@JsonTypeInfo with As.EXTERNAL_PROPERTY doesn't work if external type property is referenced more than once

[Starkom]

Test model:

    public static interface F1 {}

    public static class A implements F1 {
        public String a;
    }

    public static class B implements F1 {
        public String b;
    }

    public static interface F2 {}

    public static class C implements F2 {
        public String c;
    }

    public static class D implements F2{
        public String d;
    }

    public static class Container {
        public String type;

        @JsonTypeInfo(use = Id.NAME, property = "type", include = As.EXTERNAL_PROPERTY)
        @JsonSubTypes({
                @JsonSubTypes.Type(value = A.class, name = "1"),
                @JsonSubTypes.Type(value = B.class, name = "2")})
        public F1 field1;

        @JsonTypeInfo(use = Id.NAME, property = "type", include = As.EXTERNAL_PROPERTY)
        @JsonSubTypes({
                @JsonSubTypes.Type(value = C.class, name = "1"),
                @JsonSubTypes.Type(value = D.class, name = "2")})
        public F2 field2;
    }

Test JSON:

{
 "type" : "1",
 "field1" : {
   "a" : "AAA"
 },
 "field2" : {
   "c" : "CCC"
 }
}

Stacktrace:

com.fasterxml.jackson.databind.JsonMappingException: Unexpected token (VALUE_NULL), expected VALUE_STRING: need JSON String that contains type id (for subtype of F2)
at [Source: java.io.StringReader@b2fe7658; line: 9, column: 1]
at com.fasterxml.jackson.databind.DeserializationContext.wrongTokenException(DeserializationContext.java:668)
at com.fasterxml.jackson.databind.jsontype.impl.AsArrayTypeDeserializer._locateTypeId(AsArrayTypeDeserializer.java:144)
at com.fasterxml.jackson.databind.jsontype.impl.AsArrayTypeDeserializer._deserialize(AsArrayTypeDeserializer.java:101)
at com.fasterxml.jackson.databind.jsontype.impl.AsArrayTypeDeserializer.deserializeTypedFromObject(AsArrayTypeDeserializer.java:69)
at com.fasterxml.jackson.databind.deser.AbstractDeserializer.deserializeWithType(AbstractDeserializer.java:106)
at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:462)
at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:107)
at com.fasterxml.jackson.databind.deser.impl.ExternalTypeHandler._deserializeAndSet(ExternalTypeHandler.java:253)
at com.fasterxml.jackson.databind.deser.impl.ExternalTypeHandler.complete(ExternalTypeHandler.java:162)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeWithExternalTypeId(BeanDeserializer.java:715)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeWithExternalTypeId(BeanDeserializer.java:664)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:274)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2888)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2034)

The reason:

com.fasterxml.jackson.databind.deser.impl.ExternalTypeHandler:262

    public static class Builder
    {
        private final ArrayList<ExtTypedProperty> _properties = new ArrayList<ExtTypedProperty>();
        private final HashMap<String, Integer> _nameToPropertyIndex = new HashMap<String, Integer>();

        // note: signature changed between 2.1.0 and 2.1.1 (alas!)
        public void addExternal(SettableBeanProperty property, TypeDeserializer typeDeser)
        {
            Integer index = _properties.size();
            _properties.add(new ExtTypedProperty(property, typeDeser));
            _nameToPropertyIndex.put(property.getName(), index);
            _nameToPropertyIndex.put(typeDeser.getPropertyName(), index);
        }

addExternal() method is called in property loop, but _nameToPropertyIndex is Map, so addExternal() can't be called twice correctly for property "type".

So _nameToPropertyIndex doesn't contain type=0: {field1=1, type=1, field2=0}

I think type of _nameToPropertyIndex should be changed from HashMap[String, Integer] to HashMap[String, Set[Integer]]. It occurs several changes in ExternalTypeHandler. I've patched jar locally and it solved my problem.

[cowtowncoder]

Hmmh. This isn't actually a use case I was familiar with (or design to support)... but ok, if it can be supported, all the better. :)

[dvdh]

@cowtowncoder is this a supported use case now?

[cowtowncoder]

@dvdh No changes have been made, and it is unlikely I will have time to work on this in near future. So no.

[dvdh]

Thanks @cowtowncoder

[ABHINAVKR]

As suggested by @Starkom i have done the changes , but two tests are failing after those changes.

Failed tests:
TestExternalId.testIssue798:376 null
Tests in error:
TestExternalId.testInverseExternalId928:505 NullPointer
Tests run: 1513, Failures: 1, Errors: 1, Skipped: 0

Any suggestions @cowtowncoder for fixing these TESTS

[cowtowncoder]

@ABHINAVKR you would need bit more context (stack traces). And also know which Jackson versions they are for.

[cowtowncoder]

Seems fixable; ideally would avoid use of Set, but perhaps could use Collections.singleton() for the common case of just a single id. Most likely fixing for 2.9, to minimize risk of regression.

[cowtowncoder]

Finally found time to fix this; also improved testing a bit to cover other cases (differently ordered input, with and without additional type property).