On Jan 13, 12:51 pm, Philip Hallstrom <[email protected]> wrote: > Interesting. I don't think AR will ever get the right data types since it > has no idea what "sum_quantity" should translate to. In Rails 3, Postgresql > 9.x I have User and BlogPost. Users have many blog posts. Use also has an > 'old_accounts_id' which is an integer and we'll use for summing... I think > this matches your setup... > > ruby-1.8.7-p330 :023 > BlogPost.sum(:old_accounts_id, :joins => :user, :group > => 'blog_posts.id').first > > SQL (3.8ms) SELECT SUM(old_accounts_id) AS sum_old_accounts_id, > blog_posts.id AS blog_posts_id FROM "blog_posts" INNER JOIN "users" ON > "users"."id" = "blog_posts"."user_id" GROUP BY blog_posts.id > > => [5603, "0"] > > ruby-1.8.7-p330 :024 > User.sum(:old_accounts_id, :joins => :blog_posts, > :group => 'blog_posts.id').first > > SQL (5.0ms) SELECT SUM("users"."old_accounts_id") AS sum_old_accounts_id, > blog_posts.id AS blog_posts_id FROM "users" INNER JOIN "blog_posts" ON > "blog_posts"."user_id" = "users"."id" GROUP BY blog_posts.id > > => [5603, 0] > > Note that by switching the query around so I run the query on the model I'm > summing and join the other one I get back integers. > > The only difference that I can think of is that in the former AR knows about > 'BlogPost' and 'sum_old_accounts_id' and even with it's magic can't relate > the two. In the latter (i'm guessing, haven't checked the code) that it > knows 'User' and 'sum_old_accounts_id'. It knows that it called 'sum' to > turns it into 'old_accounts_id' which it knows is a field of User so type > casts it. > > Maybe. Would be interesting to dig into the source and see.... >
You've pretty much hit it on the head - digging into the 2.3.10 source (what I've got handy) shows the code calling column_for on the given name, which will *only* return a column object if it's a field on the model you called .sum on. That column is then used to cast the result to the correct type. [lines 241-312 in calculations.rb, 2.3.10 version] The SQlite3 issue is a red herring - there's a whole different typing mechanism in play there: http://www.sqlite.org/datatype3.html It might be a worthwhile patch to try looking up the column in the *right* table, but that's only going to be obvious when the name is qualified (:'users.old_account_id') instead of just :old_account_id (allowed by SQL, if it's not ambiguous). --Matt Jones -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" 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/rubyonrails-talk?hl=en.
