No serializer found for class 에러, Errors 객체를 Serialization 할 때 발생하는 에러!
- 에러모음
- 2020. 7. 19. 13:57
안녕하세요.
이전 포스팅에서 커스텀 어노테이션으로 Bean Validation 처리를 해보는 예제를 작성하여 포스팅하였습니다.
https://sas-study.tistory.com/343
스프링 Custom Bean Validation 만들어서 사용해보기(어노테이션 @Email)
스프링 Bean Validation 이란?? 스프링에서는 JavaBean(getter와 setter를 가지고 있는 자바객체, 흔히 VO, DTO라고 부르는 것들)의 유효성 작업을 진행하기 위해 javax.validation 패키지 내에 있는 여러가지 유..
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그 와중에 response body에 에러메시지를 담는 과정에서 Errors 객체를 사용하여 DefaultMessage로 설정한 내용을 담아보내었습니다.
여기서 발견한 부분인데 그냥 개인적으로 Errors 객체를 그냥 넣어버리면 다른 내용을 참조하기도 하고 편할 것 같아서 Response Body에 errors 인스턴스를 그대로 던졌고 에러가 발생했습니다.
에러내용
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class org.springframework.validation.DefaultMessageCodesResolver]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class org.springframework.validation.DefaultMessageCodesResolver and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: org.springframework.validation.BeanPropertyBindingResult["messageCodesResolver"])
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
at org.springframework.test.web.servlet.TestDispatcherServlet.service(TestDispatcherServlet.java:72)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
at org.springframework.mock.web.MockFilterChain$ServletFilterProxy.doFilter(MockFilterChain.java:167)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.springframework.mock.web.MockFilterChain.doFilter(MockFilterChain.java:134)
at org.springframework.test.web.servlet.MockMvc.perform(MockMvc.java:183)
at com.example.demo1.UserControllerTests.addUser(UserControllerTests.java:32)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:686)
at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$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.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:212)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:208)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:137)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:71)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:135)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80)
at java.util.ArrayList.forEach(ArrayList.java:1257)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80)
at java.util.ArrayList.forEach(ArrayList.java:1257)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:248)
at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$5(DefaultLauncher.java:211)
at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:226)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:199)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:132)
at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:69)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
Caused by: org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class org.springframework.validation.DefaultMessageCodesResolver]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class org.springframework.validation.DefaultMessageCodesResolver and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: org.springframework.validation.BeanPropertyBindingResult["messageCodesResolver"])
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:323)
at org.springframework.http.converter.AbstractGenericHttpMessageConverter.write(AbstractGenericHttpMessageConverter.java:104)
at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodProcessor.writeWithMessageConverters(AbstractMessageConverterMethodProcessor.java:287)
at org.springframework.web.servlet.mvc.method.annotation.HttpEntityMethodProcessor.handleReturnValue(HttpEntityMethodProcessor.java:219)
at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:82)
at org.springframework.hateoas.server.mvc.RepresentationModelProcessorHandlerMethodReturnValueHandler.handleReturnValue(RepresentationModelProcessorHandlerMethodReturnValueHandler.java:101)
at org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:82)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:123)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
... 81 more
Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class org.springframework.validation.DefaultMessageCodesResolver and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: org.springframework.validation.BeanPropertyBindingResult["messageCodesResolver"])
at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:77)
at com.fasterxml.jackson.databind.SerializerProvider.reportBadDefinition(SerializerProvider.java:1277)
at com.fasterxml.jackson.databind.DatabindContext.reportBadDefinition(DatabindContext.java:400)
at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.failForEmpty(UnknownSerializer.java:71)
at com.fasterxml.jackson.databind.ser.impl.UnknownSerializer.serialize(UnknownSerializer.java:33)
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:728)
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:723)
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:166)
at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:480)
at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:319)
at com.fasterxml.jackson.databind.ObjectWriter$Prefetch.serialize(ObjectWriter.java:1513)
at com.fasterxml.jackson.databind.ObjectWriter.writeValue(ObjectWriter.java:1005)
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.writeInternal(AbstractJackson2HttpMessageConverter.java:317)
... 94 more- No serializer found for class ... : 특정 클래스에 대한 Serializer를 찾지 못하였습니다.
라는 내용의 에러메시지였고 저는 이 에러를 내는 AbstractJackson2HttpMessageConverter 클래스를 뜯어보았습니다.
그러다보니 생성자에 다음과 같은 의심이 가는 부분을 발견했습니다.
생성자는 ObjectMapper 객체를 argument로 받았고, 이는 jackson 라이브러리에서 관리하는 객체였기 때문입니다.
실제로 에러가 발생하는 위치는
에러발생 위치는 ObjectWriter를 사용하여 Response에 담길 내용을 serialize하는 작업이었고 이는 ObjectMapper를 사용하여 생성된 인스턴스였습니다.
스프링의 Bean 싱글톤 기반이기 때문에 ObjectMapper를 빈으로 등록하고 특정 Serializer 클래스를 따로 설정해주어 Errors 객체가 objectMapper에 의해 타입변환될 때 해당 Serializer를 이용해서 직렬화를 하도록 설정해주면 되겠다고 생각했습니다.
그래서 따로 ObjectMapper에 대한 설정과 ErrorsSerializer 클래스를 생성하여 Errors 객체용 Serializer 클래스를 생성해주었습니다.
ErrorsSerializer 클래스
package com.example.demo1;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;
import org.springframework.boot.jackson.JsonComponent;
import org.springframework.validation.Errors;
import java.io.IOException;
@JsonComponent
public class ErrorsSerializer extends JsonSerializer<Errors> {
@Override
public void serialize(Errors errors, JsonGenerator gen, SerializerProvider serializers)
throws IOException {
gen.writeStartArray();
errors.getFieldErrors().stream().forEach(e -> {
try {
gen.writeStartObject();
gen.writeStringField("field", e.getField());
gen.writeStringField("objectName", e.getObjectName());
gen.writeStringField("code", e.getCode());
gen.writeStringField("defaultMessage", e.getDefaultMessage());
Object rejectedValue = e.getRejectedValue();
if(rejectedValue != null) {
gen.writeStringField("rejectedValue", rejectedValue.toString());
}
gen.writeEndObject();
} catch(IOException e1) {
e1.printStackTrace();
}
});
errors.getGlobalErrors().forEach(e -> {
try {
gen.writeStartObject();
gen.writeStringField("objectName", e.getObjectName());
gen.writeStringField("code", e.getCode());
gen.writeStringField("defaultMessage", e.getDefaultMessage());
gen.writeEndObject();
} catch(IOException e1) {
e1.printStackTrace();
}
});
gen.writeEndArray();
}
}
- 해당 ErrorsSerializer 클래스의 소스는 Inflearn 사이트에서 백기선님의 REST-API 강의에서 공부한 내용입니다.
- Field Error와 Global Error에 대하여 발생한 에러의 내용을 배열에 담아서 response body에 직렬화될 내용을 정의하는 클래스입니다.
- 클래스 정의부에 JsonSerializer 클래스를 상속하고 제네릭 타입으로 Errors 객체를 넣어주면, 이 클래스는 Errors 전용 Serializer 클래스이고 Errors 타입의 인스턴스가 직렬화가 될때 호출되어 body에 담길 내용을 JsonGenerator 클래스에 정의된 내용으로 담습니다.
ObjectMapper 설정
package com.example.demo1;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
@SpringBootApplication
public class Demo1Application {
public static void main(String[] args) {
SpringApplication.run(Demo1Application.class, args);
}
@Bean
public ObjectMapper objectMapper() {
ObjectMapper objectMapper = new ObjectMapper();
//1.
/*
objectMapper = Jackson2ObjectMapperBuilder
.json()
.serializerByType(Errors.class, new ErrorsSerializer())
.build();
*/
//2.
//objectMapper.registerModule(new JsonModule());
//objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, true);
return objectMapper;
}
}
- Jacskon2ObjectMapperBuilder.json() -> new Jacskon2ObjectMapperBuilder() 해주는 역할입니다.
- 여기에 serailizerByType으로 Errors의 Class 타입과 해당 클래스의 Serializer인 ErrorsSerializer 클래스의 인스턴스를 던져줍니다.
- 이를 build() 하여 Bean으로 등록해두면 추후에 직렬화 작업을 할 때 Errors 인스턴스는 ErrorsSerailizer에 정의된 내용으로 직렬화하게됩니다.
ObjectMapper 설정2
두번째 방법은 정의한 모듈을 등록하여 그 안에 정의하는 방법입니다.
JsonModule이라는 클래스는 다음과 같습니다.
public class JsonModule extends SimpleModule {
public JsonModule() {
addSerializer(Errors.class, new ErrorsSerializer());
}
}여기서도 마찬가지로 SimpleModule 클래스를 상속하여 부모메소드인 addSerializer 클래스로 Errors 클래스타입과 ErrorsSerializer 인스턴스를 던져주면 그를 토대로 직렬화할 때 커스터마이징한 내용으로 에러내용을 담습니다.
이상 제가 접한 에러 메시지(No serializer found for class...)의 해결방법이었습니다.