null database fields and primitive types

musicstar · **Posted:** Sat Apr 17, 2004 5:10 pm

Simple question:

How does hibernate handle a field that maps to a primitive type when it is null?

Feature questions/request:

Does the ability to specify on the hibernate descriptor a value to use if the field return was null sould useful? (i.e. null-value="-1")

Martin

michael · **Posted:** Sat Apr 17, 2004 7:36 pm

You get an exception when trying to load a null value into a primitive type. You can however use a custom UserType very easily to handle such value conversions.

musicstar · **Posted:** Mon Apr 19, 2004 9:47 am

Does the potential feature sound useful? Making a custom UserType to handle all the primitives and mapping them into all my value objects seems cumbersome. I would be willing to develope this, but would need a bit of guidence as to the best place to put this.

I personally hate nulls in the database, but there are situations where they are unavoidable....

michael · **Posted:** Mon Apr 19, 2004 10:08 am

IMHO the existing solution is sufficient, you can however enter a feature request in JIRA if you want.

gavin · **Posted:** Mon Apr 19, 2004 10:14 am

Don't create a feature request, since I will just reject it.

musicstar · **Posted:** Mon Apr 19, 2004 10:48 am

Just out of curiousity, Gavin, why would you reject it outright? In your opinion is the better design to always use the Object wrapper for primitives on a value object?

Martin

emmanuel · **Posted:** Tue Apr 20, 2004 9:27 am

Because it's only here to solve a specific case and UserType is way more powerful.
Such specific features are quite common and would pollute the mapping file quickly

fabiolourencetti · **Posted:** Tue Apr 20, 2004 2:46 pm

But supose you have lots of tables with numeric columns mapped to primitive types and these columns have different default values.

This is a common scenario.

Shoul I create a custom type for every diferent default value?

I agree with martin. I think that there should by a parameter like (null-value="0")

Fabio

michael · **Posted:** Tue Apr 20, 2004 7:13 pm

You have to create a custom UserType for every case. How many default values do you have, there are not many sensible cases besides -1 and 0. This might probably become easier in future versions with parametrizable UserTypes.

musicstar · **Posted:** Wed Apr 21, 2004 7:15 am

I have scenarios where it's not defaulting to 0 or -1, but also Integer.MAX_VALUE and Integer.MIN_VALUE.

Can you do primitive types using UserTypes? What is the intended functionality of a parametrizable UserTypes? I have a need for this, so I would be willing again to help develop this? Is there a JIRA for this feature?

Martin

fabiolourencetti · **Posted:** Thu Apr 22, 2004 8:42 am

I work on a big Human Resource system. There are more than 900 tables.

I have the data dictionary stored in tables. I've searched for columns whose default values are different than 0, -1 and the amount is 40 different default values.

I think this new "null-value" parameter would help a lot and it's an additional resource for hibernate

Fabio