Spring Boot REST App. You can't link bean with service in MVC controller

Question

Good afternoon. I'm new to Java please be patient, I want to get a list of entities via REST. but I can't link bean with service in MVC controller. Below is my code.

Repository

public interface CustomerRepository extends JpaRepository<Customer, Long> {}

Service interface

public interface CustomerService {
    Page<CustomerRsDto> getAll(Pageable pageable);
}

Implementation of service interface

@Service
@RequiredArgsConstructor
public class CustomerServiceImpl implements CustomerService {
    private final CustomerRepository customerRepository;
    private final CustomerMapper customerMapper;

    @Override
    @Transactional
    public Page<CustomerRsDto> getAll(Pageable pageable) {
        List<Customer> dbCustomers = customerRepository.findAll();
        List<CustomerRsDto> listCustomers = null;

        dbCustomers.forEach(dbCustomer -> {
            listCustomers.add(customerMapper.toRsDto(dbCustomer));
        });

        Page<CustomerRsDto> rsCustomers = new PageImpl<CustomerRsDto>(listCustomers);

        return rsCustomers;
    }
}

REST Controller

@RestController
@RequiredArgsConstructor
@RequestMapping("/customers")
@Api(tags = "customers", value = "Customres")
public class CustomersController {
    private CustomerService customerService;

    @GetMapping
    @ApiOperation(tags = "customers", value = "Get all")
    public Page<CustomerRsDto> getAll(Pageable pageable) {
        if (isNull(customerService)) {
            System.out.println("Not linked bean?");
        }
        return customerService.getAll(pageable);
    }
}

This code compiles, but when I call the curl controller I get a message that bin autocoupling has not happened and the object variable points to null.

Curl command

curl -X GET "http://localhost:8080/customers?pageNumber=1&pageSize=5" -H "accept: */*" -H 'authorization: Basic YWRtaW46YWRtaW4='

Message from the servlet container

2020-11-12 14:30:19.958  INFO 7836 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 5 ms
Not linked bean?
2020-11-12 14:30:20.407 ERROR 7836 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause

java.lang.NullPointerException: null
    at <My Packages>.rest.CustomersController.getAll(CustomersController.java:31) ~[classes/:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878) ~[spring-webmvc-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792) ~[spring-webmvc-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:626) ~[tomcat-embed-core-9.0.39.jar:4.0.FR]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) ~[tomcat-embed-core-9.0.39.jar:4.0.FR]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.39.jar:9.0.39]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:320) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:126) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:90) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:118) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:158) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilterInternal(BasicAuthenticationFilter.java:204) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.authentication.ui.DefaultLogoutPageGeneratingFilter.doFilterInternal(DefaultLogoutPageGeneratingFilter.java:52) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter.doFilter(DefaultLoginPageGeneratingFilter.java:216) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:200) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:92) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:77) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178) ~[spring-security-web-5.3.5.RELEASE.jar:5.3.5.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.10.RELEASE.jar:5.2.10.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.keycloak.adapters.tomcat.AbstractAuthenticatedActionsValve.invoke(AbstractAuthenticatedActionsValve.java:67) ~[spring-boot-container-bundle-10.0.2.jar:10.0.2]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.keycloak.adapters.tomcat.AbstractKeycloakAuthenticatorValve.invoke(AbstractKeycloakAuthenticatorValve.java:181) ~[spring-boot-container-bundle-10.0.2.jar:10.0.2]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) ~[na:na]
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) ~[na:na]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.39.jar:9.0.39]
    at java.base/java.lang.Thread.run(Thread.java:834) ~[na:na]

Where is my mistake? Thanks to everyone who replies to this post!

Answer 1

If you want to have Spring inject you the beans you have to either:

• Add @Autowired to the field
• Add @Autowired to a setter for the field
• Provide a constructor parameter (and optionally add @Autowired to the constructor)

In your case you are using Lombok with the @RequiredArgsConstructor which adds all final fields to the constructor but the field customerService is not final.

Here is the correct implementation of your REST controller:

@RestController
@RequiredArgsConstructor
@RequestMapping("/customers")
@Api(tags = "customers", value = "Customres")
public class CustomersController {
    private final CustomerService customerService;

    @GetMapping
    @ApiOperation(tags = "customers", value = "Get all")
    public Page<CustomerRsDto> getAll(Pageable pageable) {
        if (isNull(customerService)) {
            System.out.println("Not linked bean?");
        }
        return customerService.getAll(pageable);
    }
}

Another hint (not directly concerning this problem): use the findAll method with the Pageable parameter in your repository like this:

@Service
@RequiredArgsConstructor
public class CustomerServiceImpl implements CustomerService {
    private final CustomerRepository customerRepository;
    private final CustomerMapper customerMapper;

    @Override
    @Transactional
    public Page<CustomerRsDto> getAll(Pageable pageable) {
        Page<Customer> dbCustomers = customerRepository.findAll(pageable);
        return dbCustomers.map(dbCustomer -> customerMapper.toRsDto(dbCustomer));
    }
}