> What do you mean by "without talking to the data-store directly"?
The phrase 'talking to the data-store directly' is from the online Datamapper documentation under the section titled 'Talking directly to your data-store': http://datamapper.org/docs/find.html > I can't immediately fathom what any ORM's behaviour should be In ActiveRecord I can create outer joins using sql fragments: Privilege.select("privileges.user_id, privileges.description, users.user_name ").joins('LEFT OUTER JOIN users ON privileges.user_id = users.id').where("privileges.description = 'delete rights' ") This would return to me an ActiveRecord object. On Dec 7, 3:40 pm, Jordan Ritter <[email protected]> wrote: > What type of concrete objects would you expect the ORM layer to return, if > such a method call existed? Outer joins tend to be used for getting mixed > tuples of data that don't correspond to concrete ORM types. I can't > immediately fathom what any ORM's behaviour should be.. > > What do you mean by "without talking to the data-store directly"? The only > way I see to do this is to pass the DM adapter the SQL directly, and process > the responses as abstract tuples of data (you'll get back an array). You > could hydrate objects yourself manually from there, but YMMV: with any kind > of outer join you can end up with nulls, and extra > check-fields-before-hydration logic would be crappy to deal with (and why > bother - this is DM's job to begin with). > > FWIW, you might consider using direct SQL to conduct your outer join(s) and > only retrieve primary keys, then use the ORM to hydrate the objects akin to > User.all(:id => [..]). > > cheers, > --jordan > > On Dec 7, 2011, at 1:07 PM, terminal_breaker wrote: > > > > > > > > > Is there a way to do left outer joins in Datamapper without having to > > resort to talking to the data-store directly. I've been searching the > > net and the Datamapper docu with not success on details how to do so. > > > For example: > > > SELECT p.user_id, p.description, u.user_name > > FROM privileges p > > LEFT OUTER JOIN users u ON (p.user_id = u.id) > > WHERE p.description = "delete rights" > > > And let's say that I have a User class and a Privilege class too. > > > -- > > You received this message because you are subscribed to the Google Groups > > "DataMapper" group. > > To post to this group, send email to [email protected]. > > To unsubscribe from this group, send email to > > [email protected]. > > For more options, visit this group > > athttp://groups.google.com/group/datamapper?hl=en. -- You received this message because you are subscribed to the Google Groups "DataMapper" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/datamapper?hl=en.
