React - Axios get request returns data as NULL

Question

I am trying to make a get request from my back-end spring project. When I use the call I get a Null pointer exception for some reason. path seems to be fine and when I unit test on console It returns the correct value, however, while calling via axios get I get this error on my consol.

ERROR:

trace: "java.lang.NullPointerException\r\n\tat com.golden.scent.controllers.AdminController.getOnePerfume(AdminController.java:100)\r\n\tat java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)\r\n\tat java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\r\n\tat java.base/java.lang.reflect.Method.invoke(Method.java:566)\r\n\tat org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)\r\n\tat org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)\r\n\tat org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)\r\n\tat org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)\r\n\tat org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067)\r\n\tat org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963)\r\n\tat org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)\r\n\tat org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)\r\n\tat javax.servlet.http.HttpServlet.service(HttpServlet.java:655)\r\n\tat org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)\r\n\tat javax.servlet.http.HttpServlet.service(HttpServlet.java:764)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)\r\n\tat org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)\r\n\tat org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)\r\n\tat org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)\r\n\tat org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)\r\n\tat com.golden.scent.filers.CORSFilter.doFilter(CORSFilter.java:41)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)\r\n\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)\r\n\tat org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197)\r\n\tat org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)\r\n\tat org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540)\r\n\tat org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135)\r\n\tat org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)\r\n\tat org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)\r\n\tat org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)\r\n\tat org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382)\r\n\tat org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)\r\n\tat org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895)\r\n\tat org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1722)\r\n\tat org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)\r\n\tat org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)\r\n\tat org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)\r\n\tat org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)\r\n\tat java.base/java.lang.Thread.run(Thread.java:829)\r\n"

Back-end service:

  @Override
    public Perfume getOnePerfume(int id) throws DoesNotExistException {
        return perfumeRepository.findById(id).orElseThrow(()-> new DoesNotExistException(id));
    }

Controller:

  @GetMapping("/perfume/{id}")
    @ResponseStatus(HttpStatus.OK)
        public Perfume getOnePerfume(@PathVariable int id) throws DoesNotExistException {
        return admin.getOnePerfume(id);

        }

so basically on my front-end I have a CARD component with a Button using NavLink to navigate to a different component. I pass an id parameter on the route and use that param to fetch it on a different component.

CARD COMPONENT

 {
                            state.map(c => (
                                <Grid  item xs={4} sm={2} >
                                    <PerfumeCard key={c.id} perfume={c} />
                                    <button className="myButton2">  <NavLink
                                        style={{ textDecoration: "none" }}
                                        to={{
                                            pathname: '/home/myperfume/' + c.id,
                                          
                                            
                                            }}>
                                        Click here for details
                                    </NavLink></button>
                                </Grid>
                            ))
                        }

As you can see path is '/home/myperfume/' + c.id, which takes an ID prop to the URL as a parameter. so far so good.

Card Detail Component:

function MyPerfume(): JSX.Element {

    const [state, setState] = useState<any>('');
    const params = useParams()

    async function send() {
        let response = null;

        try {

            const id = params.id;
            console.log(id);
          
            response = await axios.get<PerfumeModel>("http://localhost:8080/admin/perfume/" + id);
            console.log(response.data);
            setState(response.data);
            store.dispatch(onePerfumesAction(response.data)); 
            console.log(response)

        } catch (err) {
            alert(err)

        }
    }

    useEffect(() => {
        send();
    });
    return (
        <div className="MyPerfume">

        </div>
    );
}

export default MyPerfume;

on this component I have the issue. I use useParams() to save id in a const. Now I am trying to fetch from back-end the data of the specific item by the ID, however, while trying to do this get request I get null pointer exception and I do not know why since the path seems correct.

Routing:

<Route path="/home/myperfume/:id" element={<MyPerfume/>}  />

NOTE: Using typescript Using React Router v6

Am I missing something over here?

Thanks for the help.

Answer 1

Possibly, the reason of strange behavior is the missing dependency array in useEffect , without dependency array, side-effect function runs every component render.