JSON Scalar best practice?

We’re using GraphQL to implement a custom JSON scalar that maps internally to a Jackson JsonNode.

What is the best practice for doing this? The challenge we’re facing is the best way to turn an ObjectValue into a Map<String,Object> or a JsonNode for parsing inputs to mutations.

[bbakerman]

See https://github.com/graphql-java/graphql-java-extended-scalars for a JSON scalar.

[loganvolkers]

So we copied the approach from GraphQL.js.

• Hopefully this helps other people implement custom scalars
• Or the GraphQL.java maintainers tell us this is the wrong approach.

    static JsonNode valueToJson(Value v) {
        if (v instanceof BooleanValue) {
            return JsonNodeFactory.instance.booleanNode(BooleanValue.class.cast(v).isValue());
        } else if (v instanceof EnumValue) {
            return JsonNodeFactory.instance.textNode(EnumValue.class.cast(v).getName());
        } else if (v instanceof FloatValue) {
            return JsonNodeFactory.instance.numberNode(FloatValue.class.cast(v).getValue());
        } else if (v instanceof IntValue) {
            return JsonNodeFactory.instance.numberNode(IntValue.class.cast(v).getValue());
        } else if (v instanceof NullValue) {
            return JsonNodeFactory.instance.nullNode();
        } else if (v instanceof StringValue) {
            return JsonNodeFactory.instance.textNode(StringValue.class.cast(v).getValue());
        } else if (v instanceof ArrayValue) {
            final ArrayNode result = JsonNodeFactory.instance.arrayNode();
            for (final Value v2 : ArrayValue.class.cast(v).getValues()) {
                result.add(valueToJson(v2));
            }
            return result;
        } else if (v instanceof ObjectValue) {
            final ObjectNode result = JsonNodeFactory.instance.objectNode();
            for (final ObjectField f : ObjectValue.class.cast(v).getObjectFields()) {
                result.set(f.getName(), valueToJson(f.getValue()));
            }
            return result;
        } else {
            throw new IllegalStateException(String.format("Unsupported value type: %s", v.getClass()));
        }
    }