Projections.fields 관련 질문입니다.

Question

Projections을 이용한 조회 테스트를 하고 있던중 Projections.fields에 대해 궁금한점이 있습니다.   Dto에 @AllArgsConstructor만 적용하고 Projections.fields를 사용하게 되면 해당 인스턴스를 만들지 못한다고 exception이 발생합니다. 영한님께서 강의에서 말쓴하신 Projections.fields의 특성은 getter, setter가 필요가 없고 생성자 또한 필요가 없다라고 하셨는데 이상하게 @AllArgsConstructor를 추가하면 exception이 발생합니다. ex @Getter @AllArgsConstructor public class ArticleFieldsDto{ private Long id; private String title; private LocalDateTime lastModifiedDate; private Long lastModifiedBy; }   예외 로그 com.querydsl.core.types.ExpressionException: com.mylaboratory.jpa_and_querydsl.projections.dto.ArticleFieldsDto at com.querydsl.core.types.QBean.newInstance(QBean.java:246) at com.querydsl.core.support.NumberConversions.newInstance(NumberConversions.java:86) at com.querydsl.jpa.FactoryExpressionTransformer.transformTuple(FactoryExpressionTransformer.java:51) at org.hibernate.sql.results.internal.RowTransformerTupleTransformerAdapter.transformRow(RowTransformerTupleTransformerAdapter.java:30) at org.hibernate.sql.results.internal.StandardRowReader.readRow(StandardRowReader.java:109) at org.hibernate.sql.results.spi.ListResultsConsumer.consume(ListResultsConsumer.java:198) at org.hibernate.sql.results.spi.ListResultsConsumer.consume(ListResultsConsumer.java:33) at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.doExecuteQuery(JdbcSelectExecutorStandardImpl.java:443) at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.executeQuery(JdbcSelectExecutorStandardImpl.java:166) at org.hibernate.sql.exec.internal.JdbcSelectExecutorStandardImpl.list(JdbcSelectExecutorStandardImpl.java:91) at org.hibernate.sql.exec.spi.JdbcSelectExecutor.list(JdbcSelectExecutor.java:31) at org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.lambda$new$0(ConcreteSqmSelectQueryPlan.java:113) at org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.withCacheableSqmInterpretation(ConcreteSqmSelectQueryPlan.java:335) at org.hibernate.query.sqm.internal.ConcreteSqmSelectQueryPlan.performList(ConcreteSqmSelectQueryPlan.java:276) at org.hibernate.query.sqm.internal.QuerySqmImpl.doList(QuerySqmImpl.java:571) at org.hibernate.query.spi.AbstractSelectionQuery.list(AbstractSelectionQuery.java:363) at org.hibernate.query.sqm.internal.QuerySqmImpl.list(QuerySqmImpl.java:1073) at org.hibernate.query.spi.AbstractSelectionQuery.getSingleResult(AbstractSelectionQuery.java:457) at org.hibernate.query.sqm.internal.QuerySqmImpl.getSingleResult(QuerySqmImpl.java:1103) at com.querydsl.jpa.impl.AbstractJPAQuery.getSingleResult(AbstractJPAQuery.java:214) at com.querydsl.jpa.impl.AbstractJPAQuery.fetchOne(AbstractJPAQuery.java:326) at com.mylaboratory.jpa_and_querydsl.projections.ProjectionsTest.projections_field(ProjectionsTest.java:70) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:568) at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:727) at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60) at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131) at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:156) at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:147) at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:86) at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(InterceptingExecutableInvoker.java:103) at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.lambda$invoke$0(InterceptingExecutableInvoker.java:93) at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106) at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64) at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45) at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37) at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.invoke(InterceptingExecutableInvoker.java:92) at org.junit.jupiter.engine.execution.InterceptingExecutableInvoker.invoke(InterceptingExecutableInvoker.java:86) at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:217) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:213) at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:138) at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:68) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141) at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138) at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95) at java.base/java.util.ArrayList.forEach(ArrayList.java:1511) at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141) at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138) at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95) at java.base/java.util.ArrayList.forEach(ArrayList.java:1511) at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141) at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138) at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95) at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35) at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57) at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54) at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:147) at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:127) at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:90) at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:55) at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:102) at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:54) at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114) at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86) at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86) at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53) at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71) at com.intellij.rt.junit.IdeaTestRunner$Repeater$1.execute(IdeaTestRunner.java:38) at com.intellij.rt.execution.junit.TestsRepeater.repeat(TestsRepeater.java:11) at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:35) at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235) at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54) Caused by: java.lang.InstantiationException: com.mylaboratory.jpa_and_querydsl.projections.dto.ArticleFieldsDto at java.base/java.lang.Class.newInstance(Class.java:639) at com.querydsl.core.types.QBean.create(QBean.java:251) at com.querydsl.core.types.QBean.newInstance(QBean.java:222) ... 91 more Caused by: java.lang.NoSuchMethodException: com.mylaboratory.jpa_and_querydsl.projections.dto.ArticleFieldsDto.<init>() at java.base/java.lang.Class.getConstructor0(Class.java:3585) at java.base/java.lang.Class.newInstance(Class.java:626) ... 93 more   예외가 발생하지 않는 경우는 아래와 같습니다. @NoArgsConstructor, @AllArgsConstructor 모두 사용 @NoArgsConstructor, @AllArgsConstructor 모두 사용 X @NoArgsConstructor 만 사용

나무늘보 · Answer

안녕하세요, 조윤호 님. 공식 서포터즈 y2gcoder 입니다. 본 강의 6:21초를 참조하시면 기본 생성자가 필요하다고 설명하시는 부분이 나옵니다 :) 프로젝션으로 사용하는 DTO에는 기본 생성자를 추가해 주세요 감사합니다.