Hi again, it's worth noting that if you have the ability to change up your
db, you might want to look at using a surrogate key with an idbag, they're
more efficient, and have fewer gotchas than composite ids.
I noticed a bit more upon a second look: your bags in Shipping and Days
don't have inverse="true" .. but you probably want to have that-the default
behavior is inverse=false, and that means your shipping_method and day
columns in your primary key needs to be nullable, as the implication is that
DeliveryDay doesn't require shipping_method or days to be meaningful. in the
inverse="false" scenario you're running under that's how things are. As your
PK is made up of these two things, they are most definitely NOT optional,
ever. (If either should be optional, take them off your PK)
inverse=false works like this: NH will insert child object w/ parent id of
null, insert parent object, update child object with relationship. in the
case of deleting the child from the bag, you're talking the reverse, which
in thise case removes part of your primary key before your delete. note that
with inverse=true you're going to need to explicitly manage this
relationship on the DeliveryDay object end (ie your DeliveryDay.Day and
DeliveryDay.ShippingMethod. you can coordinate both directions by having an
add method (this is often on the class with the bag end) like this method in
ShippingMethod:
AddDeliveryDay(DeliveryDay d) {
d.ShippingMethod = this;
_deliveryDays.Add(d);
}
Hopefully that gets you closer, good luck!
On Sun, Oct 11, 2009 at 4:00 PM, mathmax <[email protected]>wrote:
>
> Thank you for your answer.
> I've added this property in the class and the mapping file and its
> corresponding field in the table, but I still get this error when
> deleting an item:
> could not delete collection rows:
> [DeliveryDays.Shipping.Days#france_by_tnt_express][SQL: UPDATE
> delivery_days SET shipping_method = null WHERE shipping_method = ?p0
> AND shipping_method = ?p1 AND Day = ?p2]"
> Should I use unsaved-value="any" ?Should I use cascade="all" ?
> I'm saving using session.Flush() (not SaveOrUpdate) because I want to
> save all my entities.
> This is very strange because the SQL sent is an UPDATE and not a
> DELETE...
> Am I doing something wrong ?
>
> Best regards,
>
> mathmax
>
> On 11 oct, 17:55, Anne Epstein <[email protected]> wrote:
> > Composite keys are finicky. One key annoyance with them is that unless
> you
> > givroperly.e them a little help, composite-key entities can't properly
> use
> > SaveOrUpdate, and can't be used with cascading properly.
> >
> > Two fixes. you can implement an IInterceptor, or you can add a <version>
> > property. I haven't done the first, but I can say from experience the
> > second is simple enough. Just a few things you need to do:
> >
> > 1) add a property to your class-just like any of your other properties in
> > your class... unless you do choose to use access="field..." in this case,
> > let's name your property LastModifiedOn. this new field is for
> NHibernate,
> > not for you, so you can look, but don't mess with it yourself. (you may
> > want to use access="field...." option so you man map directly to the
> private
> > field and you don't have to expose this outside your class-you'll need to
> go
> > to the NH docs and pick your naming strategy)-
> >
> > 2) add property to your mapping:
> > <version name="LastModifiedOn" type="timestamp" column="LastModifiedOn"
> > />
> >
> > 3) Don't forget to add the new field to the table! Note that if you add a
> > version column to an existing table, you're going to have to prepopulate
> the
> > existing rows for your your new column with an initial datetime or you'll
> > get errors-any date at all, so long as it's in the past. 1/1/2009
> 12:00:00
> > is as good a value as any....
> >
> > On Sun, Oct 11, 2009 at 1:45 AM, mathmax <[email protected]
> >wrote:
> >
> >
> >
> > > Hello,
> >
> > > I try to delete an item of a collection inside a transaction. When I
> > > flush the session I get this error because the class of the child
> > > items is mapped with a composite Id.
> >
> > > the mapping file look like this:
> >
> > > <class name="Shipping" table="shipping_methods" lazy="false">
> > > <id name="Id" column="id">
> > > <generator class="assigned" />
> > > </id>
> > > ...
> > > <bag name="Days" table="delivery_days" lazy="false" cascade="all-
> > > delete-orphan">
> > > <key column="shipping_method"/>
> > > <one-to-many class="DeliveryDay" />
> > > </bag>
> >
> > > </class>
> >
> > > <class name="DeliveryDay" table="delivery_days" lazy="false">
> > > <!--http://journalofasoftwaredev.wordpress.com/2008/04/19/
> > > nhibernate-exception-unexpected-row-count-0-expected-1/--<
> http://journalofasoftwaredev.wordpress.com/2008/04/19/%0Anhibernate-e...>
> >
> > > <composite-id unsaved-value="any">
> > > <key-property name="ShippingMethod" column="shipping_method" />
> > > <key-property name="Day" />
> > > </composite-id>
> > > ...
> > > </class>
> >
> > > I try with and without unsaved-value="any" on the composite-id tag
> > > cascade="all-delete-orphan", cascade="all" and no cascade attribute on
> > > the bag tag.
> > > But I always get an error.
> > > Depending on the cascade and unsaved-value attribute I get different
> > > error messages.
> > > With this mapping file I get this error : {"Unexpected row count: 0;
> > > expected: 1"}
> > > and it seems that the SQL sent to the database is an UPDATE statement
> > > instead of a DELETE statement... very strange.
> > > I also get sometimes this error when I try to add more than on item to
> > > the collection : {"a different object with the same identifier value
> > > was already associated with the session: DeliveryDays.DeliveryDay, of
> > > entity: DeliveryDays.DeliveryDay"}
> >
> > > Does anyone know what I am doing wrong with composite-key ?
> >
> > > regards,
> >
> > > mathmax
> >
>
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