[Hibernate-issues] [Hibernate-JIRA] Commented: (HHH-1713) AbstractEntityPersister causes an exception when a row in a joined table is missing with fetch="select"

[Mike D. (JIRA) <no...@at...>]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-1713?page=comments#action_22961 ] 

Mike Dillon commented on HHH-1713:
----------------------------------

There is another unchecked use of ResultSet.next() in the same class that should probably be checked as well. That one is in initializeLazyPropertiesFromDatastore().

> AbstractEntityPersister causes an exception when a row in a joined table is missing with fetch="select"
> -------------------------------------------------------------------------------------------------------
>
>          Key: HHH-1713
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-1713
>      Project: Hibernate3
>         Type: Bug

>   Components: core
>     Versions: 3.1.3, 3.2.0 cr1
>  Environment: Hibernate 3.1.3, 3.2.0cr1
> Oracle 9i (using odjbc14.jar from Oracle 10.1.0.4)
>     Reporter: Mike Dillon
>     Priority: Minor
>  Attachments: AbstractEntityPersister.java.patch
>
>
> When using the <join> mapping, the behavior of AbstractEntityPersister when the joined row is missing is not consistent between fetch="join" and fetch="select".
> When fetch="join" and the row is missing, the AbstractEntityPersister simply sets all the outer joined fields to null since that's what comes back from the database. However, when fetch="select" and the row is missing, an SQLException is thrown. The reason is that the call to ResultSet.next() is not checked to see if a row is available before calling ResultSet.getXXXX(). In our Oracle enviroment, this resulted in a cryptic JDBC error about an "Exhausted Resultset".
> The fix is to check the return value of ResultSet.next(). I have attached a patch with a proposed fix for this issue. To be consistent with the current behavior of fetch="join", it explicitly sets all fields that come from the "sequential select" to null when the select does not produce any rows. This contradicts the hibernate-mapping DTD which says that the "optional" attribute on <join> defaults to false, but since that attribute is undocumented and the current implementation doesn't seem to respect this attribute even when fetch="join", I decided to be consistent with the actual semantics of fetch="join".
> The behavior of the optional attibute probably needs to be fixed in both cases, but I didn't address that with my patch. It seems that optional only works as advertised when Hibernate is able to produce a query with a single polymorphic join and can use an inner join instead of a left outer join.
> My patch was created against Hibernate 3.1.3, but I looked at the same code in 3.2.0cr1 and it has not changed.

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