I can't quite wrap my brain around the following situation.
I have an invoice, which is a row in the table Orders.
There are multiple items on the invoice, which are rows in table Items that are
keyed to the order.
I want to figure out how much this order weighs.
Weights for items are stored in the table SKUs. Each item points back to a
particular SKU.
In Sequel, I started out by trying to do something like
Orders[2543].items.skus.sum(:weight)
but of course that doesn't work. Then I started fiddling with
Orders[2543].items_dataset . . .
but reading through the documentation on associations didn't give me any idea
where to go next. I suspect if I go back to the docs for datasets I might
figure it out. However, when I start to feel like I'm just writing a flippin'
SQL query, except I'm doing it in a foreign language, that's when I wonder if
I've missed something.
Sure, I can just shove all the model crap out of the way and reach right into
the database and make it tell me what I want to know:
DB['select sum(skus.weight) from orders join items on (orders.id =
order_id) join skus on (sku_id = skus.id) where orders.id = 2543'].first
But I really like models. I just haven't figured out how to reach through a
model's associations to the associations beyond that except by bypassing the
whole thing and using SQL.
class Order < Sequel::Model
one_to_many :items
end
class Item < Sequel::Model
many_to_one :order
many_to_one :sku
end
class Sku < Sequel::Model
one_to_many :items
end
Can anybody point me in the right direction for this?
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