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Hibernate version: 3.0.5

How to handle HibernateException's correctly? For ex. I wanna show to user message "Object already exists" when he save Object to database, but all I have - HibernateException and I can't determine the reason.
Is that unique key violation or some column's constraint violation. How to determine that?

For example: I have a business method

// alsow throws unchecked SystemException which mean some database failure or external systems failure.
createUserAccount(UserAccount a) throws UserExistsException, ValidationException {
session.save(a) // HibernateException can be thrown in case of Account already exisit in database or Account name length < 1 char. Alsow in all cases HibernateException throws.
}

But I wanna throw specified exception for specifid case. How I should make it?

In your method createUserAccount you could manually check (with a query), if the user already exists in the database. If he does, you can throw your own exception.

Something like this:


Best regards
Sven

First. Ok. I am doing that now. But I should execute queries for each unique column (Yes it's possible to make using OR statement in HQL, I wanna to provide message which column not unique). Is it normal way?

Second. What about length constraints in relation model? How to handle them? I see only one way - validate data on client side and any relations errors consider as UNRESOLVABLE RuntimeExceptions. It this good?

1.
Are there so many unique columns for your class?

This way of querying might also be helpful:
http://www.hibernate.org/hib_docs/v3/re ... a-examples


2.
Validating data on the client side is a good idea.

I don't know the type of your application. If it's a web application based on Struts, you could easily implements validation using Jakarta Commons Validator (http://jakarta.apache.org/commons/validator/) in your beans.

You can also implement a so-called check constraint on database level. But this requires your database to support this type of constraint (e.g. Oracle).

Keep in mind that AFAIK there won't be a database error, if you try to insert a 100 character String into a 10 character database column - it will just be truncated.

You can also have a look at the Hibernate Validator (http://www.hibernate.org/hib_docs/annot ... #validator), but I don't know which version of Hibernate you're using. (It's a new feature in combination with Hibernate Annotations.)

Best regards
Sven