unidirectional one-to-one non-cascade delete

[adeelmahmood]

I have a simple 1-1 unidirectional relationship ..
class BulkEmail {
...
Template template
}
class Template {
...
}
so a single template can be used by a bunch of BulkEmails .. problem is when I try to delete the template which is being used by multiple bulkemails i am getting this error

2010-08-30 22:41:11,812 [http-8080-1] ERROR util.JDBCExceptionReporter - Integrity constraint violation FKDE7C6A2F88075EF9 table: BULK_EMAIL in statement [delete from template where id=? and version=?]
2010-08-30 22:41:11,812 [http-8080-1] ERROR events.PatchedDefaultFlushEventListener - Could not synchronize database state with session
org.hibernate.exception.ConstraintViolationExcepti on: could not delete: [beam.Template#1]

It makes sense why grails isnt able to do it .. it cant delete the template because its still being references by the BulkEmail objects .. I tried changing my code to something like this

BulkEmail.findAllByTemplate(templateInstance).each {
it.template.delete()
}
templateInstance.delete(flush: true)

this also doesnt works .. how can I delete a template while removing its referencing from all objects using it

Thanks
Adeel

[pledbrook]

Do you want the BulkEmails to remain after you have deleted the Template? I'm not sure it's particularly common, but you can do it by adding a nullable: true constraint to BulkEmail:

class BulkEmail {
    Template template

    static constraints = {
        template nullable: true
    }
}

Before you delete the template, you have to nullify all references to it:

def template = Template.get(templateId)
BulkEmail.findAllByTemplate(template).each { it.template = null }
template.delete()

You could also add a hasMany in Template and use the removeFrom() method instead. It's up to you.