From 8fca52bafc5b6b8dfc8d757c80a359202a56226c Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 3 Aug 2024 15:53:11 -0400 Subject: [PATCH v1 2/2] Make jsonb cast to text translate JSON null to SQL NULL. Previously, if the input was a JSON scalar null, you got the string 'null'. While that's not unreasonable in isolation, it's inconsistent with the behavior of the ->> operator. I think that (jsonb->'fld')::text should produce results identical to jsonb->>'fld', but up to now they disagree on this point. Some other jsonb processing functions such as jsonb_array_elements also translate JSON null to SQL NULL, and the preceding patch in this series applies that rule to other jsonb-to-scalar casts. This patch is incomplete: it only touches the behavior for casting to text. The pre-existing cast-via-I/O behavior applies to any string-category result type, so if we want consistency we'd better create explicit cast rules for varchar, bpchar, and name as well as text. (The regression tests added here demonstrate this inconsistency.) I've not done that, pending agreement on whether we want this behavioral change at all. Discussion: https://postgr.es/m/3851203.1722552717@sss.pgh.pa.us --- src/backend/utils/adt/jsonb.c | 23 +++++++++ src/include/catalog/pg_cast.dat | 5 +- src/include/catalog/pg_proc.dat | 3 ++ src/test/regress/expected/jsonb.out | 72 +++++++++++++++++++++++++++++ src/test/regress/sql/jsonb.sql | 12 +++++ 5 files changed, 114 insertions(+), 1 deletion(-) diff --git a/src/backend/utils/adt/jsonb.c b/src/backend/utils/adt/jsonb.c index ed054d5d42..c4e8db0d24 100644 --- a/src/backend/utils/adt/jsonb.c +++ b/src/backend/utils/adt/jsonb.c @@ -2222,6 +2222,29 @@ jsonb_float8(PG_FUNCTION_ARGS) PG_RETURN_DATUM(retValue); } +Datum +jsonb_text(PG_FUNCTION_ARGS) +{ + Jsonb *in = PG_GETARG_JSONB_P(0); + JsonbValue v; + StringInfoData jtext; + + /* Convert scalar null to SQL null */ + if (JsonbExtractScalar(&in->root, &v) && v.type == jbvNull) + { + PG_FREE_IF_COPY(in, 0); + PG_RETURN_NULL(); + } + + /* Every other case acts like jsonb_out() */ + initStringInfo(&jtext); + (void) JsonbToCString(&jtext, &in->root, VARSIZE(in)); + + PG_FREE_IF_COPY(in, 0); + + PG_RETURN_TEXT_P(cstring_to_text_with_len(jtext.data, jtext.len)); +} + /* * Convert jsonb to a C-string stripping quotes from scalar strings. */ diff --git a/src/include/catalog/pg_cast.dat b/src/include/catalog/pg_cast.dat index ca7b6d7191..bffe17ead0 100644 --- a/src/include/catalog/pg_cast.dat +++ b/src/include/catalog/pg_cast.dat @@ -512,7 +512,7 @@ { castsource => 'jsonb', casttarget => 'json', castfunc => '0', castcontext => 'a', castmethod => 'i' }, -# jsonb to numeric and bool types +# jsonb to various scalar types { castsource => 'jsonb', casttarget => 'bool', castfunc => 'bool(jsonb)', castcontext => 'e', castmethod => 'f' }, { castsource => 'jsonb', casttarget => 'numeric', castfunc => 'numeric(jsonb)', @@ -527,6 +527,9 @@ castcontext => 'e', castmethod => 'f' }, { castsource => 'jsonb', casttarget => 'float8', castfunc => 'float8(jsonb)', castcontext => 'e', castmethod => 'f' }, +# this cast replaces an implicit COERCEVIAIO cast, so must be assignment-level: +{ castsource => 'jsonb', casttarget => 'text', castfunc => 'text(jsonb)', + castcontext => 'a', castmethod => 'f' }, # range to multirange { castsource => 'int4range', casttarget => 'int4multirange', diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index d36f6001bb..c91824724c 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -4659,6 +4659,9 @@ { oid => '2580', descr => 'convert jsonb to float8', proname => 'float8', prorettype => 'float8', proargtypes => 'jsonb', prosrc => 'jsonb_float8' }, +{ oid => '8079', descr => 'convert jsonb to text', + proname => 'text', prorettype => 'text', proargtypes => 'jsonb', + prosrc => 'jsonb_text' }, # formatting { oid => '1770', descr => 'format timestamp with time zone to text', diff --git a/src/test/regress/expected/jsonb.out b/src/test/regress/expected/jsonb.out index c0bd0e76ae..dda3ee5b95 100644 --- a/src/test/regress/expected/jsonb.out +++ b/src/test/regress/expected/jsonb.out @@ -5763,3 +5763,75 @@ select '12345.0000000000000000000000000000000000000000000005'::jsonb::int8; 12345 (1 row) +select 'true'::jsonb::text; + text +------ + true +(1 row) + +select '1.0'::jsonb::text; + text +------ + 1.0 +(1 row) + +select '"hello"'::jsonb::text; + text +--------- + "hello" +(1 row) + +select 'null'::jsonb::text; + text +------ + +(1 row) + +select '[1.0]'::jsonb::text; + text +------- + [1.0] +(1 row) + +select '{"a": "b"}'::jsonb::text; + text +------------ + {"a": "b"} +(1 row) + +select 'true'::jsonb::varchar; + varchar +--------- + true +(1 row) + +select '1.0'::jsonb::varchar; + varchar +--------- + 1.0 +(1 row) + +select '"hello"'::jsonb::varchar; + varchar +--------- + "hello" +(1 row) + +select 'null'::jsonb::varchar; -- not the desired behavior + varchar +--------- + null +(1 row) + +select '[1.0]'::jsonb::varchar; + varchar +--------- + [1.0] +(1 row) + +select '{"a": "b"}'::jsonb::varchar; + varchar +------------ + {"a": "b"} +(1 row) + diff --git a/src/test/regress/sql/jsonb.sql b/src/test/regress/sql/jsonb.sql index 1bcafe8cfb..57240c4146 100644 --- a/src/test/regress/sql/jsonb.sql +++ b/src/test/regress/sql/jsonb.sql @@ -1569,3 +1569,15 @@ select '12345.0000000000000000000000000000000000000000000005'::jsonb::float8; select '12345.0000000000000000000000000000000000000000000005'::jsonb::int2; select '12345.0000000000000000000000000000000000000000000005'::jsonb::int4; select '12345.0000000000000000000000000000000000000000000005'::jsonb::int8; +select 'true'::jsonb::text; +select '1.0'::jsonb::text; +select '"hello"'::jsonb::text; +select 'null'::jsonb::text; +select '[1.0]'::jsonb::text; +select '{"a": "b"}'::jsonb::text; +select 'true'::jsonb::varchar; +select '1.0'::jsonb::varchar; +select '"hello"'::jsonb::varchar; +select 'null'::jsonb::varchar; -- not the desired behavior +select '[1.0]'::jsonb::varchar; +select '{"a": "b"}'::jsonb::varchar; -- 2.43.5