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在获取实际结果之前执行Spring Cache SpEL

分类：编程问答

如何解决在获取实际结果之前执行Spring Cache SpEL

我在@Cacheable批注中使用Spring SpEL来基于查询结果生成缓存键。似乎Spring尝试在执行实际的SQL查询并提取结果之前解析SpEL表达式。这是我的代码：

实体：

@Data
@Entity
@Table(name="users")
public class User  implements Serializable {
 
    private static final long serialVersionUID = 4671997077489607772L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    
    @Column(name="first_name")
    private String firstName;
    
    @Column(name="last_name")
    private String lastName;
    
    @Column(name="email")
    private String email;
    
    @Column(name="department_id")
    private Long department;
}

存储库：

@RepositoryRestResource(collectionResourceRel = "user",path = "user")
public interface UserRepository extends CrudRepository<User,Long> {

     @Cacheable(value = "testCache",key = "{#result.lastName,#result.firstName}")
     Optional<User> findById(Long id);
}

当我执行cURL请求curl -i http://localhost:8080/user/1

我正在例外：

org.springframework.expression.spel.SpelEvaluationException: EL1007E: Property or field 'lastName' cannot be found on null
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.readProperty(PropertyOrFieldReference.java:213) ~[spring-expression-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:104) ~[spring-expression-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.expression.spel.ast.PropertyOrFieldReference.access$000(PropertyOrFieldReference.java:51) ~[spring-expression-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.expression.spel.ast.PropertyOrFieldReference$AccessorLValue.getValue(PropertyOrFieldReference.java:406) ~[spring-expression-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:92) ~[spring-expression-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:112) ~[spring-expression-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.expression.spel.ast.InlineList.getValueInternal(InlineList.java:98) ~[spring-expression-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:112) ~[spring-expression-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:267) ~[spring-expression-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.cache.interceptor.CacheOperationExpressionEvaluator.key(CacheOperationExpressionEvaluator.java:104) ~[spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.cache.interceptor.CacheAspectSupport$CacheOperationContext.generateKey(CacheAspectSupport.java:778) ~[spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.cache.interceptor.CacheAspectSupport.generateKey(CacheAspectSupport.java:575) ~[spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.cache.interceptor.CacheAspectSupport.findCachedItem(CacheAspectSupport.java:518) ~[spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.cache.interceptor.CacheAspectSupport.execute(CacheAspectSupport.java:401) ~[spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.cache.interceptor.CacheAspectSupport.execute(CacheAspectSupport.java:345) ~[spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.cache.interceptor.CacheInterceptor.invoke(CacheInterceptor.java:61) ~[spring-context-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212) ~[spring-aop-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at com.sun.proxy.$Proxy107.findById(UnkNown Source) ~[na:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
    at org.springframework.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:279) ~[spring-core-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.data.repository.support.ReflectionRepositoryInvoker.invoke(ReflectionRepositoryInvoker.java:256) ~[spring-data-commons-2.2.1.RELEASE.jar:2.2.1.RELEASE]
    at org.springframework.data.repository.support.ReflectionRepositoryInvoker.invokeFindById(ReflectionRepositoryInvoker.java:145) ~[spring-data-commons-2.2.1.RELEASE.jar:2.2.1.RELEASE]
    at org.springframework.data.repository.support.CrudRepositoryInvoker.invokeFindById(CrudRepositoryInvoker.java:92) ~[spring-data-commons-2.2.1.RELEASE.jar:2.2.1.RELEASE]
    at org.springframework.data.rest.core.support.UnwrappingRepositoryInvokerFactory$UnwrappingRepositoryInvoker.invokeFindById(UnwrappingRepositoryInvokerFactory.java:94) ~[spring-data-rest-core-3.2.1.RELEASE.jar:3.2.1.RELEASE]
    at org.springframework.data.rest.webmvc.RepositoryEntityController.getItemResource(RepositoryEntityController.java:518) ~[spring-data-rest-webmvc-3.2.1.RELEASE.jar:3.2.1.RELEASE]
    at org.springframework.data.rest.webmvc.RepositoryEntityController.getItemResource(RepositoryEntityController.java:331) ~[spring-data-rest-webmvc-3.2.1.RELEASE.jar:3.2.1.RELEASE]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
    at org.springframework.web.method.support.invocableHandlerMethod.doInvoke(invocableHandlerMethod.java:190) ~[spring-web-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.method.support.invocableHandlerMethod.invokeForRequest(invocableHandlerMethod.java:138) ~[spring-web-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletinvocableHandlerMethod.invokeAndHandle(ServletinvocableHandlerMethod.java:106) ~[spring-webmvc-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:888) ~[spring-webmvc-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793) ~[spring-webmvc-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.servlet.dispatcherServlet.dodispatch(dispatcherServlet.java:1040) ~[spring-webmvc-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.servlet.dispatcherServlet.doService(dispatcherServlet.java:943) ~[spring-webmvc-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.1.RELEASE.jar:5.2.1.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:861) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1579) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at org.apache.tomcat.util.net.socketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_191]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_191]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.27.jar:9.0.27]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_191]

因此，似乎@Cacheable SpEL表达式在结果可用之前就已被求值。如果我通过添加非null条件来修改@Cacheable批注：

@Cacheable(value = "testCache",#result.firstName}",condition="#result != null")

我正在获得结果，但是显然没有任何缓存。我想知道这种行为是设计使然还是做错了什么？

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