I am working with a legacy database and had problems searching for an object. When user enters code say "250" to search for an object database might store this id in several ways: "0000250" or "250 ". It depends what other legacy application was used to enter the data. So I needed a way to find out if object already loaded in second level cache without hitting the database. I want to check if object with id "0000250" is in cache, if not then check id "250 " and only after that call load method. I created this function:




Is there an easier way to verify that without going into internals of hibernate and second level cache? Someone suggested to implement my own cache provider but then I would also need to implement my own dataaccess. I am looking for few line of code, not a whole project to do it.

Ilativ;

Perhaps you can create an additonal synthetic attribute in your mapping using a formula to trim the leading zeroes from the value. In this way, that lookup attribute will never have leading zeroes, even if the true, unmodified attribute does. I am not sure if your legacy database would support this, but for clarity, here's an example of what I mean in Oracle:



Now you lookup in the cache by the formatedNumber attribute.

//Nicholas

Seems to me that implementing a custom Type via the UserType interface is what you want to do. This way you can coerce the values to and from the database. It would always be with "correct" value in hibernate.

How I can look up in cache using non id attribute? I thought only calling load or get with id will try to access cache. I am not talking about query cache.

I want to coerce not to access database

that is exactly what it is meant for... take a look at the UserType interface, and you'll see that it provides you the hooks right before it sends to the database and right after it retrieves from DB, via the preparedstatement and resultset, respectively.

-JT

Thanks. I tried that approach but it did not worked as I wanted. When I run ordinate queries it works, but when I do session.load(id) the hooks do not get invoked for the id. For instance if I search by name then id "000000250" is converted inside my hook to "250". But when I use session.load(clazz, "000000250") the hook that deal with resultset was not invoked. Maybe someone in hibernate team can take a look at this bug. Maybe they did it on purpose so user will not corrupt primary key. But then why it works for all other queries. They should still allow developers to overwrite that behavoir.

why aren't you invoking the load with the coerced ID? meaning use "250"...instead of "00000250"? After all, I assume your UserType is converting the data read from the DB to 250 as it is loaded into hib layer...right? and when you save data (via hibernate), you'd convert the "000000250" to "250"..right? The idea is to standardize your representation in hibernate, even though the db may have different from...right? If this doesn't help to clear up..then post your UserType code, and we'll have a look.

-JT