Wildfly Postgres JDBC module issue - postgresql

Question

I have postgres jdbc driver configured as module in Wildfly 10. What I am trying to do, is to use that driver as dependency in application that will be deployed on the server - so in application, I mark this dependency as provided (in pom.xml file) but it seems to be not working.
Current configuration:
Wildfly postgres module is added at wildfly-10.1.0.Final\modules\org\postgresql\main where there is: postgresql-9.4-1206-jdbc4.jar and module.xml with following content:
<module xmlns="urn:jboss:module:1.1" name="org.postgresql">
<resources>
<resource-root path="postgresql-9.4-1206-jdbc4.jar"/>
</resources>
<dependencies>
<module name="javax.api"/>
<module name="javax.transaction.api"/>
</dependencies>
</module>
Module is used to define datasource. To this point, everything is working well - with hibernate help tables are happily mapped to entities. Except one thing:
I started to map postgres-jsonb columns with use of javax.persistence.AttributeConverter and following happens:
Scenario 1
When I use postgresql-9.4-1206-jdbc4.jar as a provided (in pom.xml - deployed application), I get following error trying to convert anything:
Caused by: java.lang.ClassNotFoundException: org.postgresql.util.PGobject from [Module "deployment.priject-1.0.1.ear.project.data-1.0.1-SNAPSHOT.jar:main" from Service Module Loader]
at org.jboss.modules.ModuleClassLoader.findClass(ModuleClassLoader.java:198)
at org.jboss.modules.ConcurrentClassLoader.performLoadClassUnchecked(ConcurrentClassLoader.java:363)
at org.jboss.modules.ConcurrentClassLoader.performLoadClass(ConcurrentClassLoader.java:351)
at org.jboss.modules.ConcurrentClassLoader.loadClass(ConcurrentClassLoader.java:93)
... 269 more
Scenario 2
When I use postgresql-9.4-1206-jdbc4.jar with default scope, there is following error:
Caused by: java.lang.ClassCastException: org.postgresql.util.PGobject cannot be cast to org.postgresql.util.PGobject
at com.project.entity.util.converters.JSONBTypeConverter.convertToEntityAttribute(JSONBTypeConverter.java:33)
at com.project.entity.util.converters.JSONBTypeConverter.convertToEntityAttribute(JSONBTypeConverter.java:1)
at org.hibernate.type.descriptor.converter.AttributeConverterSqlTypeDescriptorAdapter$2.doConversion(AttributeConverterSqlTypeDescriptorAdapter.java:140)
... 266 more
Which means: class loader load the same jar two times, and can not cast this object to itself.
Question: Why provided scope of the dependency does not work for manually added (to wildfly) postgres driver? (I guess that would be the solution for me)

Answer 1

You need to use a jboss-deployment-structure.xml to add the module dependency to your deployment.
<jboss-deployment-structure>
<deployment>
<dependencies>
<module name="org.postgresql" />
</dependencies>
</deployment>
<sub-deployment name="project.data-1.0.1-SNAPSHOT.jar">
<dependencies>
<module name="org.postgresql" />
</dependencies>
</sub-deployment>
</jboss-deployment-structure>
Note the module dependency on the EAR may not be required. It just depends on how your EAR is setup.
Another option would be to add a Dependencies manifest entry. Since you're using Maven you could just use the maven-jar-plugin (since it appears this is a JAR inside an EAR) to create the entry.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifestEntries>
<Dependencies>org.postgresql</Dependencies>
</manifestEntries>
</archive>
</configuration>
</plugin>