[hibernate-issues] [Hibernate-JIRA] Commented: (ANN-472) @UniqueConstraint declaration is not friendly towards inheritance or reflection
[
http://opensource.atlassian.com/projects/hibernate/browse/ANN-472?page=co...
]
Ted Bergeron commented on ANN-472:
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I am still puzzled about your suggestion. Currently I do have the annotations in place,
and my hibernate generated DDL has the unique constraints set in Oracle. If I insert a
row that violates the unique constraint I'll get a SQLException.
I'd like to go one better and have my view layer inspect the field of the model bean
and on finding a single or composite unique constraint, dynamically generate the DWR code
to validate this case. Thus, a user enters the name field, and tabs to other fields. DWR
fires off an event that tells my app layers to select the one or combination of fields to
check if they exist in Oracle. That returns a boolean to the view which alerts the user
to the problem before submit.
I know this is only 99% effective due to the race condition, but the SQLException will
cover the other 1%.
If I try to use the validator for this case, I have to populate a whole bean because
getPotentialInvalidValues and getInvalidValues only accept one property otherwise (not
multiple for a composite constraint). Then I'd have to iterate over InvalidValue[]
just looking for the specific combination of fields. This is where I am confused by your
suggestion. Without generating a select, how does the validator check that the unique
constraint is not violated?
@UniqueConstraint declaration is not friendly towards inheritance or
reflection
-------------------------------------------------------------------------------
Key: ANN-472
URL: http://opensource.atlassian.com/projects/hibernate/browse/ANN-472
Project: Hibernate Annotations
Type: Improvement
Versions: 3.2.0.ga
Environment: Hibernate 3.2 GA
Reporter: Ted Bergeron
The current way to define a composite unique constraint is limiting.
@Table(name="tbl_sky",
uniqueConstraints = {@UniqueConstraint(columnNames={"month",
"day"})}
)
Suppose I have an abstract base class called A that gives me Id and Name, subclassed by
abstract class B that gives me Customer. Then I have many concrete classes that subclass
B. For all of these, I'd want the combination of Name and Customer to be unique. As
I do not use @Table with abstract base classes, I currently have to repeat:
uniqueConstraints = {@UniqueConstraint(columnNames={"name",
"customer_id"})} on all concrete classes.
If we had an alternate way to define these constraints at the property level (as XDoclet
did with hibernate 2), I could define this in the base classes and inherit the constraint
declaration.
The other need is that I would like to use reflection to scan the properties and apply
proper validations in the view layer. With @Column(unique = true) this is easy to do.
The view layer makes an AJAX call and all is well. For a composite constraint, it does
not work well currently.
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