Need help optimizing some Rails 2.3 ActiveRecord code

(Hi Dr. Nick!)

I'm trying to tighten things up for our app admin, and in a few places we have some pretty skeezy code.

For example, we have Markets, which contain Deals. In several p开发者_如何学编程laces, we do something like this:

@markets = Market.find(:all, :select => ['name, id'])
@deals = Deal.find(:all, :select => ['subject, discount_price, start_time, end_time'], :conditions => ['start_time >= ? AND end_time <= ?', date1 date2])

Then in the corresponding view, we do something like this:

@markets.each do |m|
  =m.name
end

@deals.sort!{ |a,b| a.market.name <=> b.market.name }
@deals.each do |d|
  =d.subject
  =d.market.name
end

This runs a stupid amount of queries: one to get the market names and ids, then another to get all the deal info, and then for each deal (of which there are thousands), we run yet another query to retrieve the market name, which we already have!

Tell me there is a way to get everything I need with just one query, since it's all related anyway, or at least to clean this up so it's not such a nightmare.

Thanks

You can write like this way ..

@deals_with_market_name = Deal.find(:all, :include => :market, 
:select => ['subject, discount_price, start_time, end_time,market.name as market_name'], 
:conditions => ['start_time >= ? AND end_time <= ?', date1 date2], 
:order => "market.name")

And in view ...

@deals.each do |a|
  =a.subject
  =a.market_name
end

Try it...

If you use :include => :market when searching the deals you won't run a query to retrieve the market name for each deal. It'll be eager loaded.

@deals = Deal.find(:all, :include => :market)

Hope it helps.