I am calling an endpoint in which it returns an object. In this object it contains some fields and also a field of another type of object. Eg
class ResponseObject{
private final boolean success;
private final String message;
private final DifferentType different;
}
I am calling the endpoint via RestTemplate:
private LogonResponseMessage isMemberAuthenticated(UserCredentialDomain userCredentialDomain)
{
RestTemplate restTemplate = new RestTemplate();
return restTemplate.getForObject(
"http://abc.local:8145/xyz/member/authenticate/{memberLoginName}/{password}", ResponseObject.class,
userCredentialDomain.getUsername(), userCredentialDomain.getPassword());
}
So my consuming app is giving this error:
com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `fgh.thg.member.DifferentTypeABC` (no Creators, like default constructor, exist): cannot deserialize from Object v
alue (no delegate- or property-based Creator)
I am aware that it's telling me to put a default constructor in the DifferentTypeABC class in order for jackson to deserialise it but i can't do that easily as I'll need to update the dependency on apps that the DifferentTypeABC is in across several different repos.
So i was wondering if there is a way of configuring RestTemplate or jackson on the consuming app so that it ignores attempting to deserialise objects if it doesn't contain a default constructor? To be honest, I am pretty much interested in the success
and message
fields on the response object.
Another way to solve the problem is by enhancing DifferentType
in this module using Jackson creator Mixin
. Below is an example:
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.Data;
import java.io.IOException;
public class Test {
public static void main(String[] args) throws IOException {
ObjectMapper mapper = new ObjectMapper();
mapper.setVisibility(mapper.getVisibilityChecker()
.withFieldVisibility(JsonAutoDetect.Visibility.ANY)
.withGetterVisibility(JsonAutoDetect.Visibility.NONE)
.withSetterVisibility(JsonAutoDetect.Visibility.NONE)
.withCreatorVisibility(JsonAutoDetect.Visibility.NONE));
mapper.addMixIn(DifferentType.class, DifferentTypeMixin.class);
String raw = "{\"message\": \"ok\", \"differentType\": {\"name\": \"foo bar\"}}";
ResponseObject object = mapper.readValue(raw, ResponseObject.class);
System.out.println(mapper.writeValueAsString(object));
}
@Data
static class ResponseObject {
private String message;
private DifferentType differentType;
}
static class DifferentType {
private String name;
public DifferentType(String name) {
this.name = name;
}
}
public static abstract class DifferentTypeMixin {
@JsonCreator
DifferentTypeMixin(@JsonProperty("name") String name) {
}
}
}
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