To use your 
example, a bug has-a project that it belongs to. If I interpret 
correctly what it is that you want, you're looking for the ability to 
define a relationship that would automatically generate methods in your 
"software project" object to fetch the corresponding list of bugs, for 
example.

If so, I invested some effort a few years ago in defining a generalized 
relationship configuration syntax which handles this case (as well as 
the has-a and links-to). You can find my proposal in the 
openinteract-dev archives. The first one [1], posted on 7/3/01 is quite 
long and spells things out in pretty much detail. The second [2] was 
posted in Jan 2002 and includes some additions and updates to the 
proposed design.

At the time, Chris seemed pretty interested in eventually having some 
variation of this design included in SPOPS. I've implemented only small 
pieces of it for my own use and I suspect it just that on Chris's end 
it just came down to a shortage of tuits. Assuming I've interpreted 
correctly what you want, I would encourage you to have a look at what I 
proposed. It would be really wonderful if it addresses what you need 
and you actually have some time to implement it and get it incorporated 
officially into SPOPS.

[1] http://www.geocrawler.com/archives/3/8393/2001/7/0/6095774/
[2] http://www.geocrawler.com/archives/3/8393/2002/1/0/7464826/


Ray Zimmerman
Director, Laboratory for Experimental Economics and Decision Research
428-B Phillips Hall, Cornell University, Ithaca, NY 14853
phone:  (607) 255-9645       fax: (815) 377-3932