Map key deserializerModifiers ignored

[alfonsobonso]

We have a module that extends simple model to allow us to accept enum names in lower case in a fairly generic manner
Inside that we add the modifyKeyDeserializer

The incoming class (using immutables) is mapped to a guava immutable map.
Walking through the code:

com.fasterxml.jackson.datatype.guava.deser.ImmutableMapDeserializer.createContextual
calls DeserializationContext.findKeyDeserializer
calls DeserializerCache.findKeyDeserializer
calls BasicDeserializerFactory.createKeyDeserializer

which has the code:

        // the only non-standard thing is this:
        if (deser == null) {
            if (type.isEnumType()) {
                return _createEnumKeyDeserializer(ctxt, type);
            }
            deser = StdKeyDeserializers.findStringBasedKeyDeserializer(config, type);
        }

Since we are an enum type, it returns the value in the _createEnumKeyDeserializer, which is the standard enum deserializer.
Below that block is the check for the hasDeserializerModifiers, but since we have returned already, it is never called, so we can't override the behaviour.

Module fragment:

    setDeserializerModifier(new BeanDeserializerModifier() {
                @Override
                @SuppressWarnings("unchecked")
                public JsonDeserializer<Enum> modifyEnumDeserializer(
                        DeserializationConfig config,
                        final JavaType type,
                        BeanDescription beanDesc,
                        final JsonDeserializer<?> deserializer) {
                    return new JsonDeserializer<Enum>() {
                        @Override
                        public Enum deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {
                            Class<? extends Enum> rawClass = (Class<Enum<?>>) type.getRawClass();
                            return Enum.valueOf(rawClass, jp.getValueAsString().toUpperCase());
                        }
                    };
                }

                @Override
                public KeyDeserializer modifyKeyDeserializer(
                        DeserializationConfig config,
                        JavaType type,
                        KeyDeserializer deserializer) {
                    if (!type.isEnumType()) {
                        return super.modifyKeyDeserializer(config, type, deserializer);
                    }
                    return new KeyDeserializer() {
                        @Override
                        @SuppressWarnings("unchecked")
                        public Object deserializeKey(String key, DeserializationContext ctxt)
                                throws IOException, JsonProcessingException {
                            Class<? extends Enum> rawClass = (Class<Enum<?>>) type.getRawClass();
                            return Enum.valueOf(rawClass, key.toUpperCase());
                        }
                    };
                }
            });

I appreciate the code around here is fairly complex.

Related issues (possibly):
#749
#1313

[cowtowncoder]

Thank you for reporting this. Couple of questions first:

• Which jackson version is this (verified) with?
• Does this also occur with standard JDK collections, or just with Guava ones?

[alfonsobonso]

Version is 2.8.4. I had also been running with 2.6.4, which had the same issue, and upgraded as part of my digging.
I confirm this is also happening with standard JDK collections.

[cowtowncoder]

Thank you for verifying this. Being able to test with JDK collections makes it bit easier to repro with just databind.

[alfonsobonso]

Fast! Thank you very much.