Integrating Spring JpaRepository into JAR-RS (jersey) application generating java.lang.NullPointerException

Question

#Introduction I have a JAX-RS application using the JERSEY implementation. The container I am using is Wildfly 31.

I am working with Eclipse JPA implementation. I have introduced Springs JpaRepository to take advantage of some of their APIs but I keep on getting java.lang.NullPointerException when I try to access it.

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>backend</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>backend</name>
    <packaging>war</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.target>11</maven.compiler.target>
        <maven.compiler.source>11</maven.compiler.source>
        <junit.version>5.10.0</junit.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>jakarta.platform</groupId>
            <artifactId>jakarta.jakartaee-web-api</artifactId>
            <version>10.0.0</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.containers</groupId>
            <artifactId>jersey-container-servlet</artifactId>
            <version>3.1.3</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.media</groupId>
            <artifactId>jersey-media-json-jackson</artifactId>
            <version>3.1.3</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.inject</groupId>
            <artifactId>jersey-hk2</artifactId>
            <version>3.1.3</version>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.jpa</artifactId>
            <version>4.0.2</version>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-engine</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt-api</artifactId>
            <version>0.11.2</version>
        </dependency>
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt-impl</artifactId>
            <version>0.11.2</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt-jackson</artifactId>
            <version>0.11.2</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.mindrot</groupId>
            <artifactId>jbcrypt</artifactId>
            <version>0.4</version>
        </dependency>
        <dependency>
            <groupId>jakarta.ws.rs</groupId>
            <artifactId>jakarta.ws.rs-api</artifactId>
            <version>3.0.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
            <version>3.2.2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>6.1.3</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.4.0</version>
            </plugin>
        </plugins>
    </build>
</project>

Controller Class SecurityController.java

package com.example.backend.controllers;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.example.backend.core.jwt.APIResponse;
import com.example.backend.core.jwt.anotations.CORSAllow;
import com.example.backend.models.entity.TlRole;
import com.example.backend.models.repository.TlRoleRepository;
import jakarta.validation.Valid;
import jakarta.ws.rs.*;
import jakarta.ws.rs.core.Response;
import org.springframework.beans.factory.annotation.Autowired;

@CORSAllow
@Path("/roles")
public class SecurityController {

    @Autowired
    private TlRoleRepository tlRoleRepository;


    @GET
    public Response index() throws JsonProcessingException {
        return (new APIResponse(true, null, tlRoleRepository.findAll())).res().build();
    }
}

JpaRepository Class

package com.example.backend.models.repository;

import com.example.backend.models.entity.TlRole;
import org.springframework.data.jpa.repository.JpaRepository;

public interface TlRoleRepository extends JpaRepository<TlRole, Integer> {
}

Application Class

package com.example.backend;

import jakarta.ws.rs.ApplicationPath;
import jakarta.ws.rs.core.Application;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@ApplicationPath("/api")
@EnableJpaRepositories
@EnableTransactionManagement
public class ApplicationEntry extends Application {
}

Entity Class

package com.example.backend.models.entity;

import jakarta.persistence.*;

import java.time.OffsetDateTime;
import java.util.LinkedHashSet;
import java.util.Set;

@Entity
@Table(name = "role")
public class TlRole {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false)
    private Integer id;

    @Lob
    @Column(name = "name")
    private String name;

    @Lob
    @Column(name = "description")
    private String description;
...

}

This is the error I get when I try to hit the endpoint Error Log

14:38:55,459 ERROR [org.jboss.resteasy.core.providerfactory.DefaultExceptionMapper] (default task-1) RESTEASY002375: Error processing request GET /backend-1.0-SNAPSHOT/api/roles - com.example.backend.controllers.SecurityController.index: java.lang.NullPointerException: Cannot invoke "com.example.backend.models.repository.TlRoleRepository.findAll()" because "this.tlRoleRepository" is null
    at deployment.backend-1.0-SNAPSHOT.war//com.example.backend.controllers.SecurityController.index(SecurityController.java:31)
    at deployment.backend-1.0-SNAPSHOT.war//com.example.backend.controllers.SecurityController$Proxy$_$$_WeldSubclass.index(Unknown Source)
    at deployment.backend-1.0-SNAPSHOT.war//com.example.backend.controllers.SecurityController$Proxy$_$$_WeldClientProxy.index(Unknown Source)
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
    at java.base/java.lang.reflect.Method.invoke(Method.java:580)
    at [email protected]//org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:154)
    at [email protected]//org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:118)
    at [email protected]//org.jboss.resteasy.core.ResourceMethodInvoker.internalInvokeOnTarget(ResourceMethodInvoker.java:560)
    at [email protected]//org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTargetAfterFilter(ResourceMethodInvoker.java:452)
    at [email protected]//org.jboss.resteasy.core.ResourceMethodInvoker.lambda$invokeOnTarget$2(ResourceMethodInvoker.java:413)
    at [email protected]//org.jboss.resteasy.core.interception.jaxrs.PreMatchContainerRequestContext.filter(PreMatchContainerRequestContext.java:321)
    at [email protected]//org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTarget(ResourceMethodInvoker.java:415)
    at [email protected]//org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:378)
    at [email protected]//org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:356)
    at [email protected]//org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:70)
    at [email protected]//org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:429)
    at [email protected]//org.jboss.resteasy.core.SynchronousDispatcher.lambda$invoke$4(SynchronousDispatcher.java:240)
    at [email protected]//org.jboss.resteasy.core.SynchronousDispatcher.lambda$preprocess$0(SynchronousDispatcher.java:154)
    at [email protected]//org.jboss.resteasy.core.interception.jaxrs.PreMatchContainerRequestContext.filter(PreMatchContainerRequestContext.java:321)
    at [email protected]//org.jboss.resteasy.core.SynchronousDispatcher.preprocess(SynchronousDispatcher.java:157)
    at [email protected]//org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:229)
    at [email protected]//org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:222)
    at [email protected]//org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:55)
    at [email protected]//org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:51)
    at [email protected]//jakarta.servlet.http.HttpServlet.service(HttpServlet.java:614)
    at [email protected]//io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:74)
    at [email protected]//io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
    at [email protected]//io.undertow.servlet.handlers.ServletChain$1.handleRequest(ServletChain.java:68)
    at [email protected]//io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
    at [email protected]//org.wildfly.elytron.web.undertow.server.ElytronRunAsHandler.lambda$handleRequest$1(ElytronRunAsHandler.java:68)
    at [email protected]//org.wildfly.security.auth.server.FlexibleIdentityAssociation.runAsFunctionEx(FlexibleIdentityAssociation.java:103)
    at [email protected]//org.wildfly.security.auth.server.Scoped.runAsFunctionEx(Scoped.java:161)
    at [email protected]//org.wildfly.security.auth.server.Scoped.runAs(Scoped.java:73)
    at [email protected]//org.wildfly.elytron.web.undertow.server.ElytronRunAsHandler.handleRequest(ElytronRunAsHandler.java:67)
    at [email protected]//io.undertow.servlet.handlers.RedirectDirHandler.handleRequest(RedirectDirHandler.java:68)
    at [email protected]//io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:117)
    at [email protected]//io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
    at [email protected]//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at [email protected]//io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
    at [email protected]//io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
    at [email protected]//io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
    at org.wildfly.security.elytron-web.undertow-server-servlet@4.0.0.Final//org.wildfly.elytron.web.undertow.server.servlet.CleanUpHandler.handleRequest(CleanUpHandler.java:38)
    at [email protected]//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at [email protected]//org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:44)
    at [email protected]//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at [email protected]//org.wildfly.extension.undertow.deployment.GlobalRequestControllerHandler.handleRequest(GlobalRequestControllerHandler.java:51)
    at [email protected]//io.undertow.servlet.handlers.SendErrorPageHandler.handleRequest(SendErrorPageHandler.java:52)
    at [email protected]//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at [email protected]//io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:276)
    at [email protected]//io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:135)
    at [email protected]//io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:132)
    at [email protected]//io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
    at [email protected]//io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
    at [email protected]//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1413)
    at [email protected]//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1413)
    at [email protected]//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1413)
    at [email protected]//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1413)
    at [email protected]//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1413)
    at [email protected]//io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:256)
    at [email protected]//io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:101)
    at [email protected]//io.undertow.server.Connectors.executeRootHandler(Connectors.java:393)
    at [email protected]//io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:859)
    at [email protected]//org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
    at [email protected]//org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1990)
    at [email protected]//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1486)
    at [email protected]//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1377)
    at [email protected]//org.xnio.XnioWorker$WorkerThreadFactory$1$1.run(XnioWorker.java:1282)
    at java.base/java.lang.Thread.run(Thread.java:1583)