Replacement for PersistentEnum - non Serializable UserType

ralf_edmund · **Joined:** Mon Feb 16, 2004 9:19 am **Posts:** 11

Due to the deprecation of the PersistentEnum interface a tried to implement a replacement by implementing a UserType.

This solution requires the Enumeration to be Serializable but this is in my opinion not useful for Enumerations.

What is a useable replacement for PersistentEnum ???

christian · **Posted:** Thu Apr 29, 2004 10:24 am

A UserType.

ikar · **Joined:** Thu Apr 29, 2004 10:55 am **Posts:** 1

As compared with PersistentEnum handling in 2.1.2-, I liked the way persistent enums are implemented in Castor: enum clas just has to contain a method valueOf(String) and does not have to implement any interface. It's so easy to use! Why not using something similar in hibernate?

michael · **Posted:** Thu Apr 29, 2004 11:11 am

Why shouldn't your enums be serializable? You never want to move objects containing them between tiers or put them in a HttpSession? I don't think this is a limitation.

ralf_edmund · **Joined:** Mon Feb 16, 2004 9:19 am **Posts:** 11

michael wrote:

Why shouldn't your enums be serializable? You never want to move objects containing them between tiers or put them in a HttpSession? I don't think this is a limitation.

My Class has been implemented as a typesafe enum. Therefore it has no public constructor. Because these classes are not Serializable i get ClassCastExceptions in deepCopy() because the returned Object gets typecasted to Serializable.

ralf_edmund · **Joined:** Mon Feb 16, 2004 9:19 am **Posts:** 11

christian wrote:

A UserType.

I've implemented a UserType that reimplements the PersistentEnum interface.
I've changed (some of) my HQL queries to use this new type but i get a bunch of ClassCastExceptions.

Probably it would have been a good idea to refactor my Enums one class at a time...

michael · **Posted:** Thu Apr 29, 2004 11:24 am

Make it Serializable if you get an exception. The requirement is there for a reason.

ralf_edmund · **Joined:** Mon Feb 16, 2004 9:19 am **Posts:** 11

michael wrote:

Make it Serializable if you get an exception. The requirement is there for a reason.

If this is a requirement, this should documented in the interface and documentation.

The Javadoc for UserType explizitely does not require the Types to be Serializable.

michael · **Posted:** Thu Apr 29, 2004 11:43 am

Quote:

The actual class mapped by a UserType may be just about anything. However, if it is to be cacheable by JCS, it must be serializable.

There is no other place which would require the class to be serializable, and certainly not in deepCopy()

ralf_edmund · **Joined:** Mon Feb 16, 2004 9:19 am **Posts:** 11

michael wrote:

Quote:

The actual class mapped by a UserType may be just about anything. However, if it is to be cacheable by JCS, it must be serializable.

There is no other place which would require the class to be serializable, and certainly not in deepCopy()

The following snippet ist part of AbstractType.class:

Code:

    public Serializable disassemble(Object value,
SessionImplementor session)
        throws HibernateException
    {
        if(value == null)
            return null;
        else
            return (Serializable)deepCopy(value);
    }

ralf_edmund · **Joined:** Mon Feb 16, 2004 9:19 am **Posts:** 11

michael wrote:

Make it Serializable if you get an exception. The requirement is there for a reason.

I spent the time to make them Serializable and - implementig readResolve() - still kept their uniqueness. Now everyting again works as expected.

But there is still a question left:
It was convenient to use the members of PersistentEnum as a selection criteria in HQL queries. Now i have to use "query.setParamenter("xxx", value, Hibernate.custom())" instead. Is there any better way to specify them in my queries?

gavin · **Posted:** Fri Apr 30, 2004 4:36 am

Quote:

The following snippet ist part of AbstractType.class:

disassemble() is only called when caching the data in the second-level cache, as Micheal said.