Failed parsing for a LocalDate value while using Spring Data Rest - spring-boot

I am still a newbie with Spring Data Rest and I'm having some issues with it while I have to parse a LocalDate value to an endpoint. I have searched info's in other topics too but I'm still stucked, this is the problem:
I have one Entity with this code .
#Entity
#Table(name="calendario_parcheggio")
#Setter
#Getter
public class CalendarioParcheggio {
#Id
#Column(name="data_parcheggio")
#DateTimeFormat(iso = DateTimeFormat.ISO.DATE )
#JsonFormat(pattern="yyyy-MM-dd")
private LocalDate data;
#Column(columnDefinition = "ENUM('ATTIVO', 'ARCHIVIATO')")
#Enumerated(EnumType.STRING)
private Stato stato;
#OneToMany(cascade=CascadeType.ALL)
#JoinColumn(name="data_parcheggio")
private List<Parcheggio> parcheggio;
public enum Stato {
ATTIVO,
ARCHIVIATO,
}
}
It's an Entity linking the Date and its status for a Parking that works hourly.Matching this table on MySQL
CREATE TABLE calendario_parcheggio (
data_parcheggio DATE PRIMARY KEY,
stato ENUM ('ATTIVO','ARCHIVIATO') NOT NULL DEFAULT ('ATTIVO')
);
When I start the server everything is ok , but when i try (by browser or Postman) to check the data of a particular instance (in my case : "http://localhost:8080/parkingsystem/api/calendario-parcheggio/2022-10-18") ,I get this problem :
{"cause":
{"cause":
{"cause": null,
"message": "Text '2022-10-18' could not be parsed at index 2"
},
"message": "Parse attempt failed for value [2022-10-18]"
},
"message": "Failed to convert from type [java.lang.String] to type [java.time.LocalDate] for value '2022-10-18';
nested exception is java.lang.IllegalArgumentException: Parse attempt failed for value [2022-10-18]"
}
And this is the Repository
#RepositoryRestResource(collectionResourceRel="calendarioParcheggio", path="calendario-parcheggio")
public interface CalendarioParcheggioRepository extends JpaRepository<CalendarioParcheggio, LocalDate> {
}
Can you help me to find the solution please?I hope I have explained the problem well enough, my English is still in training :)

Related

Using projection with a interface in `#Query` annotation with a native query gives "Target type is not an interface and no matching Converter found"

I have a table with a clob in an oracle 19 database which I try to fetch with a native query using a #Query annotation with a projection from a Spring boot 2.7.4 application. I get the following error message:
java.lang.UnsupportedOperationException: Cannot project jdk.proxy2.$Proxy281 implementing java.sql.Clob,org.hibernate.engine.jdbc.WrappedClob,java.io.Serializable to java.lang.String; Target type is not an interface and no matching Converter found
The query from my repository class:
#Query(
value = """
select submission_id as "submissionId", text as "textAnswer"
from answer
where answer_id = :answerId
""",
nativeQuery = true)
public MyDTO findDTO(Long answerId);
My interface which I use for the projection:
public interface MyDTO {
String getTextAnswer();
}
From my domain object annotated with #Entity:
private String textAnswer;
My testcase which reproduce which reproduce this error. If I comment out the line with a.getTextAnswer() it runs ok.
#Test
public void findFormPublishedAnswersInterfaceDTOById() {
FormPublishedAnswersInterfaceDTO a = answerRepository.findFormPublishedAnswersInterfaceDTOById(21540241L);
assertEquals("test", a.getTextAnswer());
}
I have tried different hints I found by the help of google :) like annotating private String textAnswer with #Lob, #Type(type = "text") and #Column(name = "text", columnDefinition = "CLOB") without any luck.
If you read the exception carefully, you should understand that the JDBC driver reports that the type is a Clob, so your DTO must look like this instead:
public interface MyDTO {
Clob getTextAnswer();
}

Spring Data JPA - cannot insert to the databse - annotation problem?

I can't resolve the problem with inserting values into my database.
I've two very basic and simple classes - Car and Model. I want to store the model ID value for each vehicle in the car class. You know, for the sake of simplicity I assume every car has no brand, only model (eg. Auris, Civic, F150, Challenger etc.).
#Data
#Entity
public class Car {
#Id
#GeneratedValue(strategy= GenerationType.AUTO)
private Long id;
#ManyToOne
private Model model;
}
#Entity
#Data
#NoArgsConstructor(access=AccessLevel.PRIVATE, force=true)
#RequiredArgsConstructor
public class Model {
#Id
private final Long id;
private final String name;
private final int price;
}
But the problem is I got that error
Field error in object 'car' on field 'model': rejected value [Model(id=2, name=Civic)]; codes [typeMismatch.samochod.model,typeMismatch.model,typeMismatch.com.CarDealer.Model,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [car.model,model]; arguments []; default message [model]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'com.CarDealer.Model' for property 'model'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [java.lang.Long] for value 'Model(id=2, name=Civic)'; nested exception is java.lang.NumberFormatException: For input string: "Model(id=2,name=Civic)"]]
I'd appreciate any help.

Heroku shows Whitelabel Error Page but not on localhost

I have a Spring boot application with PostgreSQL. The app run very well on localhost with all the data from the PostgreSQL. I have successful upload the app to Heroku and migrated the database to Heroku PostgreSQL. The problem is when I click some of the links that retrieve data from PostgreSQL shows a White Error page. But on localhost every thing works fine.
Below is the Controller that link to the White Error Page.
#Controller
public class MahubiriController {
#Autowired
private MisaleRepository misaleRepository;
#GetMapping("/masomo/somolaleo")
public String masomoAngalia(Model model){
model.addAttribute("masomoYote", misaleRepository.findAllOrderByDateDesc() );
return "masomo";
} }
Below is the repository
#Repository
#Transactional
public interface MisaleRepository extends JpaRepository <Misale, String> {
#Query(value ="SELECT * FROM misale ORDER BY date DESC" , nativeQuery = true)
public List<Misale> findAllOrderByDateDesc();
}
Below is the Entity for the particular object
#Entity
#Table(name = "misale")
public class Misale {
#Id
#Column(name ="date")
private String date;
#Lob
#Column(name ="first_reading", columnDefinition="text")
private String firstReading;
#Lob
#Column(name ="second_reading", columnDefinition="text")
private String secondReading;
// Constructors, getter and setters
}
Below is the Query used to create the particular table on Postgresql
CREATE TABLE misale(date VARCHAR(20) NOT NULL PRIMARY KEY,
first_reading TEXT NOT NULL,
second_reading TEXT,gospel TEXT NOT NULL);
What could possibly be wrong on Heroku to lead to a White Error Page and not on a local host.
Update :
After implementing the Exception handling as suggested by # krishnkant jaiswal, I receive message "Unable to access lob str…le to access lob stream" as below.
timestamp "2021-04-03T01:26:43.791+00:00"
message "Unable to access lob stream; nested exception is org.hibernate.HibernateException: Unable to access lob stream"
details "uri=/masomo/somolaleo"
With the help of Exception handling and a long research, On my side it shows that you cannot use
#Lob and #Column(columnDefinition="text")
So I had to remove #Lob and leave #Column(columnDefinition="text")
#Column(columnDefinition="text")
Now I cloud retrieve the data from PostgreSQL without error.
Hope it might help someone else in future.

Spring WebClient Post body not getting passed

I am trying to use WebClient to Post a loan object to another microservice which saves this object in a DB. So theoretically the body (JSON loan object) should just be passed on to the API of the DB service. Somehow, I can't figure out how to accomplish this.
This is the API that accepts the JSON loan object:
Mapping: localhost:8081/loans
#PostMapping
public <T extends Loan> void addLoan(#Valid #NonNull #RequestBody T loan) {
loanService.createLoan(loan);
}
It then calls the loanService which should pass on the loan object to the DB-service API
public <T extends Loan> T createLoan(T loan) {
ParameterizedTypeReference<T> typeReference = new ParameterizedTypeReference<T>(){};
T a = client.post().uri("/loans").body(BodyInserters.fromValue(loan)).retrieve().bodyToMono(typeReference).block();
return a;
}
This is the API of that DB service:
Mapping: localhost:8080/api/v1/loans
#PostMapping
#ResponseBody
public <T extends Loan> T createLoan(#RequestBody T loan) {
return loanService.createLoan(loan);
}
And here is its service:
public <T extends Loan> T createLoan(T Loan) {
return (T) loanRepository.save(Loan);
}
If I just pass a loan object directly to the DB service API, everything works fine. But if I pass it to the other API, I get the following error:
"status": 500,
"error": "Internal Server Error",
"trace": "org.springframework.web.reactive.function.client.WebClientResponseException$InternalServerError: 500 Internal Server Error from POST http://localhost:8080/api/v1/loans/\n\tat org.springframework.web.reactive.function.client.WebClientResponseException.create(WebClientResponseException.java:201)\n\tSuppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: \nError has been observed at the following site(s):\n\t|_ checkpoint ⇢ 500 from POST http://localhost:8080/api/v1/loans/ [DefaultWebClient]\nStack trace:\n\t\tat org.springframework.web.reactive.function.client.WebClientResponseException.create(WebClientResponseException.java:201)\n\t\tat org.springframework.web.reactive.function.client.DefaultClientResponse.lambda$createException$1(DefaultClientResponse.java:216)\n\t\tat reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:106)\n\t\tat reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79)\n\t\tat reactor.core.publisher.FluxDefaultIfEmpty$DefaultIfEmptySubscriber.onNext(FluxDefaultIfEmpty.java:99)\n\t\tat reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:127)\n\t\tat reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onNext(FluxContextWrite.java:107)\n\t\tat reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:295)\n\t\tat reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:337)\n\t\tat reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1784)\n\t\tat reactor.core.publisher.MonoCollect$CollectSubscriber.onComplete(MonoCollect.java:159)\n\t\tat reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:142)\n\t\tat reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:259)\n\t\tat reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:142)\n\t\tat reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:383)\n\t\tat reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:396)\n\t\tat reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:452)\n\t\tat reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:664)\n\t\tat reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:94)\n\t\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)\n\t\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)\n\t\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)\n\t\tat io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103)\n\t\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)\n\t\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)\n\t\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)\n\t\tat io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436)\n\t\tat io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:324)\n\t\tat io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:296)\n\t\tat io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251)\n\t\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)\n\t\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)\n\t\tat io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)\n\t\tat io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)\n\t\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)\n\t\tat io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)\n\t\tat io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)\n\t\tat io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:795)\n\t\tat io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:480)\n\t\tat io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:378)\n\t\tat io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)\n\t\tat io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)\n\t\tat io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)\n\t\tat java.base/java.lang.Thread.run(Thread.java:832)\n\tSuppressed: java.lang.Exception: #block terminated with an error\n\t\tat reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:99)\n\t\tat reactor.core.publisher.Mono.block(Mono.java:1679)\n\t\tat de.rwth.swc.lab.ws2021.daifu.businesslogic.services.LoanService.createLoan(LoanService.java:39)\n\t\tat de.rwth.swc.lab.ws2021.daifu.businesslogic.api.LoanController.addLoan(LoanController.java:28)\n\t\tat java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\n\t\tat java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)\n\t\tat java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\n\t\tat java.base/java.lang.reflect.Method.invoke(Method.java:564)\n\t\tat org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:197)\n\t\tat org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:141)\n\t\tat org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)\n\t\tat org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:893)\n\t\tat org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:807)\n\t\tat org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)\n\t\tat org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1061)\n\t\tat org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:961)\n\t\tat org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)\n\t\tat org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)\n\t\tat javax.servlet.http.HttpServlet.service(HttpServlet.java:652)\n\t\tat org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)\n\t\tat javax.servlet.http.HttpServlet.service(HttpServlet.java:733)\n\t\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)\n\t\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\n\t\tat org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)\n\t\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\n\t\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\n\t\tat org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)\n\t\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\n\t\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\n\t\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\n\t\tat org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)\n\t\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\n\t\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\n\t\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\n\t\tat org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)\n\t\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)\n\t\tat org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)\n\t\tat org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)\n\t\tat org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)\n\t\tat org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)\n\t\tat org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)\n\t\tat org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)\n\t\tat org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)\n\t\tat org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)\n\t\tat org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)\n\t\tat org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)\n\t\tat org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)\n\t\tat org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)\n\t\tat org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590)\n\t\tat org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)\n\t\tat java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)\n\t\tat java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)\n\t\tat org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)\n\t\tat java.base/java.lang.Thread.run(Thread.java:832)\n",
"message": "500 Internal Server Error from POST http://localhost:8080/api/v1/loans/",
"path": "/loans/"
This is the server-side error:
Servlet.service() for servlet [dispatcherServlet] in context with path [/api/v1] threw exception [Request processing failed; nested exception is org.springframework.dao.DataIntegrityViolationException: not-null property references a null or transient value : de.rwth.swc.lab.ws2021.daifu.dataservice.data.models.loans.PrivateLoan.customer; nested exception is org.hibernate.PropertyValueException: not-null property references a null or transient value : de.rwth.swc.lab.ws2021.daifu.dataservice.data.models.loans.PrivateLoan.customer] with root cause org.hibernate.PropertyValueException: not-null property references a null or transient value : de.rwth.swc.lab.ws2021.daifu.dataservice.data.models.loans.PrivateLoan.customer
And finally, this is the POST-body:
{
"amount": 10000.00,
"balance": -2000.00,
"customer": {"id": 1},
"interest": 0.06,
"status": "TIMELY",
"reason": "Some reaseon",
"type": "privateLoan"
}
The error says the "not-null property references a null or transient value" but the exact same request works for a direct POST-request to the 2nd API which doesn't make sense to me.
Here is the loan class:
#Entity
#Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
#Getter
#Setter
#NoArgsConstructor
#JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type")
#JsonSubTypes({
#JsonSubTypes.Type(value = CarLoan.class, name = "carLoan"),
#JsonSubTypes.Type(value = ConstructionLoan.class, name = "constructionLoan"),
#JsonSubTypes.Type(value = Mortgage.class, name = "mortgage"),
#JsonSubTypes.Type(value = PrivateLoan.class, name = "privateLoan"),
#JsonSubTypes.Type(value = PropertyLoan.class, name = "propertyLoan")
})
#ApiModel(
discriminator = "type",
subTypes = {CarLoan.class, ConstructionLoan.class, Mortgage.class, PrivateLoan.class, PropertyLoan.class}
)
public abstract class Loan {
#Id
#GeneratedValue(strategy = GenerationType.TABLE)
#Column(name = "id")
#ApiModelProperty(required = false, hidden = true)
protected Integer id;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "customer_id", nullable = false)
#JsonBackReference(value = "customer-loans")
protected Customer customer;
#OneToMany(mappedBy = "loan", cascade = CascadeType.ALL)
#JsonManagedReference(value = "loan-loanRates")
private Set<LoanRate> loanRates;
#NonNull
protected Double amount;
#NonNull
protected Double interest;
#NonNull
protected Double balance;
#NonNull
protected LoanStatus status;
public enum LoanStatus {
TIMELY("timely"),
GRACE_PERIOD("grace period"),
DEFAULT("default"),
DEFICIT("deficit"),
IRRECOVERABLE_DEBT("irrecoverable debt"),
CLOSED("closed");
#Getter
private String stringRepresentation;
private LoanStatus(String s) {
this.stringRepresentation = s;
}
}
public <T extends Loan> boolean isOfSameInstance(T otherLoan) {
return (this.getClass().equals(otherLoan.getClass()));
}
}
Let me know if I should post anything else.
Thanks in advance.
The problem is due to the models being used in the projects. As your are reusing the model classes of the one webservice which offers the CRUD api for the backend, you are also reusing the jackson's #JsonManagedReference and #JsonBackReference. This leads to null values for the models being defined as the back reference, such as the customer in you loan class. Jackson does not serialize such tagged objects to JSON in order to not run into a stackoverflow due to infinite recursion. Thus, when you serialize a loan model in your service and send the request to the other service, jackson nulls the back reference, e.g. customer in the loan model and the 2nd webservice therefore receives an invalid loan model, since a loan model is required to have a customer not to be null.
I suggest to either remove the jackson annotations from the models in the service you develop, which would required copy pasted model classes (on the one side the classes using the required jackson annotations in the web service, and on the other side the classes not using these in the other web service). However, this solution has the typical disadvantages of duplicated code. The more elegant but more complicated solution will be to implement a custom jackson serializer and deserializer by specializing jackson's StdSerializer<Loan> and StdDeserializer<Loan>. These custom serializers and deserializers should override its serialize(T value, JsonGenerator gen, SerializerProvider provider) respectively its deserialize(JsonParser, DeserializationContext) method such that the #JsonManagedReference and #JsonBackReference, as well as, if being used, #JsonIgnore annotations in the model are being ignored.
It might be sufficient to just implement a custom serializer. However, I guess that you will also run into problems when receiving a response from the other web service when not using a custom deserializer.
This error may happen if the customer object in the loan you are trying to save is null or not yet added to the database (even though it is set in loan). You should check before saving the Loan in the DB if customer is null or not. If not, and if it is a customer not yet in the database, you should consider adding it first or specify CascadeType.PERSIST in the relation type annotation. In any case, it would be better if you post the entire model that both services are using.

How to create a new entity with association

Let's say i have a form on the frontend with usual fields and dropdowns.
In those dropdowns user is able to select an option, and each option is linked to an entity in Spring data JPA;
Dropdowns contain some label and a link to corresponding entity as a value.
This value is then passed in a POST-request to a PagingAndSorting repository of an entity which we wish to create.
Let's say it's a user with username and he must be associated with one of the offices (Also an entity):
#Data
#Builder
#Entity
#NoArgsConstructor
#AllArgsConstructor
#Table(name="users")
public class User{
#Id
#Coluemn(name="USER_ID")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long userId;
#Column(name="USER_NAME", nullable=false)
private String userName;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name="OFFICE_ID", **nullable=false**)
private Office office;
}
My first guess would be:
Sending POST-request to http://localhost:8080/api/users/
contentType:'application/json'
{"userName":"Anton","office":"http://localhost:8080/api/offices/1"}
But it throws an exception
{
"cause": {
"cause": null,
"message": "Cannot construct instance of `test.domain.Office` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/api/offices/1')\n at [Source: (org.apache.catalina.connector.CoyoteInputStream); line: 1, column: 160] (through reference chain: test.domain.User[\"office\"])"
},
"message": "JSON parse error: Cannot construct instance of `test.domain.Office` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/api/offices/1'); nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `test.domain.Office` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('http://localhost:8080/api/office/1')\n at [Source: (org.apache.catalina.connector.CoyoteInputStream); line: 1, column: 160] (through reference chain: test.domain.User[\"office\"])"
}
What am i doing wrong?
You are sending a URL resource as a string in place of a JSON object and expecting some magic to happen between Spring and jackson to look up the value. Naturally this is not what is happening and Jackson is attempting to bind the string value of the URL to the Office field. This fails of course because it does not know how to create an Office object from a string.
A possible solution is to make a distinction between your Entity Objects (those which represent your database tables) and DTO's (Data Transfer Objects) which in this cause represent your contract with your client. When doing this you could receive a User Object like so:
#Data
#Builder
#NoArgsConstructor
#AllArgsConstructor
public class User{
private Long userId;
private String userName;
private Long officeId;
}
Now you can simply send an office id instead of a URL and in your code use a Spring data repository to lookup the office object. After that you can then construct your Entity User object like the one you have shown above and persist it.
Turns out it was because i used Lombok, which generated it's own constructor.
To make it work i just needed to set #AllArgsConstructor like this:
#AllArgsConstructor(suppressConstructorProperties = true)
Now it works as i expected:
Json to send to http://localhost:8080/api/users:
{
"userName":"Anton",
"office":"http://localhost:8080/api/offices/1"
}
Which returns:
{
"userName":"Anton",
"_links": {
"self": {
"href": "http://localhost:8080/api/users/28"
},
"user": {
"href": "http://localhost:8080/api/users/28"
},
"office": {
"href": "http://localhost:8080/api/users/28/office"
}
}
}

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