On Mon, 15 Jun 2020 14:49:05 +0300 Andrus Adamchik <and...@objectstyle.org> wrote:
> > On Jun 9, 2020, at 5:54 PM, John Huss <johnth...@gmail.com> wrote: > > > > 2) Regarding skipping parsing when just going straight back out > > again to serialization - I have felt the reluctance (like you) of > > parsing this in those cases. But one thing to think about is that > > the parser/serializer (let's say Jackson in this case) may have > > special rules for how types are outputted like pretty/minified, > > sorted/unsorted, string/number (for BigDecimal). So skipping that > > parse/serialization may not actually be desirable, at least not in > > every case. > > Was discussing this offline with Nikita and stumbled on what can be a > good solution: > > 1. Cayenne would provide a set of "unparsed" wrapper types (Wkt, > Json, etc.) and the JDBC/SQL machinery around them (ExtendedType, > SqlTreeProcessor). 2. A user who needs a parsed version would create > their own types (e.g. WktParsed, JsonParsed), and would connect them > to Cayenne via a custom ValueObjectType [1] (e.g. > ValueObjectType<WktParsed, Wkt>). > > Such a two-tier approach would allow the users to map persistent > properties to anything they want without much effort and use their > preferred third-party parsers. While Cayenne would do all the DB-side > heavy lifting. The two parts are cleanly separated. Hello, I'm not familiar with the ValueObjectType, so what I'm writing here might be irrelevant, but at which point is the decision taken that the JSON column needs to be updated? Doing this in Hibernate using a CustomType, it is important that the mapped (deserialized) type has a correct equals method, and only if the value differs from the original value, then the serializer (e.g., Jackson) will be invoked and the resulting string (or jsonb) column will be updated in the database. It will likely be more efficient doing updates that way instead of always serializing and comparing the serialized value against the previous db state. But, as I said, please ignore this statement if it doesn't make sense in the context here. Greetings, Dirk
