Hibernate sequence exposed as property

[Richard Everhart]

In the application that I currently work on generators (of type sequence) are used to create the IDs for all of our objects, so I somewhat understand how this works.

What I need for a feature I'm adding is a integer value that is incremented during a particular point of execution in the program. I was thinking that a sequence would be perfect for this. Has anyone ever done this before? I can't seem to figure out how to expose (read and set) the sequence value.

Rich

[Mark Spritzler]

Well you can make your mapping to the attribute be a "formula" attribute which can be "SELECT mySequence.nextVal FROM Dual" in Oracle for example.

Mark

[Richard Everhart]

Thanks Mark.

Now my problem is creating the Hibernate configuration file. I've created the file but my sequence has no id column, which means that I can't provide an ID element withing my class element. Without the id element an XML parsing exception occurs during initialization.

Anyone have any ideas how to get around this. composite-id can also be supplied but I haven't looked into that yet.

Rich

[Richard Everhart]

I found the solution. Pretty easy really.

 <id name="counterId" column="sequence_name"/> 

The id is just the column holding the sequence name. This seemed to make things happy. I'm using postgresql by the way.

Rich

[Mark Spritzler]

Originally posted by Richard Everhart:
I found the solution. Pretty easy really.

 <id name="counterId" column="sequence_name"/> 

The id is just the column holding the sequence name. This seemed to make things happy. I'm using postgresql by the way.

Rich

Yeah, I was about to ask what DB you were using.

Sounds like you got what you were looking for, congrats.

Mark

[harsh anajwala]

Just to add doubt which I am having..

can I mention sequence name in property tag also?

<property name="count" column="seq_name" >

here seq_name will generate next value for count so is it possible?