Hibernate - Multiplatform handling of exception/errors

You could enable internal logging, which AFAIK can be configured to use log4j. This may give you even better info than simply db debug output

My problem is not particuarly about logging.... is about knowing what happened exactly when I operate in the database.

For instance:

An user tries to create a new Customer
Web layer calls Business Service
Business Service calls DAO
DAO implementation uses hibernate to insert into a database
Insert fails, because a duplicated UK constraint
Insert fails, for a invalid FK
etc.

All of these get wrapped into a ConstraintViolationExcepton for hibernate. There's no way to know exactly what kind of error I had but diving into the database specific error.
Only thing I could find is SQLCode which might be multiplatform, but I coudn't find a clear list / explanation of SQLCodes

>>is about knowing what happened exactly when I operate in the database.

Yes but enabling internal logging may tell you this

Hi,

You should not depend on sql error codes, because every database and every jdbc driver can have it's own codes.

Instead your application architecture should provide you way to know what happend. For example you should have method createNewCustomer(). Then you can catch Exception inside that method and display it or dispatch it to some higher level.

If you are dispatching the Exception, you are probably catching it in centrialized way (you are catching Exceptions on top level of your architecture) you need some way to recognize the type of Exception in order to know what message to display to user or logg it. One way is to introduce your own exceptions by extending Exception and then throwing it from your data acces layer - createNewCustomer method for example.

Then you could recognize the type of exception by calling instanceof operator.

if(exception instanceof CreateCustomerException)
   showMessage("error creating customer");

Another way is to have just one custom Exception which you will throw every time data acces exception occures. In that case you could have property "type" as instacne variable of your exception which will be used for recoognizig the type of the error.

You can have static final fields to map all possible exception types inside your Exception

class MyDAOException extends Exception
{
int errorType=0;

public static final int CREATECUSTOMERERROR =1;
}

theb ont top level you cah distinct error types lik this

MyDAOException ex;

if(ex.type==MyDAOException.CREATECUSTOMERERROR)
    showMessage("error creating customer");

CEHJ: Enabling internal logging might allow me to see there was an error and the DB specific code, but helps in no way to create a program that can diferenciate between a UK, PK or FK constraint violation without diving into DB specific issues.

Beegor:

>
>if(ex.type==MyDAOException.CREATECUSTOMERERROR)
>    showMessage("error creating customer");

Great explanation of exception handling from the java side, but my question was different. A "error creating customer" helps in no way to the user. I want to show him something  along the lines of "duplicated record" or "invalid value of Country for Customer" or "Cannot delete the customer that has pending payments" or "Check failed" or whatever. I needed a platform independent way of figuring that out using hibernate, as the constraints are already on the database (db independently).
Thanks for the comment about SQLCodes not working, it seems like , there's no way to figure it DB independently.
I wanted to avoid having to code db-specific functionality, but seems like I'll have no choice.

Yup, I figured it out...I ended up creating a view on the DB schema (which I will have to develop for each different DB engine) that extracts constraint info from the data dictionary...That way I can extract info (type, columns, table, etc) and from the java code its still DB independent.

Still, I find a bit odd that hibernate handles a lot of the operations in a tech independent way, but it really doesn't do much about the errors.

Thanks, you get credit.

>> database will not give you such specific explaination...

(which is why wrt to Hibernate i suggested enabling its own logging)

My advise is that you handle checks and data validation in your business and presentation layer. Persistance layer is last place and if there is error while you are updating or inserting something, that means that you didn't check enough.
If you think about it, message like this: "Cannot delete the customer that has pending payments" shold be result of checking for pending payments before you really try to delete it.


Thanx for credit!

Np on the credits.

About checking for pending payments: I dont want to do a select-before-insert, or select-before-delete, it has a lot of performance penalities. And, the point of having a relational database is that it can manage referencial integrity on itself, I'm not intending to recode the database in the business layer and use the relational database as a flat file :)

Cehj:
Enabling logging will do no good except for debugging, there's nothing I can do about checking a constrain in the logs unless I start to parse the debug log in runtime (EWWW!). It might help for diagnosing a problem, but really doesn't help at all on the constraint checking of the data.