Re: EO: Should I create primary keys?
Re: EO: Should I create primary keys?
- Subject: Re: EO: Should I create primary keys?
- From: Denis Stanton <email@hidden>
- Date: Tue, 29 Jul 2003 15:42:32 +1200
On Tuesday, July 29, 2003, at 01:38 PM, Goodbye Bill wrote:
> Previously, I was creating the "Link" object and then setting a couple
> of
> foreign keys manually. Now, the keys of the "Link" object are not
> exposed.
> I'm assuming I'm supposed to add one object directly to the other and
> let EO
> handle the association. But how?
After you set up the relationships in EOM you would gave generated Java
classes which would include method for creating the links.
Here's a tiny code sample. I have a Type table and a Vehicle table
with a one-to-many relationship. i.e, many vehicles for each type.
I create a new vehicle like this:
public Vehicle createVehicleForType(Type type){
Session session = (Session)session();
Vehicle newVehicle = new Vehicle();
session.defaultEditingContext().insertObject(newVehicle); //
otherwise it won't get saved to database
newVehicle.setVehicleName( "E type Jaguar" );
< set other Vehicle instance variables >
type.addToVehicles(newVehicle); // adds the vehicle to the
array of vehicles for this type
newVehicle.setType(type); // sets the foreign key in my Vehicle
instance to point to my Type instance.
session.saveChanges();
}
This is assuming that Vehicle has a relationship named "type", which
causes EOM to generate a method
public void setType(Type value) {
takeStoredValueForKey(value, "type");
}
and Type has a method
public void addToVehicles(Vehicle object) {
includeObjectIntoPropertyWithKey(object, "vehicles");
}
Denis Stanton
email@hidden
Home: (09) 533 0391
mobile: 021 1433622
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