英文:
Spring boot with JPA - Unable to return object from h2 database
问题
I'll provide the translated code and description of the issue you're facing:
你的数据被保存到了h2数据库中，但是当你尝试根据id获取person对象时，出现了错误，错误信息如下：
org.hibernate.TypeMismatchException: 提供的id类型与com.example.demo.Person类不匹配。期望类型：class java.lang.String，实际类型：class java.lang.Integer
问题出在这一行：Person person = personDBHandlerObj.findById(id).orElse(new Person());
根据错误信息，Hibernate期望传入String类型的id，但是你传入的是Integer类型的id。要解决这个问题，你需要确保传入的id与Person类中id的数据类型一致，或者对类型进行适当的转换。
英文:
I'm learning Spring boot and I tried implementing a simple save and fetch database web app.
This is my controller class :
package com.example.demo;
import java.util.Optional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;
@Controller
public class WebsiteClass
{
@Autowired
PersonDBHandler personDBHandlerObj;
@RequestMapping("index")
public String index()
{
return "home.jsp";
}
@RequestMapping("addPerson")
public String addObject(Person obj)
{
personDBHandlerObj.save(obj);
return "home.jsp";
}
@RequestMapping("getPerson")
public ModelAndView getObject(@RequestParam int id)
{
ModelAndView mv = new ModelAndView("showPerson.jsp");
Person person = personDBHandlerObj.findById(id).orElse(new Person());
mv.addObject(person);
return mv;
}
}
The data is getting saved into h2 database, but when I try to fetch the person object by id, I'm getting an error at line Person person = personDBHandlerObj.findById(id).orElse(new Person());. The error -
org.hibernate.TypeMismatchException: Provided id of the wrong type for class com.example.demo.Person. Expected: class java.lang.String, got class java.lang.Integer
at org.hibernate.event.internal.DefaultLoadEventListener.checkIdClass(DefaultLoadEventListener.java:155) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:71) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:113) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at org.hibernate.internal.SessionImpl.fireLoadNoChecks(SessionImpl.java:1187) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1176) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at org.hibernate.internal.SessionImpl.access$2100(SessionImpl.java:194) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.doLoad(SessionImpl.java:2787) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.lambda$load$1(SessionImpl.java:2768) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.perform(SessionImpl.java:2724) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.load(SessionImpl.java:2768) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at org.hibernate.internal.SessionImpl.find(SessionImpl.java:3323) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at org.hibernate.internal.SessionImpl.find(SessionImpl.java:3290) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:366) ~[spring-orm-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at com.sun.proxy.$Proxy76.find(Unknown Source) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:314) ~[spring-orm-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at com.sun.proxy.$Proxy76.find(Unknown Source) ~[na:na]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.findById(SimpleJpaRepository.java:281) ~[spring-data-jpa-2.3.3.RELEASE.jar:2.3.3.RELEASE]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.data.repository.core.support.ImplementationInvocationMetadata.invoke(ImplementationInvocationMetadata.java:72) ~[spring-data-commons-2.3.3.RELEASE.jar:2.3.3.RELEASE]
at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:382) ~[spring-data-commons-2.3.3.RELEASE.jar:2.3.3.RELEASE]
at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:205) ~[spring-data-commons-2.3.3.RELEASE.jar:2.3.3.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:549) ~[spring-data-commons-2.3.3.RELEASE.jar:2.3.3.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:155) ~[spring-data-commons-2.3.3.RELEASE.jar:2.3.3.RELEASE]
at org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:130) ~[spring-data-commons-2.3.3.RELEASE.jar:2.3.3.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:367) ~[spring-tx-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:118) ~[spring-tx-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:178) ~[spring-data-jpa-2.3.3.RELEASE.jar:2.3.3.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:95) ~[spring-aop-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at com.sun.proxy.$Proxy79.findById(Unknown Source) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344) ~[spring-aop-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:205) ~[spring-aop-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at com.sun.proxy.$Proxy58.findById(Unknown Source) ~[na:na]
at com.example.demo.WebsiteClass.getPerson(WebsiteClass.java:35) ~[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:564) ~[na:na]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:626) ~[tomcat-embed-core-9.0.37.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) ~[tomcat-embed-core-9.0.37.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.8.RELEASE.jar:5.2.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1589) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) ~[na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) ~[na:na]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.37.jar:9.0.37]
at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]
The JSP files contain the following forms.
home.jsp -
<body>
<form action="addPerson">
<input type="text" name="name">
<input type="number" name="id">
<input type="submit">
</form>
<br>
<form action="getPerson">
<input type="number" name="id">
<input type="submit">
</form>
</body>
showPerson.jsp -
<body>
${person}
</body>
</html>
EDIT : Added classes below
Person -
package com.example.demo;
import javax.persistence.Id;
import org.hibernate.annotations.Entity;
import org.springframework.stereotype.Component;
@javax.persistence.Entity
public class Person
{
@Id
private String name;
private int id;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
/*@Override
public String toString()
{
return "Person - "+name+", ID - "+id;
}*/
}
PersonDBHandler -
package com.example.demo;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Component;
public interface PersonDBHandler extends CrudRepository<Person, Integer>
{
}
What am I doing wrong?
答案1
得分: 3
正如错误消息所说，
> org.hibernate.TypeMismatchException：为 com.example.demo.Person 类提供了错误类型的 id。预期：class java.lang.String，实际得到：class java.lang.Integer
你应该传递一个字符串类型的 id，而不是整数类型的 id。尝试将你的代码更改为：
@RequestMapping("getPerson")
public ModelAndView getObject(@RequestParam String id)
{
ModelAndView mv = new ModelAndView("showPerson.jsp");
Person person = personDBHandlerObj.findById(id).orElse(new Person());
mv.addObject(person);
return mv;
}
如果这样仍然不起作用，你可能需要在这里分享你的 Person 类定义和 personDBHandlerObj。
编辑：
既然你分享了你代码的其余部分，我们看到问题出现在 Person 类中。
@Id
private String name;
@Id 注解将 name 定义为 id，它的类型是字符串。id 字段实际包含什么内容并不重要。
要么（a）在 id 上方加上 @Id 注解（如果你有一个 id 字段，实际上不需要这个注解），要么（b）使用 name 作为 id，然后使用 name 进行查询，而不是整数。
我还建议你阅读 https://www.baeldung.com/hibernate-identifiers。
英文:
As the error message says
> org.hibernate.TypeMismatchException: Provided id of the wrong type for class com.example.demo.Person. Expected: class java.lang.String, got class java.lang.Integer
you should pass a string id instead of an integer one.
Try changing your code to
@RequestMapping("getPerson")
public ModelAndView getObject(@RequestParam String id)
{
ModelAndView mv = new ModelAndView("showPerson.jsp");
Person person = personDBHandlerObj.findById(id).orElse(new Person());
mv.addObject(person);
return mv;
}
If this does not work, you will want to share your Person class definition and your personDBHandlerObj here.
EDIT:
Now that you shared the rest of your code, we see that the issue lies in the Person class.
@Id
private String name;
The @Id annotation defines the name as the id - which is of type string. It does not matter what the id field holds.
Either (a) annotate @Id above id ( I think if you have an id field, you do not actually need the annotation) or (b) use the name as id and then query using the name and not an integer.
Also I recommend you to read https://www.baeldung.com/hibernate-identifiers
答案2
得分: 2
Sure, here's the translation:
你能否也按照这样的方式添加表名：
@Entity
@Table(name = "person")
public class Person...
你能将你的代码修改为以下内容吗：
@Id
@Column(name = "id")
private int id;
在你的数据库中，id 字段的类型也是 int 吗？
英文:
Can you please also add the table name like this:
@Entity
@Table(name = "person")
public class Person...
Can you change your code to this:
@Id
@Column(name = "id")
private int id;
Is id of type int in your database too?
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论