Forum: Ruby on Rails Keep the Queries Down or "Referencing eagerly loaded models"

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Jodi S. (Guest)
on 2006-01-06 00:25
Before I start, I've read the ActiveRecord docs on eager loading, but
for the life of me, I can't seem to get it working.

What I mean by this, is that the eager query looks good (I can paste the
sql dump, but it looks good to me - and runs well independantly), but it
seems that I'm referencing the eagerly loaded data in a way that
activerecord doesn't understand (my assumption) - thus I'm getting a
tonne of extra queries.

[first, the domain:
WorkOrders has_many: WorkOrderItems
WorkOrderItems belongs_to :WorkOrder
WorkOrderItems belongs_to :ProductsAndServices

secondly, the controller looks like:
    @work_order = WorkOrder.find(params[:id])
    @work_order_items = @work_order.WorkOrderItems.find(:all, :include
=> [:WorkOrder, :ProductsAndServices ] )

(you'll note that I'm eagerly loading the work_order from the
work_order_item - that's because the WorkOrderItem model references its
work_order for some processing - see "pst" below)

And in the view, I reference as such:

@work_order_items.each {|item| <<
Hash["Part #", item.ProductsAndServices.part_number,"Description",
item.description, "Quantity",item.quantity, "Price",
number_to_currency(item.price), "Extended",

The above generates @work_order_items.count queries to the
ProductsAndServices table. Why is that? Do I reference the eagerly
loaded data incorrectly?

With the same symptom, further down in the same view I make a call to a
WorkOrderItems method "pst" - this method references both eagerly
referenced models - WorkOrders and ProductsAndServices using the syntax:

#calculate the line item pst
def pst
 if (self.WorkOrder.charge_pst? and
       sub_total * 0.07

Again, I see that database queries are made to retrieve both WorkOrder
and ProductsAndServices.

Probably the same problem on my part. Any ideas ninjas?

Thanx for any help.

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