Would repository(:default).adapter.query(%Q{SELECT ... GROUP BY feed})
do the same job for you? This way you get an array of Structs back, or
am I missing something here? (It's pretty late, so I might be...)
mayo
On Aug 28, 10:19 am, Daniel Parker <[EMAIL PROTECTED]> wrote:
> I would like to strongly suggest that we AT LEAST devise a way to get
> at manually instantiating objects from sql results easier. I have one
> app, for example, where I have to construct a pretty complex sql query
> just to get the right objects, but at that point I'm grabbing whole
> records anyway, so it'd just make sense to me to be able to easily
> instantiate them into objects. I had to jump through all sorts of
> hoops to make it (my find_by_sql method) work, and then the next
> version jump of datamapper broke it. My example:
>
> Message.find_by_sql("SELECT messages.* FROM messages INNER JOIN
> (SELECT MAX(id) AS id FROM messages WHERE created_by =
> '#{current_openid}' GROUP BY feed) AS ids ON messages.id = ids.id")
>
> This basically selects the last-created message from each feed, only
> referencing one table. It worked great, and I think is a good example
> of something I have no other way of doing. BUT I'd rather instantiate
> them into objects from the sql, and not have to do it entirely
> manually.
>
> Is there a possibility we can at least provide a "not-recommended-but-
> available" way of doing it, and let developers shoot themselves in the
> foot until they do it right, if they want to?
>
> ~Daniel
>
> On Jul 15, 5:23 pm, Science <[EMAIL PROTECTED]> wrote:
>
> > Sam Smoot <[EMAIL PROTECTED]> wrote:
> > > > > Right. That back-end needs a syntax however. Otherwise we're expecting
> > > > > everyone's syntax plugins to manipulate the Query#conditions AST
> > > > > directly. Which is fragile.
>
> > > > > Also, I've gotta say, I'm probably speaking from a position of CS
> > > > > ignorance, but I have a sneaking suspicion that Ruby 1.9's ordered-
> > > > > hashes is one of the less good design decisions the MRI team has made,
> > > > > forcing a memory/computation hit, when for most uses, it doesn't
> > > > > matter. So MRI will be paying a penalty there for a very long time to
> > > > > come.
>
> > > > > Either way, condition order is *very* important. So unless someone can
> > > > > suggest a syntax that works across VMs, and preserves order, I'm un-
> > > > > moved from Yehuda's syntax. Plugins encouraged sure.
>
> > > > > -Sam
>
> > Sam - I brought up some related stuff on another thread but thanks for
> > pointing me here.
>
> > My opinion is that data mapper needs to support complex queries to the
> > extent that it permits "distributed" query building. One of the issues
> > I have is that building raw SQL is not very object oriented (duh) and
> > so in my OO architecture where different query segments are
> > constructed by various arms and legs of the objects, holding together
> > all the SQL is fairly difficult. I solved this problem by creating a
> > custom SQL object but it would be great to see Data Mapper support
> > this kind of stuff natively. The syntax sugar, ParseTree and all that
> > are fine but the real issue is that I need to do stuff like:
>
> > * create a new clause called "foo" ("or'ed" to previous clause)
> > * add several conditions to it
> > * create a second new clause "bar"
> > * add some conditions to it
> > * go back to "foo" and add some more conditions in there
> > * add two order by statements
> > * set "distinct on (x,y,z)" to the front of the select list
> > * add two more order by statements
> > * specify several table join statements
>
> > Being able to add SQL to the query in some order other than what SQL
> > expects is really the big deal for me. It lets me design my
> > application the way it "wants" to be built, rather than the way SQL
> > would like the output.
>
> > I hope this input is useful! Definitely drop me a line if I can
> > clarify anything.
>
> > Steve
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