Rely on text internals to render json
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The output function lookup will be very hard because I am not sure how even to
find the type OID for `json` (not sure how to get a type from a Datum).
Under the hood, `json` (but not `jsonb`) is text. You can see one consequence
of this in the bodies of [`textout`] and [`json_out`]:
Datum
textout(PG_FUNCTION_ARGS)
{
Datum txt = PG_GETARG_DATUM(0);
PG_RETURN_CSTRING(TextDatumGetCString(txt));
}
Datum
json_out(PG_FUNCTION_ARGS)
{
/* we needn't detoast because text_to_cstring will handle that */
Datum txt = PG_GETARG_DATUM(0);
PG_RETURN_CSTRING(TextDatumGetCString(txt));
}
They are the same function. Clicking through the macros we get a cast and then
the conversion to a CString with `text_to_cstring`. So we don't need an ouput
function after all...
[`textout`]: http://doxygen.postgresql.org/varlena_8c_source.html#l00520
[`json_out`]: http://doxygen.postgresql.org/json_8c_source.html#l00245
solidsnack
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Feb 10, 2016
Rely on text internals to render `json`
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The output function lookup will be very hard because I am not sure how even to
find the type OID for
json(not sure how to get a type from a Datum).Under the hood,
json(but notjsonb) is text. You can see one consequenceof this in the bodies of
textoutandjson_out:They are the same function. Clicking through the macros we get a cast and then
the conversion to a CString with
text_to_cstring. So we don't need an ouputfunction after all.