Re: saving a one-to-many

First off, thanks for bearing with me here - I do appreciate all help and
advice.

Ok, onward:


> On Saturday 10 March 2007 03:46:03 pm Fred Janon wrote:
<snip>
> > Set items = new HashSet()
> >
> > Then in the controller just creating and adding an OrderLine to items
> > will trigger the automatic save of both by Hibernate after the controller
> > action retuns
>

After toying with this, I discovered that it (seemingly) still doesn't quite
do what I'm after.

To summarize:

I'm looking for the most idiomatic and/or succinct/direct method of
saving/persisting a one-to-many domain class instance.

I have something called a ServiceOrder, which can contain many line items,
facilitated via an OrderLine. Each OrderLine associates one or more Products
with any particular ServiceOrder:

.../domain/ServiceOrder.groovy:

class ServiceOrder {

   static hasMany = [ items : OrderLine ]

   Set        items      = new HashSet()

   Contact    contact
   CreditCard creditCard

}

.../domain/OrderLine.groovy:

class OrderLine {

   static belongsTo = ServiceOrder

   Integer      quantity = 1

   ServiceOrder serviceOrder
   Product      product

}


Now, what would be the generally recommended way to create and save a
ServiceOrder, complete with one or more OrderLines?

My original attempt was:

def serviceOrder = new ServiceOrder(
   contact    : new Contact( params ),
   creditCard : new CreditCard( params )
)
serviceOrder.save()

serviceOrder.addOrderLine(
   new OrderLine(
      serviceOrder : serviceOrder,
      product      : Product.get( params.productId )
   )
)
serviceOrder.save()


... which works, but - I don't know - I just get the suspicion this approach
is somehow naive; is my hunch wrong? Or is there actually a "better" way?

I was then helped along with Fred's advice to declare items as a Set/HashSet
in my ServiceOrder domain class, which led me to the following attempt:

def serviceOrder = new ServiceOrder(
   contact    : new Contact( params ),
   creditCard : new CreditCard( params ),
   items      : new OrderLine( product : Product.get( params.productId ) )
)
serviceOrder.save()


... which is more along the lines of what I'm looking for, however there
appears to be an issue with this because doing so in this manner creates an
OrderLine with a null serviceOrder:

dev=# select * from order_line ;
 id | version | product_id | service_order_id | quantity
----+---------+------------+------------------+----------
 30 |       0 |         18 |                  |        1


It's this general sense of a chicken-and-egg situation, in addition to my
being quite new to grails/gorm/groovy, which is prompting me to seek advice
from the list. Obviously, if the first approach works, then it works - but
I'm interested in how someone more experienced might achieve the same results,
or how I should modify the second approach to work correctly.

Many thanks!


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