Ruby/rails port of Cocoon/hibernate

Rails
21

Hi,
I have just come across an article which states that primary keys must
be
auto-increment and id(which I know can be overridden). So when I am
dealing,
in hibernate, with the following:

<?xml version="1.0" encoding="UTF-8"?>

which basically says that the primary id is ‘assigned’ and mapped to the
artist_id column of the artisttbl with a one to many relationship
against
the artistimagestbl, the artist_id being the Foreign key, how would this
be
reflect in ActiveRecord? The database schema alraeady exists, I just
want to
see how ruby/rails/activerecord would reflect this in actual code.

What actual rails/activerecord command would be needed to say 'go away
to
this dB and create all the required activrecord classes based on the dB
schema?

–
Regards

Andrew

22

Hi,
No worries with this one guys. I have a handle on this now.

I would still like to know how to ensure that a primary key can be
‘assigned’. The following code would associate an auto_increment key
correct?:

class Usertbl < ActiveRecord::Base
set_primary_key “user_id”
end

So how do I make the primary key assignable?

–
Regards

Andrew

23

Assignable meaning not auto_increment and you take care of the value
yourself? ActiveRecord doesn’t really like that. It basically requires
that
it take care of handling the primary key. I’m not sure if there’s a
plugin
to work around this, but you’ll probably have to jump into AR itself if
you
start getting crazy with the keys.

Unless of course someone knows a proper way of doing this.

Jason

24

Hi Jason,

Assignable meaning not auto_increment and you take care of the value

yourself?

Yes.

ActiveRecord doesn’t really like that. It basically requires that it
take

care of handling the primary key.

Hmmm…not so good! Let’s say you have an order object with
corresponding
order items FKey referenced by order_id. If the order table is auto
generating its own id and each order item is also doing the
same…nothing
will work, plus I can’t change the table structure as it is needed by
another system!!!

I’m not sure if there’s a plugin to work around this, but you’ll
probably

have to jump into AR itself if you start getting crazy with the keys.

AR? What’s that?

–
Regards

Andrew

Unless of course someone knows a proper way of doing this.

25

On Mar 1, 9:26 am, “Andrew M.” [email protected] wrote:

Hmmm…not so good! Let’s say you have an order object with corresponding
order items FKey referenced by order_id. If the order table is auto
generating its own id and each order item is also doing the same…nothing
will work

This is a very standard, basic model setup. It will work just fine in
Rails. Generate models for order and order item, then add to order.rb:

has_many :order_items

add to order_item.rb

belongs_to :order

and Rails will work as you describe. The curious thing is why you
don’t trust Hibernate to perform id management for you? Are you doing
something unusual?