Not 100% sure why, but heres two possibilities:
(1) Does Feed implement equals() and hashode() correctly?
I actually forget if that affects the behaviour of a bag.
(2) Did you change an Item after saving the Subscription?
For a bag that would cause a delete then insert, instead of
an update (a list or map or array would cause an update).
Note also that <bag>s cannot add and remove elements
individually (this makes perfect sense when you consider
the semantics of a bag). So you could also try changing to
a Set. ( Then you definiately need a proper implementation
of equals() and hashCode() ).
What exactly was the code that caused the four SQL
statements?
"Viktor Szathmary"
<[EMAIL PROTECTED]> To: "Viktor Szathmary"
<[EMAIL PROTECTED]>,
Sent by: [EMAIL PROTECTED]
[EMAIL PROTECTED] cc:
eforge.net Subject: Re:
[Hibernate] ... and how about bidirectional for a
component? :)
29/01/03 04:57 PM
On Wed, 29 Jan 2003 00:34:01 -0500, "Viktor Szathmary"
<[EMAIL PROTECTED]> said:
> On Wed, 29 Jan 2003 00:06:38 -0500, "Viktor Szathmary"
> <[EMAIL PROTECTED]> said:
> > hi,
> >
> > to annoy people with more trivial questions: is it possible to have a
> > bidirectional one-to-many relationship between a component and a
> > firstclass object? i'm getting a MappingException: "An association
refers
> > to an unmapped class" (which is not entirely true, since it is in fact
> > mapped as a component of another class).
>
> i also considered mapping this as a nested component list inside the
> component, but for some reason i'm still getting MappingException: "No
> persister for: net.sf.flock.hibernate.Feed".
bah, i am indeed senile. believe me, this hurts me as much as it does
you... :) i left an old one-to-one reference in the mapping. that
explains the second MappingException ("No persiter..."). So, here's a
mapping that seems to work:
<hibernate-mapping>
<class name="net.sf.flock.hibernate.Subscription" table
="subscription">
<id name="id" unsaved-value="null" length="32">
<generator class="vm.hex"/>
</id>
<component name="feed" class
="net.sf.flock.hibernate.Feed">
<parent name="subscription" class
="net.sf.flock.hibernate.Subscription"/>
<bag role="items" cascade="all">
<key name="id" type="string">
<generator class
="vm.hex"/>
</key>
<composite-element class
="net.sf.flock.hibernate.Item">
<parent name="origin"
class="net.sf.flock.hibernate.Feed" column="feed_id"/>
</composite-element>
</bag>
</component>
</class>
</hibernate-mapping>
however, apparently this is less efficient than a regular one-to-many
was: even upon the first save(..) it generates:
INSERT INTO Subscription ...
INSERT INTO Item ...
DELETE FROM Item ...
INSERT INTO Item ...
so, there's an extra delete & insert... what could be the reason?
thx,
viktor
ps. i promise in the future i'll spend more time thinking than posting..
:)
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