I am getting an Status 500 Internal Error from my backend with Spring Boot

Question

So I am testing my employee manager app in postman, and my delete get and all of the other requests work, but my update(put) request doesn't. I have also made the front end in Angular that is connected to the BE, but I think the Angular part isn't making the problem, if someone thinks that it is, please let me know I will gladly post that code also.
I am not sure how to fix this error, this is the code:

Employee Service

@Service("employeeService")
@Transactional
public class EmployeeService {
    private final EmployeeRepo employeeRepo;

    @Autowired
    public EmployeeService(EmployeeRepo employeeRepo) {
        this.employeeRepo = employeeRepo;
    }

    public Employee addEmployee(Employee employee) {
        employee.setEmployeeCode(UUID.randomUUID().toString());
        return employeeRepo.save(employee);
    }

    public List<Employee> findAllEmployees() {
        return employeeRepo.findAll();
    }

    public Employee updateEmployee(Employee employee) {
        return employeeRepo.save(employee);
    }

    public Employee findEmployeeById(Long id) {
        return employeeRepo.findEmployeeById(id)
                .orElseThrow(() -> new UserNotFoundException("User by id " + id + " was not found"));
    }
     public void deleteEmployee(Long id){
        employeeRepo.deleteById(id);
         }
}

Employee Resource

@RestController
@RequestMapping("/employee")
public class EmployeeResource {
    private final EmployeeService employeeService;

    public EmployeeResource(EmployeeService employeeService) {
        this.employeeService = employeeService;
    }

    @GetMapping("/all")
    public ResponseEntity<List<Employee>> getAllEmployees () {//vratice http responce u cijem body-u ce biti lista zaposlenih
        List<Employee> employees = employeeService.findAllEmployees();
        return new ResponseEntity<>(employees, HttpStatus.OK);
    }

    @GetMapping("/find/{id}")
    public ResponseEntity<Employee> getEmployeeById (@PathVariable("id") Long id) {
        Employee employee = employeeService.findEmployeeById(id);
        return new ResponseEntity<>(employee, HttpStatus.OK);
    }

    @PostMapping("/add")
    public ResponseEntity<Employee> addEmployee(@RequestBody Employee employee) {//posto u JSON formatu vraca ceo kao body
        Employee newEmployee = employeeService.addEmployee(employee);
        return new ResponseEntity<>(newEmployee, HttpStatus.CREATED);
    }

    @PutMapping("/update")
    public ResponseEntity<Employee> updateEmployee(@RequestBody Employee employee) {
        Employee updateEmployee = employeeService.updateEmployee(employee);
        return new ResponseEntity<>(updateEmployee, HttpStatus.OK);
    }

    @DeleteMapping("/delete/{id}")
    public ResponseEntity<?> deleteEmployee(@PathVariable("id") Long id) {
        employeeService.deleteEmployee(id);
        return new ResponseEntity<>(HttpStatus.OK);
    }
}

Employee Repository

@Repository
public interface EmployeeRepo extends JpaRepository<Employee, Long> {
   // employeeRepo.deleteById(Long id);
    Optional<Employee> findEmployeeById(Long id);
}

Employee

@Entity
public class Employee implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(nullable = false, updatable = false)
    private Long id;
    private String name;
    private String email;
    private String jobTitle;
    private String phoneNumber;
    private String imageUrl;
    @Column(nullable = false, updatable = false)
    private String employeeCode;

    public Employee() {}

    public Employee(String name, String email, String jobTitle, String phoneNumber, String imageUrl, String employeeCode) {
        this.name = name;
        this.email = email;
        this.jobTitle = jobTitle;
        this.phoneNumber = phoneNumber;
        this.imageUrl = imageUrl;
        this.employeeCode = employeeCode;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getJobTitle() {
        return jobTitle;
    }

    public void setJobTitle(String jobTitle) {
        this.jobTitle = jobTitle;
    }

    public String getPhoneNumber() {
        return phoneNumber;
    }

    public void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }

    public String getImageUrl() {
        return imageUrl;
    }

    public void setImageUrl(String imageUrl) {
        this.imageUrl = imageUrl;
    }

    public String getEmployeeCode() {
        return employeeCode;
    }

    public void setEmployeeCode(String employeeCode) {
        this.employeeCode = employeeCode;
    }

    @Override
    public String toString() {
        return "Employee{" +
                "Id=" + id +
                ", name='" + name + '\'' +
                ", email='" + email + '\'' +
                ", jobTitle='" + jobTitle + '\'' +
                ", phoneNumber='" + phoneNumber + '\'' +
                ", imageUrl='" + imageUrl + '\'' +
                ", employeeCode='" + employeeCode + '\'' +
                '}';
    }
}

Stack Trace

org.hibernate.PropertyValueException: not-null property references a null or transient value : com.cjufi.employeemanager.model.Employee.employeeCode
    at org.hibernate.engine.internal.Nullability.checkNullability(Nullability.java:111) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.engine.internal.Nullability.checkNullability(Nullability.java:55) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.action.internal.AbstractEntityInsertAction.nullifyTransientReferencesIfNotAlready(AbstractEntityInsertAction.java:116) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:72) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:645) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:282) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:263) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:317) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:330) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:287) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:123) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:55) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:107) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:756) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:742) ~[hibernate-core-5.6.10.Final.jar:5.6.10.Final]
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:577) ~[na:na]
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:362) ~[spring-orm-5.3.22.jar:5.3.22]
    at jdk.proxy2/jdk.proxy2.$Proxy96.persist(Unknown Source) ~[na:na]
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:577) ~[na:na]
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:311) ~[spring-orm-5.3.22.jar:5.3.22]
    at jdk.proxy2/jdk.proxy2.$Proxy96.persist(Unknown Source) ~[na:na]
    at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:666) ~[spring-data-jpa-2.7.2.jar:2.7.2]
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:577) ~[na:na]
    at org.springframework.data.repository.core.support.RepositoryMethodInvoker$RepositoryFragmentMethodInvoker.lambda$new$0(RepositoryMethodInvoker.java:289) ~[spring-data-commons-2.7.2.jar:2.7.2]
    at org.springframework.data.repository.core.support.RepositoryMethodInvoker.doInvoke(RepositoryMethodInvoker.java:137) ~[spring-data-commons-2.7.2.jar:2.7.2]
    at org.springframework.data.repository.core.support.RepositoryMethodInvoker.invoke(RepositoryMethodInvoker.java:121) ~[spring-data-commons-2.7.2.jar:2.7.2]
    at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:530) ~[spring-data-commons-2.7.2.jar:2.7.2]
    at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:286) ~[spring-data-commons-2.7.2.jar:2.7.2]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:640) ~[spring-data-commons-2.7.2.jar:2.7.2]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:164) ~[spring-data-commons-2.7.2.jar:2.7.2]
    at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:139) ~[spring-data-commons-2.7.2.jar:2.7.2]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:81) ~[spring-data-commons-2.7.2.jar:2.7.2]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123) ~[spring-tx-5.3.22.jar:5.3.22]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388) ~[spring-tx-5.3.22.jar:5.3.22]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) ~[spring-tx-5.3.22.jar:5.3.22]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137) ~[spring-tx-5.3.22.jar:5.3.22]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:174) ~[spring-data-jpa-2.7.2.jar:2.7.2]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215) ~[spring-aop-5.3.22.jar:5.3.22]
    at jdk.proxy2/jdk.proxy2.$Proxy100.save(Unknown Source) ~[na:na]
    at com.cjufi.employeemanager.service.EmployeeService.updateEmployee(EmployeeService.java:34) ~[classes/:na]
    at com.cjufi.employeemanager.service.EmployeeService$$FastClassBySpringCGLIB$$f9421ab5.invoke(<generated>) ~[classes/:na]
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) ~[spring-core-5.3.22.jar:5.3.22]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:793) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123) ~[spring-tx-5.3.22.jar:5.3.22]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388) ~[spring-tx-5.3.22.jar:5.3.22]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) ~[spring-tx-5.3.22.jar:5.3.22]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) ~[spring-aop-5.3.22.jar:5.3.22]
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:708) ~[spring-aop-5.3.22.jar:5.3.22]
    at com.cjufi.employeemanager.service.EmployeeService$$EnhancerBySpringCGLIB$$83e2c27e.updateEmployee(<generated>) ~[classes/:na]
    at com.cjufi.employeemanager.resource.EmployeeResource.updateEmployee(EmployeeResource.java:40) ~[classes/:na]
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:577) ~[na:na]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-5.3.22.jar:5.3.22]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) ~[spring-web-5.3.22.jar:5.3.22]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.22.jar:5.3.22]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.22.jar:5.3.22]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.22.jar:5.3.22]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.22.jar:5.3.22]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1070) ~[spring-webmvc-5.3.22.jar:5.3.22]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.22.jar:5.3.22]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.22.jar:5.3.22]
    at org.springframework.web.servlet.FrameworkServlet.doPut(FrameworkServlet.java:920) ~[spring-webmvc-5.3.22.jar:5.3.22]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:684) ~[tomcat-embed-core-9.0.65.jar:4.0.FR]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.22.jar:5.3.22]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.65.jar:4.0.FR]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.65.jar:9.0.65]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:91) ~[spring-web-5.3.22.jar:5.3.22]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.22.jar:5.3.22]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.22.jar:5.3.22]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.22.jar:5.3.22]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.22.jar:5.3.22]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.22.jar:5.3.22]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.22.jar:5.3.22]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117) ~[spring-web-5.3.22.jar:5.3.22]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:890) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1789) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.65.jar:9.0.65]
    at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]

Hibernate: select employee0_.id as id1_0_, employee0_.email as email2_0_, employee0_.employee_code as employee3_0_, employee0_.image_url as image_ur4_0_, employee0_.job_title as job_titl5_0_, employee0_.name as name6_0_, employee0_.phone_number as phone_nu7_0_ from employee employee0_
2022-08-21 02:01:02.830  WARN 7332 --- [l-1 housekeeper] com.zaxxer.hikari.pool.HikariPool        : HikariPool-1 - Thread starvation or clock leap detected (housekeeper delta=44m1s400ms600µs500ns).

Example of my JSON that I put
{ "id": 17, "email": "cjufi@gmail.com", "imageUrl": "bootdey.com/img/Content/avatar/avatar1.png", "jobTitle": "Java", "name": "cjufi", "phoneNumber": "555333" }

Answer 1

If I'm reading you correctly, you don't want employeeCode to be updatable, as defined by your Entity with @Column(nullable = false, updatable = false).

The other answers are wrong, you don't have to add that field to your JSON when you're only updating. But this fails on your PUT request as you don't attempt to find the existing Employee first, but simply try to update with an entirely new object (which does have that null field that shouldn't be nullable by then) and are re-using your Entity as an input object for your Controller.

The usual way to do this would be to create a DTO specifically for this, then try to find the existing database entity based on the id and update that.

Another problem with your current approach is that there's nothing stopping someone from just passing an entirely new Employee with a new id to that update endpoint, and creating their own id that way.

You could also require that id to be in the request path so you don't have a PUT request on the main endpoint or a separate /update path, but rather have a structure like /employees/{id} where you can then parse the path and first attempt to find that employee with the parsed id.

Small example:

@PutMapping(value = "/{id}", consumes = APPLICATION_JSON_VALUE)
public ResponseEntity<EmployeeOutputDTO> updateEmployee(
    @PathVariable("id") UUID id,
    @RequestBody @Valid EmployeeInputDTO employeeDTO) {
    EmployeeOutputDTO responseDTO = employeeService.apiUpdate(id, employeeDTO);
    return ResponseEntity.ok(responseDTO);
}

public EmployeeOutputDTO apiUpdate(UUID id, EmployeeInputDTO employeeDTO) {
    log.info("Updating employee");

    Employee existingEmployee = findOrThrowNotFoundException(id);
    // ...do update
}

Answer 2

The JSON payload what you are using to update your entity :

{ "id": 17, "email": "cjufi@gmail.com", "imageUrl": "bootdey.com/img/Content/avatar/avatar1.png", "jobTitle": "Java", "name": "cjufi", "phoneNumber": "555333" }

Does not contain employeeCode. So it's like you are passing NULL value but in your DB you said it should be non-null. That's why you are getting error. You can either remove the constraints for the employeeCode column or provide the actual value when updating

Answer 3

you give the employeeCode a null, but it was defined not null in database