JSONProvider builds wrong String

Looking at my backlog I found a very interesting ticket:

As a consumer of JSON web services, I would like the services to render fields with consistent types regardless of the content. When postal codes begin with zero, they are rendered as strings. When they begin with a non-zero character, they are rendered as numbers. This makes handling the JSON responses very cumbersome and causes hard to track down bugs in our code. 

It would be better if the conversion checked the type in the xsd (in the case of postal codes, string) and rendered it accordingly. 

Weird, isn't it? Then I realize, I wasn't the only one with this issue, a found a few other clueless developers with the same problem (look here and here), so that, I wasn't alone.

But so far no one had an answer, until I checked the code of my JSONProvider, this one: org.apache.cxf.jaxrs.provider.JSONProvider

My conclusion was simple, depending on the value of the string passed to the Converter, it will be casted to Boolean, String or Number.

There are 2 choices: Create my own custom JSONProvider extending from the original (and try to fix the world) or implement another which really worked as expected.

In a few words, I chose JacksonJsonProvider, however I had to customize it a little bit, because I needed to fix the issue and not create a new one (i needed the same output), and so far this is the result:

This is the original output { "postalCode": [ { "activeFlag": true, "areaCode": 603, "code": "03033", "createdOn": "2001-12-18", "isoCodeAlpha2": "US", "isoCodeAlpha3": "USA", "isoCodeNumeric": 840, "kbsPostalCodeId": 10998, "latitude": 42.740602, "longitude": -71.676612, "modifiedOn": "2006-12-08" }, { "activeFlag": true, "areaCode": 412, "code": 15102, "createdOn": "2001-12-18", "isoCodeAlpha2": "US", "isoCodeAlpha3": "USA", "isoCodeNumeric": 840, "kbsPostalCodeId": 15893, "latitude": 40.323747, "longitude": -80.037982, "modifiedOn": "2006-12-08" } ] }

This is my implementation public class JacksonJsonProvider extends org.codehaus.jackson.jaxrs.JacksonJsonProvider { private static final Logger log = Logger.getLogger(JacksonJsonProvider.class); @Override public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) { boolean result = false; log.debug("Is Writeable? type="+type+", genericType="+genericType+", annotations="+annotations+", mediaType="+mediaType); result = super.isWriteable(type, genericType, annotations, mediaType); log.debug("Result="+result); if (String.class.equals(type)) { //pass strings as-is, they are most likely cached JSON responses return false; } else { return result;//return super.isWriteable(type, genericType, annotations, mediaType); } } public JacksonJsonProvider() { super(); ObjectMapper objectMapper = new ObjectMapper(); final Annotations[] BASIC_ANNOTATIONS = {Annotations.JACKSON, Annotations.JAXB}; objectMapper.configure(SerializationConfig.Feature.AUTO_DETECT_FIELDS, true); objectMapper.configure(SerializationConfig.Feature.INDENT_OUTPUT, true); objectMapper.configure(SerializationConfig.Feature.SORT_PROPERTIES_ALPHABETICALLY, true); objectMapper.configure(SerializationConfig.Feature.USE_ANNOTATIONS, true); objectMapper.configure(SerializationConfig.Feature.WRAP_ROOT_VALUE, true); super.setMapper(objectMapper); super.setAnnotationsToUse(BASIC_ANNOTATIONS); } }
And my new output { "ArrayList": [ { "activeFlag": true, "areaCode": "603", "code": "03033", "createdOn": "2001-12-18", "isoCodeAlpha2": "US", "isoCodeAlpha3": "USA", "isoCodeNumeric": 840, "kaplanPremierEligibleFlag": false, "kbsPostalCodeId": 10998, "latitude": 42.740602, "longitude": -71.676612, "modifiedOn": "2006-12-08" }, { "activeFlag": true, "areaCode": "412", "code": "15102", "createdOn": "2001-12-18", "isoCodeAlpha2": "US", "isoCodeAlpha3": "USA", "isoCodeNumeric": 840, "kaplanPremierEligibleFlag": true, "kbsPostalCodeId": 15893, "latitude": 40.323747, "longitude": -80.037982, "modifiedOn": "2006-12-08" } ] } I still have something to fix-customize because that "ArrayList" looks ugly though, but code and areCode now make sense, because they match my XSD and Pojo as well.