On Mar 10, 12:05 pm, John Firebaugh <[email protected]> wrote:
> On Wed, Mar 10, 2010 at 11:16 AM, Jeremy Evans <[email protected]>wrote:
>
> > On Mar 9, 11:36 pm, John Firebaugh <[email protected]> wrote:
> > > The fact that one_to_one associations are a thin layer on one_to_many,
> > > specifically the need for them to be named in the plural, is causing a
> > fair
> > > bit of accidental complexity in a custom plugin we have that does heavy
> > > reflection on associations.
>
> > > What would be necessary to be able to name one_to_one associations in the
> > > singular?
>
> > I'm not sure of all the changes that would be needed to make it work.
> > It's possible that the changes are extensive enough to require the
> > creation of a real one_to_one association.
>
> It was easy to get the specs to pass, but I'm not sure if I'm missing
> something. See the attached patch.
>
> > That being said, it would be helpful for you to explain what the
> > actual issues you are running into are. It's possible that we just
> > need to add something to the association reflection classes to
> > eliminate or at least reduce the complexity.
>
> We have a filter interface similar to iTunes smart playlists:
>
> http://www.apple.com/itunes/how-to/index.html#playlists-smartplaylists
>
> The filter criteria support many_to_one and one_to_one relationships using
> eager graphing. When serialized, criteria look something like this:
>
> [['book.title', :=, "Where the Wild Things Are"],
> ['book.author.first_name', :=, "Maurice"],
> ['book.first_page.text', :contains, "Max"]]
>
> Assume book -> pages is one-to-many, and book -> first page is one-to-one
> based on the constraint page.number = 1. The complexity arises because the
> accessor method is #first_page but the association name is :first_pages --
> when processing the criteria, we have to special case 'book.first_page.text'
> to handle that. If we used 'book.first_pages.text' instead, we would still
> need special cases, just in different places. We really need the accessor
> name and association name to be the same.
I'll say that I like the general idea of making one_to_one use a
singular, enough to break backwards compatibility. When we do this,
it would also be a good time to define a one_to_one method that uses
the :one_to_one option of one_to_many.
Your patch looks good. You should remove the singularize call, as
singularizing an already singular word can return a different word.
Have you had a chance to test eager loading with the patch?
class Book < Sequel::Model
one_to_many :first_page, :class=>:Page, :conditions=>{:page_number=>1},
:one_to_one=>true
end
Book.first.first_page
Book.filter(:id=>[1,2]).eager(:first_page)
Book.filter(:id=>[1,2]).eager_graph(:first_page)
I'm not sure if there are any eager loading specs that cover this
particular case, which weren't really necessary before as
the :one_to_one option just added a couple instance methods and didn't
modify eager loading behavior at all. I don't expect any breakage
from this patch, but it would be nice to test that area first.
Thanks for your help!
Jeremy
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