Hi Carlos Here is an example of subclassing with Jackson using the @Type annotation that I did many years ago:
https://github.com/gbif/gbif-api/tree/master/src/main/java/org/gbif/api/model/registry/eml/temporal It decorates the JSON with an extra field ("@Type" in this case) which instructs the deserializers which Object to instantiate. I'm not sure if newer Jackson versions have changed. I haven't considered if this is appropriate or not in your case, but I hope this helps with the Jackson bit of your question at least. Best wishes, Tim On Wed, May 9, 2018 at 7:02 PM, Carlos Alonso <car...@mrcalonso.com> wrote: > Hi everyone!! > > I'm working on BEAM-4257 issue and the approach I'm following is to create > a new class 'BigQueryInsertError' that also extends 'GenericJson' and that > contains three keys 'TableRow row', 'TableDataInsertAllResponse.InsertErrors > error', and 'TableReference ref' and use this type as the contained items > returned by WriteResults.getFailedInserts > > I have now to create a Coder for this new type and I'm following the > TableRowJsonCoder way https://github.com/apache/ > beam/blob/master/sdks/java/io/google-cloud-platform/src/ > main/java/org/apache/beam/sdk/io/gcp/bigquery/TableRowJsonCoder.java#L34 by > relying on Jackson's ObjectMapper and StringUtf8Encoder. > > The problem is that I always get errors when deserialising as it > deserialises the inner TableRow as a LinkedHashMap and fails when trying to > assign it. Here you can see the full stacktrace: https://pastebin. > com/MkUD9L3W > > Testing it a bit further I've spotted other GenericJson subclasses that > cannot be encoded/decoded following that method. For example > TableDataInsertAllResponse.InsertErrors itself. See the example below: > > TableDataInsertAllResponse.InsertErrors err = new > TableDataInsertAllResponse.InsertErrors().setIndex(0L); > ObjectMapper mapper = new > ObjectMapper().disable(SerializationFeature.FAIL_ON_EMPTY_BEANS); > mapper.readValue(mapper.writeValueAsString(err), > TableDataInsertAllResponse.InsertErrors.class); > > > Fails with a similar error, but in this case is because it deserialises > the index into an int: https://pastebin.com/bzXMR3z5 > > So a couple of questions here: > * Which is the appropriate way of encoding/decoding GenericJson > subclasses? (Maybe this issues can be tackled using Jackson's type > annotations, but I'm quite a newbie on Jackson and I couldn't figure out > how) > * This will (hopefully) be my very first contribution to Apache Beam and > I'd like to get some feedback/comments/ideas/... on the issue and the > suggested solution. > > Thanks everyone! >
