【发布时间】：2019-08-14 10:32:22
【问题描述】：
我正在尝试建立一个类似 Stack Overflow 的问答网站，以了解 RESTful Web 服务的工作原理，这是我第一次编写 Web 服务，我已经制作了用于提问和回答问题的控制器。
但是有一个问题，我在为 upvote 制作 REST Endpoint 时遇到了这个问题，所以每当用户提出问题时，我都必须更新问题表中的投票数（在开始时为零）但是当我尝试点击 Endpoint for Upvote 时，我编写的更新查询会引发错误并显示错误页面。
抛出的错误：
org.postgresql.util.PSQLException: No results were returned by the query.
at org.postgresql.jdbc.PgPreparedStatement.executeQuery(PgPreparedStatement.java:107) ~[postgresql-42.2.5.jar:42.2.5]
at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeQuery(ProxyPreparedStatement.java:52) ~[HikariCP-3.2.0.jar:na]
at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeQuery(HikariProxyPreparedStatement.java) ~[HikariCP-3.2.0.jar:na]
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:60) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.loader.Loader.getResultSet(Loader.java:2167) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1930) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.loader.Loader.executeQueryStatement(Loader.java:1892) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.loader.Loader.doQuery(Loader.java:937) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:340) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.loader.Loader.doList(Loader.java:2689) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.loader.Loader.doList(Loader.java:2672) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2506) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.loader.Loader.list(Loader.java:2501) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:338) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.internal.SessionImpl.listCustomQuery(SessionImpl.java:2223) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.internal.AbstractSharedSessionContract.list(AbstractSharedSessionContract.java:1069) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.query.internal.NativeQueryImpl.doList(NativeQueryImpl.java:170) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1505) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.hibernate.query.internal.AbstractProducedQuery.getSingleResult(AbstractProducedQuery.java:1553) ~[hibernate-core-5.3.10.Final.jar:5.3.10.Final]
at org.springframework.data.jpa.repository.query.JpaQueryExecution$SingleEntityExecution.doExecute(JpaQueryExecution.java:221) ~[spring-data-jpa-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:91) ~[spring-data-jpa-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:136) ~[spring-data-jpa-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:125) ~[spring-data-jpa-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:605) ~[spring-data-commons-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$invoke$3(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:595) ~[spring-data-commons-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:59) ~[spring-data-commons-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:295) ~[spring-tx-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98) ~[spring-tx-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:138) ~[spring-data-jpa-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93) ~[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61) ~[spring-data-commons-2.1.9.RELEASE.jar:2.1.9.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at com.sun.proxy.$Proxy100.vote(Unknown Source) ~[na:na]
at com.demo.beans.controller.QuestionController.upvoteQuestion(QuestionController.java:222) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_91]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_91]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_91]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_91]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:892) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1039) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:908) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:660) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) ~[spring-webmvc-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.21.jar:9.0.21]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.springframework.session.web.http.SessionRepositoryFilter.doFilterInternal(SessionRepositoryFilter.java:151) ~[spring-session-core-2.1.7.RELEASE.jar:2.1.7.RELEASE]
at org.springframework.session.web.http.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:85) ~[spring-session-core-2.1.7.RELEASE.jar:2.1.7.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:109) ~[spring-web-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) [tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:853) [tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1587) [tomcat-embed-core-9.0.21.jar:9.0.21]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.21.jar:9.0.21]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_91]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_91]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.21.jar:9.0.21]
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_91]
用于更新投票的 QuestionRepository 代码：
package com.demo.beans.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;
import com.demo.beans.Question;
@Repository
public interface QuestionRepository extends JpaRepository<Question, Long> {
@Query(value = "SELECT * from questions where pr_key=:pr_key", nativeQuery = true)
public Question findByPrKey(@Param("pr_key") String prKey);
@Query(value = "UPDATE questions SET questionvotes=:questionvotes where pr_key=:pr_key", nativeQuery=true)
public void changeVotes(@Param("questionvotes") int questionVotes, @Param("pr_key") String prKey);
}
这里第二个查询负责更新投票。
我在 QuestionsController 中用这个方法调用这个函数：
@RequestMapping("/upvoteQuestion")
public String upvoteQuestion(@CookieValue(value = "username", defaultValue = "null") String username,
@CookieValue(value = "password", defaultValue = "null") String password, @Valid QuestionVote questionVote) {
System.out.println("works" + questionVote.getQuestionPrKey() + " " + questionVote.getUserPrKey());
if (!username.equals("null") && !password.equals("null")) {
// checks whether there is user with the username and password given
// by the cookie
if (userRepository.checkWhetherAccountExists(username, password).get(0) != null) {
questionVote.setUserPrKey(userRepository.findUsingUsername(username).getPrKey());
if (questionVoteRepository.checkUpvote(questionVote.getQuestionPrKey(), questionVote.getUserPrKey()).equals("false")) {
questionVoteRepository.vote("true", "false", questionVote.getQuestionPrKey(),questionVote.getUserPrKey());
System.out.println("Question PrKey: " + questionVote.getQuestionPrKey());
questionRepository.changeVotes(13, questionVote.getQuestionPrKey());
}
}
}
return "redirect:/questions/"+questionVote.getQuestionPrKey();
}
在上面的代码中，下面一行抛出了错误：
questionRepository.changeVotes(13, questionVote.getQuestionPrKey());
我的问题类如下所示：
package com.demo.beans;
import java.sql.Time;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;
@Entity
@Table(name = "questions")
public class Question {
@Id
@GeneratedValue(generator = "uuid")
@GenericGenerator(name = "uuid", strategy = "uuid2")
@Column(name = "PR_KEY")
private String prKey;
@Column(name = "postedby")
private String postedBy; // pr_key of the person who posted the question
@Column(name = "postedbyusername")
private String postedByUsername; // username of the person who posted the
// question
@Column(name = "title", columnDefinition = "varchar(1000)")
private String title; // title of the question
@Column(name = "content", columnDefinition = "varchar(10000)")
private String content; // content of the question
@Column(name = "code", columnDefinition = "varchar(10000)")
private String code; // code (if included) of the question
@Column(name = "viewscount")
private int views_count; // views count of the question
@Column(name = "answercount")
private int answer_count; // answers count of the question
@Column(name = "tag")
private String tag; // tag which a question is tagged
@Column(name = "questionaskedtime")
private String questionAskedTime; // time at which the question was asked
@Column(name = "questionlastactivetime")
private String questionLastActiveTime; // time at which the question was
// active the last time
@Column(name = "questionvotes")
private int questionVotes; // number of votes on the question
@Column(name = "acceptedanswerstatus")
private String acceptedAnswerStatus; // whether the question has an accepted
// answer
@Column(name = "questionlink")
private String questionLink;
public Question() {
}
public Question(String postedBy, String title, String content, String code, int views_count, int answer_count,
String tag, String questionAskedTime, String questionLastActiveTime, int questionVotes,
String acceptedAnswerStatus, String questionLink, String postedByUsername) {
super();
this.title = title;
this.content = content;
this.code = code;
this.views_count = views_count;
this.answer_count = answer_count;
this.tag = tag;
this.questionAskedTime = questionAskedTime;
this.questionLastActiveTime = questionLastActiveTime;
this.questionVotes = questionVotes;
this.acceptedAnswerStatus = acceptedAnswerStatus;
this.questionLink = questionLink;
this.postedByUsername = postedByUsername;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public int getViews_count() {
return views_count;
}
public void setViews_count(int views_count) {
this.views_count = views_count;
}
public int getAnswer_count() {
return answer_count;
}
public void setAnswer_count(int answer_count) {
this.answer_count = answer_count;
}
public String getTags() {
return tag;
}
public void setTag(String tag) {
this.tag = tag;
}
public String getQuestionAskedTime() {
return questionAskedTime;
}
public void setQuestionAskedTime(String questionAskedTime) {
this.questionAskedTime = questionAskedTime;
}
public String getQuestionLastActiveTime() {
return questionLastActiveTime;
}
public void setQuestionLastActiveTime(String questionLastActiveTime) {
this.questionLastActiveTime = questionLastActiveTime;
}
public int getQuestionVotes() {
return questionVotes;
}
public void setQuestionVotes(int questionVotes) {
this.questionVotes = questionVotes;
}
public String getAcceptedAnswerStatus() {
return acceptedAnswerStatus;
}
public void setAcceptedAnserStatus(String acceptedAnswerStatus) {
this.acceptedAnswerStatus = acceptedAnswerStatus;
}
public String getPrKey() {
return prKey;
}
public void setPrKey(String prKey) {
this.prKey = prKey;
}
public String getPostedByUsername() {
return postedByUsername;
}
public void setPostedByUsername(String postedByUsername) {
this.postedByUsername = postedByUsername;
}
public String getQuestionLink() {
return questionLink;
}
public void setQuestionLink(String questionLink) {
this.questionLink = questionLink;
}
}
是的，我在表格中有数据。我做错了什么，我该如何解决？
我也尝试过添加@Modifying，但仍然抛出同样的错误。
编辑
我使用 UPDATE Query 更新了不同表中的其他字段，它可以工作，不知道为什么这不起作用。
questionVoteRepository.vote("true", "false", questionVote.getQuestionPrKey(),questionVote.getUserPrKey());
在上面添加的方法 upvoteQuestion 中检查上面的代码行，这行代码完美，更新了 question_votes 表。
QuestionVote POJO 如下所示：
package com.demo.beans;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import org.hibernate.annotations.GenericGenerator;
@Entity
@Table(name="question_votes")
public class QuestionVote {
@Id
@GeneratedValue(generator = "uuid")
@GenericGenerator(name = "uuid", strategy = "uuid2")
@Column(name = "PR_KEY")
private String prKey;
@Column(name="question_pr_key")
private String questionPrKey;
@Column(name="user_pr_key")
private String userPrKey;
@Column(name="upvote")
private String upvote;
@Column(name="downvote")
private String downvote;
public QuestionVote() {
}
public QuestionVote(String prKey, String questionPrKey, String userPrKey, String upvote, String downvote) {
super();
this.prKey = prKey;
this.questionPrKey = questionPrKey;
this.userPrKey = userPrKey;
this.upvote = upvote;
this.downvote = downvote;
}
public String getPrKey() {
return prKey;
}
public void setPrKey(String prKey) {
this.prKey = prKey;
}
public String getQuestionPrKey() {
return questionPrKey;
}
public void setQuestionPrKey(String questionPrKey) {
this.questionPrKey = questionPrKey;
}
public String getUserPrKey() {
return userPrKey;
}
public void setUserPrKey(String userPrKey) {
this.userPrKey = userPrKey;
}
public String getUpvote() {
return upvote;
}
public void setUpvote(String upvote) {
this.upvote = upvote;
}
public String getDownvote() {
return downvote;
}
public void setDownvote(String downvote) {
this.downvote = downvote;
}
}
添加问题后，我也在 question_votes 表中添加一行，并将该行的 upvote 和 downvote 列设置为 false、false。当问题被投票时，我更新了questions 和question_votes 这两个表，question_votes 表更新成功，但 questions 表没有更新。
QuestionVoteRepository 如下所示：
package com.demo.beans.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;
import com.demo.beans.QuestionVote;
@Repository
public interface QuestionVoteRepository extends JpaRepository<QuestionVote, Long>{
@Query(value = "SELECT exists (SELECT 1 from question_votes where question_pr_key=:question_pr_key and user_pr_key=:user_pr_key)", nativeQuery=true)
public String checkWhetherRowExists(@Param("question_pr_key") String questionPrKey,
@Param("user_pr_key") String userPrKey);
@Query(value = "SELECT upvote from question_votes where question_pr_key=:question_pr_key and user_pr_key=:user_pr_key", nativeQuery=true)
public String checkUpvote(@Param("question_pr_key") String questionPrKey, @Param("user_pr_key") String userPrKey);
@Query(value = "SELECT downvote from question_votes where question_pr_key=:question_pr_key and user_pr_key=:user_pr_key", nativeQuery=true)
public String checkDownvote(@Param("question_pr_key") String questionPrKey, @Param("user_pr_key") String userPrKey);
@Query(value = "UPDATE question_votes SET upvote=:upvote, downvote=:downvote where question_pr_key=:question_pr_key and user_pr_key=:user_pr_key", nativeQuery=true)
public void vote(@Param("upvote") String upvote, @Param("downvote") String downvote,
@Param("question_pr_key") String questionPrKey, @Param("user_pr_key") String userPrKey);
}
【问题讨论】：
-
尝试使用
PgPreparedStatement.execute()而不是executeQuery()，因为UPDATE不是查询，它是更新语句，不会返回任何行。 -
@deHaar 我在同一代码中使用了 UPDATE 语句来更新不同表中的其他字段，它工作正常，唯一的区别是在那个表中我正在更新一个字符串，但它是int，我不明白为什么这不起作用。
-
那么请在您的问题中编辑两个示例：一个不起作用，一个起作用。我们需要看看两者的数据访问代码。
-
好的，谢谢，但我看不到任何对
PgPreparedStatement.executeQuery()的呼叫。你只有带注释的方法吗？后面是什么？如果您尚未对数据库访问进行编码，则可能必须使用不同的注释或其他注释。 -
看起来您必须在 @AhmedAbdelhady 回答时添加
@Modifying注释。您也可以添加@Transactional，但我真的不知道这是否会改变任何事情。我认为@Modifying将在内部使用PgPreparedStatement的正确方法。
标签： java spring postgresql hibernate spring-boot