Typed object with anchor throws Already had POJO for id

[almson]

Tested with jackson-dataformat-yaml 2.11.3

package foo

import com.fasterxml.jackson.annotation.JsonIdentityInfo;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonSubTypes.Type;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.annotation.JsonTypeInfo.Id;
import com.fasterxml.jackson.annotation.ObjectIdGenerators;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;
import java.util.List;
import org.junit.Test;

public class JacksonYamlTest {
    
    static class Container {
        @JsonProperty
        List<Base> list;
    }
    
    @JsonTypeInfo(use = Id.NAME)
    @JsonSubTypes({@Type(name="Derived", value=Derived.class)})
    @JsonIdentityInfo(generator = ObjectIdGenerators.StringIdGenerator.class)
    static class Base {
        
    }
    
    static class Derived extends Base {
        @JsonProperty
        String a;
    }
    
    @Test
    public void typedObjectIdTest() throws Exception {
        
        String yaml = "list:\n" +
                      "    - !Derived &id1\n" +
                      "        a: foo";
        
        ObjectMapper mapper = new ObjectMapper (new YAMLFactory());
        Container container = mapper.readValue (yaml, Container.class);
        
        System.out.println (((Derived)container.list.get(0)).a);
    }
}

throws

com.fasterxml.jackson.databind.JsonMappingException: Already had POJO for id (java.lang.String) [[ObjectId: key=id1, type=com.fasterxml.jackson.annotation.ObjectIdGenerators$StringIdGenerator, scope=NONE]] (through reference chain: JacksonYamlTest$Container["list"]->java.util.ArrayList[0])
	at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:397)
	at com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:368)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer._deserializeWithObjectId(CollectionDeserializer.java:406)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:277)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:249)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:26)
	at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:138)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:293)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:156)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4526)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3468)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3436)
	at JacksonYamlTest.typedObjectIdTest(JacksonYamlTest.java:41)

the problem is that SimpleObjectIdResolver.bindItem is called twice. Possibly, BeanDeserializerBase:1188 is not necessary at all.

[almson]

Btw, leaving out the anchor also causes parsing to fail with a different exception:

Missing type id when trying to resolve subtype of [simple type, class JacksonYamlTest$Base]: missing type id property '@type' (for POJO property 'list')
 at [Source: (StringReader); line: 3, column: 15] (through reference chain: JacksonYamlTest$Container["list"]->java.util.ArrayList[0])
	at com.fasterxml.jackson.databind.exc.InvalidTypeIdException.from(InvalidTypeIdException.java:43)
	at com.fasterxml.jackson.databind.DeserializationContext.missingTypeIdException(DeserializationContext.java:1794)
	at com.fasterxml.jackson.databind.DeserializationContext.handleMissingTypeId(DeserializationContext.java:1323)
	at com.fasterxml.jackson.databind.jsontype.impl.TypeDeserializerBase._handleMissingTypeId(TypeDeserializerBase.java:303)
	at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer._deserializeTypedUsingDefaultImpl(AsPropertyTypeDeserializer.java:166)
	at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer.deserializeTypedFromObject(AsPropertyTypeDeserializer.java:107)
	at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeWithType(BeanDeserializerBase.java:1209)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer._deserializeWithObjectId(CollectionDeserializer.java:395)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:277)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:249)
	at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:26)
	at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:138)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:293)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:156)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4526)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3468)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3436)
	at JacksonYamlTest.typedTest(JacksonYamlTest.java:54)

for input

list:
    - !Derived
        a: foo

Removing @JsonIdentityInfo solves the problem.

[cowtowncoder]

Looking into this: for some reason, OBject Id registration done twice. Not yet sure if it is due to buffering needed (due to type info), or differing Object Id handling wrt YAML (since it has native construct, unlike json and most other formats).

[cowtowncoder]

Or, possibly this is actually due to messy translocation of Object Id (YAML anchor) during YAMLParser handling, and nothing to do with databinding. Gnarly.

[cowtowncoder]

Ended up adding work-around (see FasterXML/jackson-annotations#180) that will avoid the issue, pass the test.

[almson]

What about the second problem? Should I open a separate issue? Reproducing it is to just leave out the anchor in the yaml.

[cowtowncoder]

@almson Yes, please open separate issue with changed reproduction, refer this issue as background.