aspose file tools
The moose likes Object Relational Mapping and the fly likes Handling in memory objects with autogenrated key Big Moose Saloon
  Search | Java FAQ | Recent Topics
Register / Login


JavaRanch » Java Forums » Databases » Object Relational Mapping
Reply Bookmark "Handling in memory objects with autogenrated key" Watch "Handling in memory objects with autogenrated key" New topic
Author

Handling in memory objects with autogenrated key

sameer sood
Ranch Hand

Joined: Dec 05, 2007
Posts: 30
Hi
i am facing a problem when working with Hibernate
It is like this
Say i have an object mapped class mappedClass which is in memory
The table to which it is mapped is having an auto generated key element
So the problem occurs here i have an ArrayList of objects in memory i apply them to the database
The in memory don't get auto generated keys from database
so how to make this happen as my page requires this objects to be reeddited
like save and continue editing thing???


Sameer Sood
SCJP 1.5 (93%), SCWCD 1.5 (95%)
Cameron Wallace McKenzie
author and cow tipper
Saloon Keeper

Joined: Aug 26, 2006
Posts: 4967

When you say 'in memory', do you mean stored as an instance variable in your program, or stored in the cache of the Hibernate Session. I'm guessing it's the former.

If these are persistent objects, why not use the Hibernate cache, and not duplicate the caching in your program. Just pull the properties out of Hibernate directly, rather than performing a double cache. You'll get the most up to date values, and you won't have problems finding the primary key!

-Cameron McKenzie


Author of Hibernate Made Easy, What is WebSphere???, JSF 2.0 Made Easy and the SCJA Certification Guides
sameer sood
Ranch Hand

Joined: Dec 05, 2007
Posts: 30
I did a workout of my own on this but i have no idea about hibernate cache
Cameron Wallace McKenzie
author and cow tipper
Saloon Keeper

Joined: Aug 26, 2006
Posts: 4967

Don't get too intimidated by the term 'cache.' It's just the objects that the Hibernate Session has 'touched' or used while a transaction is in the works, and as such, the Session has a copy of it. It maintains this copy in memory, and maintains any updates that happen to the object. Then, when the transaction commits, all the objects in the cache have their final state persisted to the database.

Here's a little tutorial on the topic of how Hibernate and the Hibernate Session works:

How Hibernate Works: From Transient Objects to the Hibernate Cache

Happy Hibernating!

-Cameron McKenzie
sameer sood
Ranch Hand

Joined: Dec 05, 2007
Posts: 30
Been Hibernating a lot seem to have got some hold if it
updating auto generated keys gave pains too
But finally i am able to do all that
thanks for the quick replies
 
I agree. Here's the link: http://zeroturnaround.com/jrebel - it saves me about five hours per week
 
subject: Handling in memory objects with autogenrated key
 
Similar Threads
Auto increment key in Hibernate
Persistence of related objects with same auto-generated key
hbm without primary key
hibernate hbm for this relation
Hibernate Mapping- composite id (pk+ foreign key)