Difficulty in deserializating list of object-CodePudding

I am trying to make a rest call to bankingClient application's getTrans() method from AccountClient application, output returned will be List of Banking so in bankingClient app I made a BankingList pojo containing a field List of Banking and I am passing it to response type in rest template getForObject method but it is giving me error "Cannot deserialize value of type com.p1.pojo.BankingList from Array value"

This is the method in AccountClient which is making a call to BankingClient's "/banking/{ano}" mapping

@GetMapping("/listofTrans/{cid}")
public BankingList getTrans(@PathVariable Integer cid) {
    List<Account> a = acc.getByCid(cid);
    BankingList b=new BankingList();
    for(Account a1:a) {
        b = restTemplate.getForObject("http://BankingClient/banking/" a1.getAno(),BankingList.class);
    }
    return b;
}

This is the method in Banking Client

@GetMapping("/{ano}")
public List<Banking> getTrans(@PathVariable Integer ano) {
    return service.getTrans(ano);
}

This is my Banking class with getters,setters and constructors

public class Banking {
    private int trn_no;
    private String dateOfTrn;
    private int ano;
    private double amount;
}

and BankingList class

public class BankingList {
    public List<Banking> list
    public List<Banking> getList() {
        return list;
    }
    public void setList(List<Banking> list) {
        this.list = list;
    }   
}

and the error I am getting is as follows


com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `com.p1.pojo.BankingList` from Array value (token `JsonToken.START_ARRAY`)
 at [Source: (PushbackInputStream); line: 1, column: 1]
    at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59) ~[jackson-databind-2.12.5.jar:2.12.5]
    at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1601) ~[jackson-databind-2.12.5.jar:2.12.5]
    at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1375) ~[jackson-databind-2.12.5.jar:2.12.5]
    at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1322) ~[jackson-databind-2.12.5.jar:2.12.5]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeFromArray(BeanDeserializer.java:640) ~[jackson-databind-2.12.5.jar:2.12.5]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:221) ~[jackson-databind-2.12.5.jar:2.12.5]
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:197) ~[jackson-databind-2.12.5.jar:2.12.5]
    at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.readRootValue(DefaultDeserializationContext.java:322) ~[jackson-databind-2.12.5.jar:2.12.5]
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4593) ~[jackson-databind-2.12.5.jar:2.12.5]
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3601) ~[jackson-databind-2.12.5.jar:2.12.5]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:378) ~[spring-web-5.3.10.jar:5.3.10]
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:342) ~[spring-web-5.3.10.jar:5.3.10]
    at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:105) ~[spring-web-5.3.10.jar:5.3.10]
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:778) ~[spring-web-5.3.10.jar:5.3.10]
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:711) ~[spring-web-5.3.10.jar:5.3.10]
    at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:334) ~[spring-web-5.3.10.jar:5.3.10]
    at com.p1.controller.AccountController.getTrans(AccountController.java:56) ~[classes/:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-5.3.10.jar:5.3.10]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) ~[spring-web-5.3.10.jar:5.3.10]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) ~[spring-webmvc-5.3.10.jar:5.3.10]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) ~[spring-webmvc-5.3.10.jar:5.3.10]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) ~[spring-webmvc-5.3.10.jar:5.3.10]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.3.10.jar:5.3.10]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067) ~[spring-webmvc-5.3.10.jar:5.3.10]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.10.jar:5.3.10]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.10.jar:5.3.10]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.10.jar:5.3.10]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.53.jar:4.0.FR]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.10.jar:5.3.10]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.53.jar:4.0.FR]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.53.jar:9.0.53]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.10.jar:5.3.10]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.10.jar:5.3.10]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.10.jar:5.3.10]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.10.jar:5.3.10]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.10.jar:5.3.10]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.10.jar:5.3.10]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1726) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.53.jar:9.0.53]
    at java.base/java.lang.Thread.run(Thread.java:831) ~[na:na]

I am a beginner at this. Any help would be much appreciated.

CodePudding user response：

The getTrans API is returning just the array and not an object containing the array. So use Banking[].class as the type.

@GetMapping("/listofTrans/{cid}")
public Banking[] getTrans(@PathVariable Integer cid) {
    List<Account> a = acc.getByCid(cid);
    Banking[] items;
    for(Account a1:a) {
        items = restTemplate.getForObject("http://BankingClient/banking/" a1.getAno(), Banking[].class);
    }
    return items;
}

You can use the ObjectMappers constructCollectionType method to construct the collection type and deserialise with that:

@GetMapping("/listofTrans/{cid}")
public List<Banking> getTrans(@PathVariable Integer cid) {
    List<Account> a = acc.getByCid(cid);
    List<Banking> items = new ArrayList();
    ObjectMapper mapper = new ObjectMapper();
    CollectionType collectionType = mapper.getTypeFactory().constructCollectionType(List.class, Banking.class);
    for(Account a1:a) {
        String response = restTemplate.getForObject("http://BankingClient/banking/" a1.getAno(), String.class);
        items = objectMapper.readValue(response, collectionType);
    }
    return items;
}

But the simplest solution if you can update the getTrans API is to update it to return BankingList instead.

@GetMapping("/{ano}")
public BankingList getTrans(@PathVariable Integer ano) {
    BankingList list = new BankingList();
    list.setList(service.getTrans(ano));
    return list;
}