Rails - Apr 2005 - Overriding ActiveRecord::Base for fun and profit

Hi all,

    ror has been much fun the past few weeks.  I''m looking forward to
using it where I can in the future.

    AR is great, but now my application is at a level where I am ready
to think about optimizations.  The database is the first spot to start,
as it is the most hellish.

    How about this: if you dont send an argument to find_all, I''ll give
you back some join data.  If you only ask for a where clause, I''ll pass
that along and send you join data.

class Claim < ActiveRecord::Base
  #appripriate has_many and belongs_to entries....

  def Claim.find_all (*args)
    sql  = "SELECT claim.*, client.title as client_title, division.title
as division_title, project.title as project_title "
    sql << "FROM claim "
    sql << "JOIN client on (claim.client_id = client.id) "
    sql << "JOIN division on (claim.division_id = division.id) "
    sql << "JOIN project on (claim.project_id = project.id) "
    sql << "WHERE #{args[0]} " if args[0]
    sql << "ORDER BY claim.claimant_name ASC"

    return find_by_sql(sql) if args.nitems == args.length #if you sent
nothing
    return find_by_sql(sql) if args[0] #if you sent a conditional
    super *args #if we''re confused
  end

end

    So what are the central failing points of this? If I had a way to
remap claim.client_title to claim.client.title I would also be able to
use the same variable names across my application, and use speedy joins
in 90% of the cases.  Also as a thought is doing the reverse, making
claim.client.title show up as claim.client_title.  I''m happy with this
how it is now, I''m just trying to think of ways It can/will bit me in
the ass, and ways to make it more transparent as an optimization.

Thanks all,

-Matthew Beale

On 15/04/2005, at 11:04 AM, Matthew Beale wrote:
> Hi all,
> So what are the central failing points of this? If I had a way to
> remap claim.client_title to claim.client.title I would also be able to
> use the same variable names across my application, and use speedy joins
> in 90% of the cases.  Also as a thought is doing the reverse, making
> claim.client.title show up as claim.client_title.  I''m happy with
this
> how it is now, I''m just trying to think of ways It can/will bit me
in
> the ass, and ways to make it more transparent as an optimization.
I think what your trying to get at is not only supporting eager loading 
of associated objects, but eager loading of only certain properties of 
associated objects.

For example, instead of just:
Post.find(:all, :include => :categories)

you could say:
Post.find(:all, :include => { "categories" =>
["property"] } )

Not convinced its too useful...

- tim