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From opengloves <openglo...@gmail.com>
Subject Re: OpenJPA-2.0.0-snapshot Question with @ManyToMany
Date Tue, 02 Jun 2009 05:51:52 GMT

Hi,
Thanks for your response.
I hardcoded is just for test @ManyToMany and see the effect. @GeneratedValue
is not the point of this issue.
I also do not think this is the bug of OpenJPA, and I had been modified the
code like your advice before, and It didn't passed test either. because the
test code is passed, but it didn't do the right thing because the data is
not insert into the table STUDENT_TEACHER, this is strange, and I also test
the hibernate without if block and it works, and I tested the method
testPersistJoinTable() twice and the table is also contain one record. and
this is good, this is the META-INF/persistence.xml about hibernate
<persistence-unit name="sample" transaction-type="RESOURCE_LOCAL">
		<class>org.sample.demo.jpa.entity.manytomany.Student</class>
		<class>org.sample.demo.jpa.entity.manytomany.Teacher</class>
		<properties>
			<property name="hibernate.dialect"
value="org.hibernate.dialect.DerbyDialect"/>		
			<property name="hibernate.connection.url"
value="jdbc:derby://localhost:1527/sample;create=true" />
			<property name="hibernate.connection.driver_class"
value="org.apache.derby.jdbc.ClientDriver" />
			<property name="hibernate.connection.username" value="user" />
			<property name="hibernate.connection.password" value="secret" />
			<property name="hibernate.hbm2ddl.auto" value="update"/>			
		</properties>
	</persistence-unit>
Jar Environment: antlr-2.7.6, commons-collections-3.1, dom4j-1.6.1,
ejb3-persistence, hibernate3, hibernate-annotations,
hibernate-cglib-repack-2.1_3, hibernate-commons-annotations,
hibernate-entitymanager, javassist-3.4.GA, jta-1.1, log4j-1.2.15,
slf4j-api-1.5.2, slf4j-log4j12-1.5.0.
Other environment and codes are the same.(Student.java, Teacher.java,
ManyToManyTest.java are the same)

After modified the code, I think this is strange: the test is passed and the
data is not insert into the table.
And I come here, find help. Or maybe this is a bug? 
I think add this if block is the provider dependence, maybe.

------
Thanks
Open Gloves


Jeremy Bauer wrote:
> 
> Hi,
> 
> Interesting that this works on Hibernate.  The first potential issue I
> found
> in the test is that it uses a hardcoded id and your entities are annotated
> with @GeneratedValue.  Depending on how the value is generated, the values
> could be different between test runs and providers.  Storing away the id
> of
> the persisted entities (in static fields, for example) is a safer and more
> consistent way to make sure the test accesses the same entities in future
> test variations.
> 
> The NPE is the result of the student.teachers collection being null. 
> While
> the class contains code to set it to new HashSet upon construction,
> OpenJPA
> sets it to null after the find operation - since the set did not contain
> any
> elements when Student was persisted.  Modifying the addTeacher method as
> below corrected the NPE and the test passed.
> 
>        public void addTeacher(Teacher teacher) {
>            if (teachers == null)
>                teachers = new HashSet<Teacher>();
>            this.teachers.add(teacher);
>        }
> 
> Based on the behavior I've seen, I do not think this is a bug in OpenJPA.
> While I haven't tested with Hibernate, I suspect it is just a difference
> in
> how empty/null collections are stored and initialized by each provider.
> 
> hth,
> -Jeremy
> 
> 

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