Spring 5 In Action - Spring MVC Form Submit object always null where as the post method arguments are showing values

Question

It's from Spring in Action ch03 JDBC The taco object is always null. Taco saved = designRepo.save(taco) throws null pointer exception --updated as below, thanks JB Nizet -- It's from Spring in Action ch03 JDBC designRepo is null Taco saved = designRepo.save(taco) throws null pointer exception Unable to figure out where jdbc (in JdbcTacoRepository) is instantiated

Controller

@PostMapping
  public String processDesign(
          @Valid @ModelAttribute("taco") Taco taco, Errors errors, 
      @ModelAttribute Order order) {

    if (errors.hasErrors()) {
      return "design";
    }

    log.info("post: ", taco.toString());

    //the below line throws null pointer exception, hence commented
    //Taco saved = designRepo.save(taco);
    //order.addDesign(saved);

    return "redirect:/orders/current";
  }

Converter

@Component
public class IngredientByIdConverter implements Converter<String, Ingredient> {

  private IngredientRepository ingredientRepo;

  @Autowired
  public IngredientByIdConverter(IngredientRepository ingredientRepo) {
    this.ingredientRepo = ingredientRepo;
  }

  @Override
  public Ingredient convert(String id) {
    return ingredientRepo.findOne(id);
  }

}

JdbcTacoRepository

@Repository
public class JdbcTacoRepository implements TacoRepository {

  private JdbcTemplate jdbc;

  @Autowired
  public JdbcTacoRepository(JdbcTemplate jdbc) {
    this.jdbc = jdbc;
  }

  @Override
  public Taco save(Taco taco) {
    long tacoId = saveTacoInfo(taco);
    taco.setId(tacoId);
    for (Ingredient ingredient : taco.getIngredients()) {
      saveIngredientToTaco(ingredient, tacoId);
    }

    return taco;
  }

  private long saveTacoInfo(Taco taco) {
    taco.setCreatedAt(new Date());
    PreparedStatementCreator psc =
        new PreparedStatementCreatorFactory(
            "insert into Taco (name, createdAt) values (?, ?)",
            Types.VARCHAR, Types.TIMESTAMP
        ).newPreparedStatementCreator(
            Arrays.asList(
                taco.getName(),
                new Timestamp(taco.getCreatedAt().getTime())));

    KeyHolder keyHolder = new GeneratedKeyHolder();
    jdbc.update(psc, keyHolder);

    return keyHolder.getKey().longValue();
  }

  private void saveIngredientToTaco(
          Ingredient ingredient, long tacoId) {
    jdbc.update(
        "insert into Taco_Ingredients (taco, ingredient) " +
        "values (?, ?)",
        tacoId, ingredient.getId());
  }

}

Log

2019-12-22 01:34:48.717 TRACE 59846 --- [http-nio-8080-exec-4] .w.s.m.m.a.ServletInvocableHandlerMethod : Arguments: [Taco [name=TacoName1122, ingredients=[Ingredient [id=COTO, name=Corn Tortilla, type=WRAP], Ingredient [id=CARN, name=Carnitas, type=PROTEIN]], id=null, createdAt=null], org.springframework.validation.BeanPropertyBindingResult: 0 errors, com.mani.tacos.model.Order@14de87fe]
2019-12-22 01:34:48.718  INFO 59846 --- [http-nio-8080-exec-4] c.m.tacos.controller.DesignController    : post: Taco [name=TacoName1122, ingredients=[Ingredient [id=COTO, name=Corn Tortilla, type=WRAP], Ingredient [id=CARN, name=Carnitas, type=PROTEIN]], id=null, createdAt=null]
2019-12-22 01:34:48.726 TRACE 59846 --- [http-nio-8080-exec-4] o.s.web.servlet.DispatcherServlet        : Failed to complete request
Sun Dec 22 01:34:48 SGT 2019
    There was an unexpected error (type=Internal Server Error, status=500).
    No message available
    java.lang.NullPointerException
        at com.mani.tacos.repository.JdbcTacoRepository.saveTacoInfo(JdbcTacoRepository.java:54)
        at com.mani.tacos.repository.JdbcTacoRepository.save(JdbcTacoRepository.java:31)
        at com.mani.tacos.repository.JdbcTacoRepository$$FastClassBySpringCGLIB$$9c06a39c.invoke(<generated>)
        at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
        at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:769)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
        at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747)
        at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
        at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:747)
        at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689)
        at com.mani.tacos.repository.JdbcTacoRepository$$EnhancerBySpringCGLIB$$8e0297b.save(<generated>)
        at com.mani.tacos.controller.DesignController.processDesign(DesignController.java:92)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:888)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
        at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367)
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1591)
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.base/java.lang.Thread.run(Thread.java:834)

POM

<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>

properties

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.h2.console.enabled=true

Replace `log.info("post: ", taco.toString());` by `log.info("post: " + taco);`. Or, if you're using Slf4J, by `log.info("post: {}", taco);`. Voting to close for typo. — JB Nizet, Dec 21 '19 at 17:15
It's not the log.info problem. The taco object is null. When I try the next line Taco saved = designRepo.save(taco); I get null pointer which means taco is null — michael, Dec 21 '19 at 17:20
No. It probably means designRepo is null. Do as I told you, post the new logs, post the relevant code, post the stack trace of the exception. — JB Nizet, Dec 21 '19 at 17:21
You didn't fiw the log statement, which doesn't help knowing what the value of taco is. What's the line 54 of JdbcTacoRepository.java? — JB Nizet, Dec 21 '19 at 17:48
Line 54: return keyHolder.getKey().longValue(); Updated the log. Shouldn't somwhere I need to define what jdbc is? — michael, Dec 21 '19 at 17:50
So taco is not null, otherwise you would have the exception sooner. keyHolder can't be null since you initialized it just before. So keyHolder.getKey() is null. You haven't called https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/jdbc/core/PreparedStatementCreatorFactory.html#setReturnGeneratedKeys-boolean-, so that's most probably the reason. — JB Nizet, Dec 21 '19 at 17:55
@JBNizet Thanks a lot. I've been stuck at this for past 3-4 days. I also learnt how to read log and figure out where the actual error is — michael, Dec 21 '19 at 18:12
We meet this problem too. I think this question can help us. https://stackoverflow.com/questions/53655693/keyholder-getkey-return-null — xiahaoyun, May 24 '20 at 11:19

Spring 5 In Action - Spring MVC Form Submit object always null where as the post method arguments are showing values

0 Answers0