xpusostomos opened a new issue, #14378:
URL: https://github.com/apache/grails-core/issues/14378
Grails has a special field "lastUpdated", which auto-populates the update
date. You can make this field nullable: false, which makes sense... why should
an auto-updated field be nullable.
But what if I want to make my own auto-populated field? Like say, the user
who updated the record. It would seem that Grails @Listener service was
designed primarily to implement auto-updated fields. At least that's what the
documentation implies, I'm sure other uses might exist, but this its main
reason. So we could implement auto user update field like this:
```
class RecordUserAuditService {
def springSecurityService
@Listener([Account])
void onPreInsert(PreInsertEvent event) {
User user = springSecurityService.currentUser
event.entityAccess.setProperty('userCreated', user)
event.entityAccess.setProperty('userUpdated', user)
}
@Listener([Account])
void onPreUpdate(PreUpdateEvent event) {
User user = springSecurityService.currentUser
event.entityAccess.setProperty('userUpdated', user)
}
}
```
ok, so this will autopopulate the field...
but wait... this only gets called when the session is flushed, it doesn't
get called prior to validate, and so it is impossible to auto-populate a
nullable: false field. It is impossible to do what grails does for you with
lastUpdated. When you call save() on your object, it will call validate() and
fail... even though it would have later been correctly populated.
I think if this feature was designed properly, Grails could cease having
"lastUpdated" as special, and the user could do it themselves. Personally, I
hate "lastUpdated" as a name, I'd rather call it updateDate or something, but I
don't have a choice, because the @Listener service doesn't work well enough to
roll your own.
Another problem of @Listener is it forces you to list every single domain
class. Why shouldn't I be able to have a wildcard match, and be able to check
myself if my domain class has the field in question? If 95% of my domains have
"userUpdated", it would be no overhead to always call it for all classes.
I also note that the example in the documentation populates
Book.friendlyUrl.... it makes friendlyUrl nullable: true... but makes no
mention of how critical it is to its functioning that it be set to nullable:
true.
One might be tempted to make it NOT NULL in the database, and nullable: true
in grails, just to force it to work... I guess that's a workaround, BUT... if
you're using grails to auto-generate the schema, then that will fail during the
development cycle.
### Expected Behaviour
We need a Listener that gets called before validate. We need a listener that
is capable of implementing something like lastUpdated.
We need a listener that optionally gets called for all domain classes and
can check if the class has a paricular property.
### Actual Behaviour
Tell us what happens instead
### Environment Information
- **Grails Version:** 4.0.12
- **JDK Version:** 1.8
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