[JPA] 양방향 매핑 순환참조 문제

오류

java.lang.IllegalStateException: Cannot call sendError() after the response has been committed
	at org.apache.catalina.connector.ResponseFacade.checkCommitted(ResponseFacade.java:504) ~[tomcat-embed-core-10.1.8.jar:10.1.8]
	at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:348) ~[tomcat-embed-core-10.1.8.jar:10.1.8]
	at jakarta.servlet.http.HttpServletResponseWrapper.sendError(HttpServletResponseWrapper.java:97) ~[tomcat-embed-core-10.1.8.jar:6.0]
	at jakarta.servlet.http.HttpServletResponseWrapper.sendError(HttpServletResponseWrapper.java:97) ~[tomcat-embed-core-10.1.8.jar:6.0]
	at jakarta.servlet.http.HttpServletResponseWrapper.sendError(HttpServletResponseWrapper.java:97) ~[tomcat-embed-core-10.1.8.jar:6.0]
	at org.springframework.security.web.util.OnCommittedResponseWrapper.sendError(OnCommittedResponseWrapper.java:116) ~[spring-security-web-6.0.3.jar:6.0.3]
	at org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.sendServerError(DefaultHandlerExceptionResolver.java:581) ~[spring-webmvc-6.0.8.jar:6.0.8]
	at org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.handleHttpMessageNotWritable(DefaultHandlerExceptionResolver.java:548) ~[spring-webmvc-6.0.8.jar:6.0.8]
	at org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver.doResolveException(DefaultHandlerExceptionResolver.java:221) ~[spring-webmvc-6.0.8.jar:6.0.8]
	at org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver.resolveException(AbstractHandlerExceptionResolver.java:141) ~[spring-webmvc-6.0.8.jar:6.0.8]
	at org.springframework.web.servlet.handler.HandlerExceptionResolverComposite.resolveException(HandlerExceptionResolverComposite.java:80) ~[spring-webmvc-6.0.8.jar:6.0.8]
	at org.springframework.web.servlet.DispatcherServlet.processHandlerException(DispatcherServlet.java:1341) ~[spring-webmvc-6.0.8.jar:6.0.8]
	at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1152) ~[spring-webmvc-6.0.8.jar:6.0.8]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1098) ~[spring-webmvc-6.0.8.jar:6.0.8]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:974) ~[spring-webmvc-6.0.8.jar:6.0.8]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1011) ~[spring-webmvc-6.0.8.jar:6.0.8]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:903) ~[spring-webmvc-6.0.8.jar:6.0.8]
	at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:564) ~[tomcat-embed-core-10.1.8.jar:6.0]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885) ~[spring-webmvc-6.0.8.jar:6.0.8]
    ..

java.lang.StackOverflowError: null
	at java.base/java.lang.ClassLoader.defineClass1(Native Method) ~[na:na]
	at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1013) ~[na:na]
	at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:862) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:760) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:681) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:639) ~[na:na]
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188) ~[na:na]
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521) ~[na:na]
	at com.fasterxml.jackson.databind.JsonMappingException.prependPath(JsonMappingException.java:455) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:792) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:733) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:774) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:145) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:107) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:733) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:774) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:733) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:774) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serializeContents(CollectionSerializer.java:145) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:107) ~[jackson-databind-2.14.2.jar:2.14.2]
	at com.fasterxml.jackson.databind.ser.std.CollectionSerializer.serialize(CollectionSerializer.java:25) ~[jackson-databind-2.14.2.jar:2.14.2]

 

원인

Spring JPA에서 두 객체가 ManyToOne, OneToMany 양방향 관계일 때, Judgement Entity를 조회하는 과정에서 순환참조 문제가 발생한다.

LAZY 로딩은 데이터베이스에서 Object를 가져올 때 맵핑 되어있는 다른 Object를 가져오지 않는 것이다.
Entity 객체를 그대로 JSON 문자열로 변환하는 과정에서 Judgement객체의 feedbacks 필드가 Feedback Entity를 참조하고, Feedback 객체의 judgement 필드가 Judgement Entity를 참조하며 순환참조 문제가 발생하는 것이다.

 

해결방법

@JsonIgnore 어노테이션이 달린 속성에 대해 직렬화 또는 역직렬화되지 않도록 무시하는 기능이 적용된다.
그렇게하면 더 이상 순환참조가 발생하지 않게된다.