I have a RoR app, and I want to display the join of several tables with
tens of thousands of rows (easy in Rails), and then be able to sort on
arbitrary columns when the user clicks on those columns, e.g.:
TableA.col1 TableA.col2 TableB.col1 TableB.col2
If it matters, TableA has a many-to-many relationship with TableB (and
so is mediated by a table named tablea_tableb), and TableB and TableC
have a many-to-one relationship.
So: big cross product join, lots of columns from lots of different
tables, and I want to be able to sort on arbitrary columns.
Now, rails has got totally painless facilities for getting an object
from an arbitrary table and then doing invisible joins to march along
these relationships from TableA to TableB, etc., but I don’t see what
I’m supposed to do if I want to impose a big arbitrary sort order on the
big table, i.e., if I want the user to be able to click on any arbitrary
column to sort on that column on the big huge table of everything.
I mean, obviously I could load the whole thing in memory and sort it
that way, but what if I don’t want to do that, because there’s a lot of
data? In the pre-RoR days, I’d just make an arbitrarily-evil SQL call,
creating the big join and sorting it as desired, all in one SQL call.
But what’s the RoR way? How do I display all the data I want, in the
order I want, without abandoning my Model objects, and without loading
the whole mess into memory?