HeapTuple to JSON -- composite_to_json()?

Hi All,

I am working on a logical decoder and would like to convert a heap tuple to
JSON (a HeapTuple obtained from ReorderBufferChange). It is the moral
equivalent of tuple_to_stringinfo in test_decode.c:

http://doxygen.postgresql.org/test__decoding_8c.html#a3986a57a0308de0150ebd45f7734d464

It seems like the easiest and best thing to do is to rely on Postgres’s
native JSON serialization. A HeapTuple is not a Datum; but reading
heaptuple.c they seem to have a close relationship. Do arrays of Datum
become HeapTuple? Is a HeapTuple basically Datum sans type information?
What is the best way to convert a HeapTuple to a Datum?

Best Regards,

Jason Dusek
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