class ContainerCharge < ShipmentCharge
belongs_to :container
end
class Container < ActiveRecord::Base
has_many :container_charges
end
class HandlingContainerCharge < ContainerCharge
end
class ShippingContainerCharge < ContainerCharge
end
Controller
#Please assume here that this container has many Handling and Shipping
charges
container.container_charges # <- doesn’t return the handling and
shipping charges, only instances of the the super class
ContainerCharge
I would like the association to return all the container charges which
should be the right thing to do…
Anyone knows how to do this?
is going to add a where clause restricting the results to those where
the type is “ContainerCharge”.
STI is a bit funny in development mode - if the class isn’t loaded,
rails doesn’t know that it exists and so doesn’t know to include that
particular type in the where condition on type. I’ve got STI mixed
with associations in a few places and (as long as it knows that the
subclasses exist) a has_many like that does pull in subclasses. I
normally end up using require_dependency on the subclasses at the
bottom of the file defining the parent class
Hi Rick,
Of course I should have looked at the SQL query… and indeed, you are
perfectly right, Rails adds a WHERE clause on type… and it has to to
filter out the classes that are NOT involved:
SELECT count(*) AS count_all FROM “charges” WHERE
(“charges”.container_id = 1) AND ( (“charges”.“type” =
‘ContainerCharge’ ) )
Your idea is almost there, but Rails insists with the last AND clause
on the type… any idea on how to get ride of it?:
SELECT count(*) AS count_all FROM “charges” WHERE
(“charges”.container_id = 1 AND (“charges”.“type” IN
(‘ContainerCharge’,‘HandlingContainerCharge’,‘ShippingContainerCharge’)))
AND ( (“charges”.“type” = ‘ContainerCharge’ ) )
Thanks guys for your time. REALLY appreciated!
Regards,
Gam.
PS: I just realized that I didn’t specify that I’m using a STI… but
you figured it out…
Hi Rick,
Of course I should have looked at the SQL query… and indeed, you are
perfectly right, Rails adds a WHERE clause on type… and it has to to
filter out the classes that are NOT involved:
SELECT count(*) AS count_all FROM “charges” WHERE
(“charges”.container_id = 1) AND ( (“charges”.“type” =
‘ContainerCharge’ ) )
It should just be a case of ensuring all the subclasses of
container_charge are loaded
I have added:
has_many :container_charges,
:class_name => ‘Charge’,
:conditions => {:type => %w(ContainerCharge
HandlingContainerCharge ShippingContainerCharge)}
With this, Rails remove the problematic ##AND ( (“charges”.“type” = >
‘ContainerCharge’ ) ) ##. This seems like a big workaround not so
pretty but it works in the console. Now the field_for method doesn’t
see the charges in a form_for and I don’t know why… I’m almost
there!