I'd rather we don't introduce a potentially expensive comparison in the
superclass setters. A setter may be called many times before a commit, so the
assumption is that it is much cheaper to only do comparisons once during commit.
I guess you can generate special setters with a custom template. Or we may run
pre-commit logic from within 'hasChanges'...
Andrus
On Mar 11, 2011, at 10:22 PM, Michael Gentry wrote:
> I just did a quick test using:
>
> DataContext dataContext = DataContext.createDataContext();
>
> User user = dataContext.newObject(User.class);
>
> user.setFirstName("System");
> user.setLastName("Administrator");
> user.setUsername("admin");
>
> dataContext.commitChanges();
>
> user.setFirstName("System"); // This isn't a real change
>
> System.out.println(dataContext.hasChanges());
>
> dataContext.commitChanges();
>
> In a nutshell, create a user, commit it, set a value to the same
> value, then check hasChanges(). The output is:
>
>
> INFO: INSERT INTO Users (first_name, id, last_name, password,
> username) VALUES (?, ?, ?, ?, ?)
> INFO: [bind: 1->first_name:'System', 2->id:200,
> 3->last_name:'Administrator', 4->password:NULL, 5->username:'admin']
> true
>
> The "true" is that the dataContext has changes, even though the second
> commitChanges() doesn't do anything (there are no real changes).
> Should we modify CayenneDataObject's writeProperty() to check if the
> old value and new value are equal before calling propertyChanged()? I
> was also noticing Embeddables doing something similar.
>
> Thanks,
>
> mrg
>
