java.lang.ClassNotFoundException: org.postgresql.Driver

[pmenage]

Hi Everybody,

I am new to Wildfly / postgresql development. I tried to develop a small java application connecting to a postgresql database which works correctly. I moved the code in a EJB project running on WildFly 16. I add the module.xml file and changed the standalone.xml file as I found on various websites. The EJB project is successfully installed on WildFlly. But when I run a java application calling the EJB, I got error:

WFLYEJB0442: Unexpected Error

......

Caused by: java.lang.NoClassDefFoundError: org/postgresql/Driver

......

Caused by: java.lang.ClassNotFoundException: org.postgresql.Driver from [Module "deployment.MyEjb.jar" from Service Module Loader]

the content of module.xml is :

<?xml version="1.0" encoding="utf-8" ?>

<module xmlns="urn:jboss:module:1.3" name="org.postgresql">

    <resources>

    <!--the name of your driver -->

        <resource-root path="postgresql-42.2.6.jar"/>

    </resources>

    <dependencies>

        <module name="javax.api"/>

        <module name="javax.transaction.api"/>

    </dependencies>

</module>

Seems simple, but not for me even after several days of battle.

Patrick

[jaikiran]

Are you doing any Class.forName(...) calls on the JDBC driver from within your application? If not, I don't see why it would try to load that class in the context of your deployment classloader.

If you are indeed referring to the JDBC driver class within your application, then add a module dependency of the JDBC module (org.postgresql in this example), to your application (myejb.jar). You can do that by following the instructions here Class Loading in WildFly - Latest WildFly Documentation - Project Documentation Editor  (see section "Dependencies: Manifest Entries")

[pmenage]

Thank you for your answer. I had the solution from an answer received from Stack Overflow (https://stackoverflow.com/questions/56930075/why-wildfly-does-not-find-the-postgresql-driver), which was to use jboss-deployment-structure file which I put in folder ejbModule\Meta-Inf. its content is:

<?xml version="1.0" encoding="UTF-8"?>

<jboss-deployment-structure>

  <deployment>

      <dependencies>

         <module name="org.postgresql"/>

      </dependencies>

    </deployment>

</jboss-deployment-structure>

To summarise, I had to create a module.xml, file a  jboss-deployment-structure.xml file and to modify the standalone.xml file.

Regards

Patrick