unsavedvalue
2009/7/18 [email protected] <[email protected]>
>
> I'm new to NHibernate and I'm trying to get my head around the use of
> composite-id. I can get everything to work except SaveAndUpdate. I'm
> using verison 2.2.
>
> Table DDL is (unfortunately this can not change)
>
> CREATE TABLE `argon`.`layer` (
> `LAYERID` bigint(20) unsigned NOT NULL,
> `CENTREID` bigint(20) unsigned NOT NULL,
> `SERVERID` bigint(20) unsigned NOT NULL,
> `DESCRIPTION` varchar(256) DEFAULT NULL,
> KEY `Index_Layer` (`LAYERID`,`CENTREID`)
> )
>
>
> My mapping file so far is
>
> <?xml version="1.0" encoding="utf-8" ?>
> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
> assembly="Argon.Admin"
> namespace="Argon.Admin">
> <class name="Layer">
>
> <composite-id>
> <key-property name="LayerId"/>
> <key-property name="CentreId"/>
> </composite-id>
>
> <property name="ServerId" />
> <property name="Description" />
>
> </class>
>
> <query name="Layer.get_by_layer">from Layer where LayerId=:layer</
> query>
>
> <query name="Layer.get_by_centre">from Layer where CentreId=:centre</
> query>
>
> <query name="Layer.get_by_layer_and_centre">from Layer where
> (LAYERID=:layer) and (CENTREID=:centre)</query>
>
> </hibernate-mapping>
>
> And my code so far is
>
> [Serializable]
> public class Layer
> {
> public virtual long LayerId { get; set; }
> public virtual long CentreId { get; set; }
> public virtual long EMSServerId { get; set; }
> public virtual string Description { get; set; }
>
> public override Equals(Object aObject) {
> ...code omitted for brevity
> }
>
> public override int GetHashCode()
> {
> return (int)((LayerId * 1000) + CentreId);
> }
>
>
> public static Layer Save(Layer aLayer)
> {
> // Just a convienience call - if record does not exist
> then null returned.
> Layer existing_layer = GetByLayerIDAndCentreID
> (aLayer.LayerId, aLayer.CentreId);
>
> using (ISession session = OpenSession())
> {
> if (existing_layer == null)
> {
> session.Save(aLayer);
> }
> else
> {
> session.Update(aLayer);
> }
>
> session.Flush();
>
> return aLayer;
> }
>
> }
>
> ... rest of code omitted for brevity
> }
>
> Now this works but to me the Save method seems unweildy as I'm able
> just to use a SaveOrUpdate for all my other classes that have a simple
> primary key. If I try SaveOrUpdate then NH just does an update, fine
> for when an update is needed but fails for a new record.
>
> Reading the docs suggests that I can create a separate class to
> implement the key and refer to it in the composite-id element in the
> mapping. But when I do that the LayerID and CentreID fields of the
> Layer class do not get used, so for a method that gets data this end
> up blank.
>
> I was wondering if someone could give a clear example of the best (or
> a better) way of doing this assuming the database can not change.
>
> >
>
--
Fabio Maulo
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