rails:freeze:gems | freezzo.com

The other day I had to display the number of children items an object had so I decided to do the following:

# Controller
@customers = Customer.find(:all, :include=>[:receive_payments])
 
#View
<%= customer.receive_payments.count %>

While this worked for what I needed, it executed the following sql every iteration:

SELECT count(*) AS count_all FROM "receive_payments" WHERE ("receive_payments".customer_ref_list_id = E'850000-1071531366')

I thought this wasn’t right considering I used an association, however when you use count, it forces the use of count(*) on the database. This is where size comes in!!!!

<%= customer.receive_payments.size %>

Now we get the same results without the extra database counts!

I’m sure you all know how to use the :conditions attribute when using ActiveRecord:

User.find(:all, :conditions=>['active = ?', true])

And you may even use associations this way:

User.find(:all, :include=>[:photos], :conditions=>['photos.removed = ? and users.active = ?', false, true])

But did you know that you can do this easier through hashes?

User.find(:all, :conditions=>{:active=>true})
User.find(:all, :include=>[:photos], :conditions=>{'photos.removed'=>false, 'users.active'=>true})

Nothing special there, but I thought it was pretty cool. One thing you have to remember when using associations, is to include that model.