[DataMapper] Re: Modeling Multiple Many-to-Many Relationships With One Model In Common
I was able to figure that out eventually. Thanks for listing all the
options!
On Apr 12, 9:10 am, mltsy wrote:
> > Now if I could just figure out how to query on a many-to-many.
>
> Querying shouldn't be too hard - have you figured it out?
>
> You can use:
> @photo.albums
> @album.photos(:person => p)
> @person.photos(:album => a)
> Photos.all(:album => a, :person => p) (to get all photos from person p
> in album a)
> or even
> Albums.all('photos.person' => p) (to get all albums containing at
> least 1 photo from person p. This only works using the string syntax)
>
> -Joe
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[DataMapper] Re: Modeling Multiple Many-to-Many Relationships With One Model In Common
>
> Now if I could just figure out how to query on a many-to-many.
>
Querying shouldn't be too hard - have you figured it out?
You can use:
@photo.albums
@album.photos(:person => p)
@person.photos(:album => a)
Photos.all(:album => a, :person => p) (to get all photos from person p
in album a)
or even
Albums.all('photos.person' => p) (to get all albums containing at
least 1 photo from person p. This only works using the string syntax)
-Joe
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[DataMapper] Re: Modeling Multiple Many-to-Many Relationships With One Model In Common
For those who might find this useful, I altered my calculus slightly and went this route: Person has n, :photos Album has n, :photos, :through => Resource Photo belongs_to :person, :required => true has n, :albums, :through => Resource Now if I could just figure out how to query on a many-to-many. Thanks. On Mar 15, 1:12 am, Neil Chaudhuri wrote: > I have a fairly straightforward modeling task involving People, > Albums, and Photos. Here are the business rules: > > *One person can have many photos. > *One album can have many photos. > *One album can have photos of many people. > *An album can have multiple photos belonging to the same person, but > not necessarily all the photos belonging to that person. > *Given an album, I would like some way to aggregate sets of photos by > the person they belong to (where each set is a subset of all the > photos that person has). So for example, I would like to say that in > Album 10, Bobby has his photos 9, 17, and 41 and Sally has her photos > 47, 57, 93, 201, 203. Of course, Bobby and Sally both have a lot more > photos than that but just not in this album. > > I would think the tables would look like this: > > Person > id | name > > Album > id | name > > Photo > id | filename > > PersonAlbumPhoto > person_id | album_id | photo_id > > My questions are these: > > *Is this a reasonable model for the business rules as I described? I > am happy to hear of something more elegant or efficient. > *How should I model my Ruby classes for Person, Album, and Photo to > generate what I need? > > Thanks for the insight. -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To post to this group, send email to datamapper@googlegroups.com. To unsubscribe from this group, send email to datamapper+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
