Re: Check for certain changes in @PreUpdate listener class

Thanks Michael! This works excellently for attributes on the entity, but I've yet to find a good solution when dealing with FKs (when to-one relationships are modified).

I've opted to just don't update modificationDate when relationships are touched for now so… At least halfway there :).

Thanks,
- hugi



> On 13 Jul 2020, at 13:23, Michael Gentry <[email protected]> wrote:
> 
> Hi Hugi,
> 
> You might have to compare everything to be certain.  Here is something I've
> used in the past (for Cayenne 3.x) which might be helpful:
> 
> https://gist.github.com/mrg/4dce22b67175c27f4047#file-cayenneutils-java-L105
> 
> 
> On Mon, Jul 13, 2020 at 9:11 AM Hugi Thordarson <[email protected]> wrote:
> 
>> Hi all.
>> Almost all of my objects have attributes called creationDate() and
>> modificationDate(), these are populated in a listener attached to the
>> DataDomain:
>> 
>> https://gist.github.com/hugith/a40faae5529a1826d601515a9e8c5206
>> 
>> Relatively simple and has served me well for the past few years. One thing
>> has always irritated me though. This method of doing things means that if
>> the only change to an object is to a to-many relationship,
>> "modificationDate" will get updated (for example: User has a relationship
>> user<-->>invoices, the user creates an invoice which is then added to his
>> "invoices" relationship. modificationDate is then updated even if there was
>> no logical change to the user itself).
>> 
>> So, I'm wondering… Is there any good way in the listener to check what
>> attributes have changed, so I can skip the update to modificationDate if
>> the only changed properties are to-many relationships?
>> I know I could implement a CommitLogListener and use the ChangeMap from
>> there, but as you see I'm doing these updates before committing, making
>> these changes a part of the same commit (which I'd much prefer to keep that
>> way).
>> 
>> Cheers,
>> - hugi