Hi,
I am using jackson for serialization/deserialization
I have no problem with
- simple objects
- objects with circular reference and no inheritance.
But when the object implies inheritance and circular reference, the
deserialization fails.
For example : I have an abstract superclass A ,which has one subclass B. A
can reference another A.
Here is a test case :
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,
property = "id", scope = A.class)
@JsonSubTypes( { @Type(value=B.class,name="B")} )
public abstract class A {
private String id;
private A replacement;
public A() {
super();
}
public A(String id) {
super();
this.id = id;
}
public String getId() {
return id;
}
public A getReplacement() {
return replacement;
}
public void setReplacement(A replacement) {
this.replacement = replacement;
}
public String toString() {
return "Id="+getId()+" " + this.getClass().getSimpleName();
}
}
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,
property = "id", scope = B.class)
public class B extends A {
public B() {
super();
}
public B(String id) {
super(id);
}
}
I tests it with 2 objects b1 and b2.
b1 references b2 and b2 references b1
public static void test() throws IOException {
// -- Mapper definition
ObjectMapper mapper = new ObjectMapper();
mapper.enable(SerializationFeature.USE_EQUALITY_FOR_OBJECT_ID);
mapper.enable(SerializationFeature.INDENT_OUTPUT);
mapper.enableDefaultTyping(DefaultTyping.NON_FINAL,As.PROPERTY);
// -- Test datas
List<A> aList = new ArrayList<>();
B b1 = new B("1");
B b2 = new B("2");
b1.setReplacement(b2);
b2.setReplacement(b1);
aList.add(b1);
aList.add(b2);
// -- Serialization
String jsonString;
jsonString = mapper.writeValueAsString(aList);
System.out.println(jsonString);
// -- DeSerialization
List<Object> list = mapper.readValue(jsonString, List.class);
System.out.println(list.size()+" elements :");
for (int i = 0; i< list.size(); i++ ) {
System.out.println(list.get(i).toString());
}
}
which yields to the following error on the readValue:
[ "java.util.ArrayList", [ {
"@class" : "B",
"id" : "1",
"replacement" : {
"@class" : "B",
"id" : "2",
"replacement" : "1"
}
}, "2" ] ]
Exception in thread "main" com.fasterxml.jackson.databind.deser.
UnresolvedForwardReference: Unresolved forward references for: Object id [1]
(for A) at [Source: [ "java.util.ArrayList", [ {
"@class" : "B",
"id" : "1",
"replacement" : {
"@class" : "B",
"id" : "2",
"replacement" : "1"
}
}, "2" ] ]; line: 7, column: 24].
at com.fasterxml.jackson.databind.deser.DefaultDeserializationContext.
checkUnresolvedObjectId(DefaultDeserializationContext.java:154)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(
ObjectMapper.java:3738)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.
java:2726)
at Test.test(Test.java:45)
at Test.main(Test.java:17)
What am i missing ?
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