[bv-dev] BVAL-234 @NotNull @Id for JPA and Bean Validation

[Emmanuel Bernard]

I was not thinking of validating the object id property after it has been inserted but simply avoid validation in pre-persist altogether.
We could try and see if your approach is feasible indeed but the benefit would be quite minimal as we are talking about a generated id.

You don't need 2 PC, id generation is still done within the same transaction - at flush time to be specific. Insertion out of transaction
is not possible in JPA.

On 15 mai 2012, at 11:57, Sebastian Thomschke wrote:

> I would prefer option 3 if possible. But would this require XA 
> transactions (two phase commit) because JPA would trigger the ID 
> validation after the record has been created and if invalid needs to 
> rollback the commit.
> 
> Seb
> 
> On 15.05.2012 10:22, Emmanuel Bernard wrote:
>> There is an annoyance when using JPA and Bean Validation today. I worked out a proposal. Please let me know what you think
>> 
>> http://beanvalidation.org/proposals/BVAL-234/
>> 
>> --- (copied here for convenience) ---
>> 
>> [Link to JIRA ticket][jira]
>> See also [NetBeans issue][netbeans]
>> 
>> ## Problem description
>> 
>> Today when a property marked @Id @GeneratedValue is also marked @NotNull, it will fail if the identity generation is post-insert
>> in the database. This can be the case if the underlying table is using column id generation for example.
>> 
>> The id property is thus null when Bean Validation is executed during the pre-persist phase and a constraint
>> violation is raised.
>> 
>> ## Solutions
>> 
>> ### 1. User adjusts
>> 
>> One option is to stay put and consider the behavior valid. The user can work around that by:
>> 
>> - creating a `com.acme.groups.Created` group
>> - marking the `@NotNull` annotation as belonging to the group
>> - override the groups in `persistence.xml` to validate `Created` accordingly
>> 
>> Here is the snipped of the `persistence.xml` file
>> 
>>     <property name="javax.persistence.validation.group.pre-persist"
>>               value="javax.validation.groups.Default"/>
>>     <property name="javax.persistence.validation.group.pre-update"
>>               value="javax.validation.groups.Default,com.acme.groups.Created"/>
>> 
>> 
>> ### 2 User adjusts with some help
>> 
>> We could use option 1 but have JPA provide the created group: `javax.persistence.validation.groups.Created`
>> 
>> ### 3. Have JPA disable validation of id properties at pre-persist
>> 
>> JPA could disable validation on id properties if in pre-persist and if the generated value is not created yet.
>> Note that we disable all validations - not simply `@NotNull` - as it does not make much sense to execute other
>> validations when a property is null.
>> 
>> `TraversableResolver` can be used to solve the problem as `isReachable` can stop the processing of a property.
>> 
>> ### Conclusions
>> 
>> Option 3 seems the most reasonable but it could be complicated at the JPA level.
>> Before going to the JPA EG, let's discuss the situation here.
>> 
>> ### Questions remaining
>> 
>> - should the `Created` groups be renamed?
>> - is that correct to sneakily disable @NotNull constraint validation?
>> 
>> 
>> [netbeans]: http://netbeans.org/bugzilla/show_bug.cgi?id=197845#c3
>> [jira]: https://hibernate.onjira.com/browse/BVAL-234
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