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Allow json{b}_strip_nulls to remove null array elements

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An additional paramater ("strip_in_arrays") is added to these functions.
It defaults to false. If true, then null array elements are removed as
well as null valued object fields. JSON that just consists of a single
null is not affected.

Author: Florents Tselai <florents.tselai@gmail.com>

Discussion: https://postgr.es/m/4BCECCD5-4F40-4313-9E98-9E16BEB0B01D@gmail.com
pull/207/head
Andrew Dunstan 6 months ago
parent 5ead85fbc8
commit 4603903d29
8 changed files with 190 additions and 9 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 17
      doc/src/sgml/func.sgml
  2. 14
      src/backend/catalog/system_functions.sql
  3. 27
      src/backend/utils/adt/jsonfuncs.c
  4. 4
      src/include/catalog/pg_proc.dat
  5. 50
      src/test/regress/expected/json.out
  6. 50
      src/test/regress/expected/jsonb.out
  7. 19
      src/test/regress/sql/json.sql
  8. 18
      src/test/regress/sql/jsonb.sql

17
doc/src/sgml/func.sgml
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@ -17345,25 +17345,32 @@ ERROR: value too long for type character(2)
<indexterm>
<primary>json_strip_nulls</primary>
</indexterm>
<function>json_strip_nulls</function> ( <type>json</type> )
<function>json_strip_nulls</function> ( <parameter>target</parameter> <type>jsonb</type>, <optional>,<parameter>strip_in_arrays</parameter> <type>boolean</type> </optional> )
<returnvalue>json</returnvalue>
</para>
<para role="func_signature">
<indexterm>
<primary>jsonb_strip_nulls</primary>
</indexterm>
<function>jsonb_strip_nulls</function> ( <type>jsonb</type> )
<function>jsonb_strip_nulls</function> ( <parameter>target</parameter> <type>jsonb</type>, <optional>,<parameter>strip_in_arrays</parameter> <type>boolean</type> </optional> )
<returnvalue>jsonb</returnvalue>
</para>
<para>
Deletes all object fields that have null values from the given JSON
value, recursively. Null values that are not object fields are
untouched.
value, recursively.
If <parameter>strip_in_arrays</parameter> is true (the default is false),
null array elements are also stripped.
Otherwise they are not stripped. Bare null values are never stripped.
</para>
<para>
<literal>json_strip_nulls('[{"f1":1, "f2":null}, 2, null, 3]')</literal>
<returnvalue>[{"f1":1},2,null,3]</returnvalue>
</para></entry>
</para>
<para>
<literal>jsonb_strip_nulls('[1,2,null,3,4]', true);</literal>
<returnvalue>[1,2,3,4]</returnvalue>
</para>
</entry>
</row>
<row>

14
src/backend/catalog/system_functions.sql
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@ -607,6 +607,20 @@ LANGUAGE INTERNAL
STRICT STABLE PARALLEL SAFE
AS 'jsonb_path_query_first_tz';
CREATE OR REPLACE FUNCTION
jsonb_strip_nulls(target jsonb, strip_in_arrays boolean DEFAULT false)
RETURNS jsonb
LANGUAGE INTERNAL
STRICT STABLE PARALLEL SAFE
AS 'jsonb_strip_nulls';
CREATE OR REPLACE FUNCTION
json_strip_nulls(target json, strip_in_arrays boolean DEFAULT false)
RETURNS json
LANGUAGE INTERNAL
STRICT STABLE PARALLEL SAFE
AS 'json_strip_nulls';
-- default normalization form is NFC, per SQL standard
CREATE OR REPLACE FUNCTION
"normalize"(text, text DEFAULT 'NFC')

27
src/backend/utils/adt/jsonfuncs.c
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@ -286,6 +286,7 @@ typedef struct StripnullState
JsonLexContext *lex;
StringInfo strval;
bool skip_next_null;
bool strip_in_arrays;
} StripnullState;
/* structure for generalized json/jsonb value passing */
@ -4460,8 +4461,19 @@ sn_array_element_start(void *state, bool isnull)
{
StripnullState *_state = (StripnullState *) state;
if (_state->strval->data[_state->strval->len - 1] != '[')
/* If strip_in_arrays is enabled and this is a null, mark it for skipping */
if (isnull && _state->strip_in_arrays)
{
_state->skip_next_null = true;
return JSON_SUCCESS;
}
/* Only add a comma if this is not the first valid element */
if (_state->strval->len > 0 &&
_state->strval->data[_state->strval->len - 1] != '[')
{
appendStringInfoCharMacro(_state->strval, ',');
}
return JSON_SUCCESS;
}
@ -4493,6 +4505,7 @@ Datum
json_strip_nulls(PG_FUNCTION_ARGS)
{
text *json = PG_GETARG_TEXT_PP(0);
bool strip_in_arrays = PG_NARGS() == 2 ? PG_GETARG_BOOL(1) : false;
StripnullState *state;
JsonLexContext lex;
JsonSemAction *sem;
@ -4503,6 +4516,7 @@ json_strip_nulls(PG_FUNCTION_ARGS)
state->lex = makeJsonLexContext(&lex, json, true);
state->strval = makeStringInfo();
state->skip_next_null = false;
state->strip_in_arrays = strip_in_arrays;
sem->semstate = state;
sem->object_start = sn_object_start;
@ -4520,12 +4534,13 @@ json_strip_nulls(PG_FUNCTION_ARGS)
}
/*
* SQL function jsonb_strip_nulls(jsonb) -> jsonb
* SQL function jsonb_strip_nulls(jsonb, bool) -> jsonb
*/
Datum
jsonb_strip_nulls(PG_FUNCTION_ARGS)
{
Jsonb *jb = PG_GETARG_JSONB_P(0);
bool strip_in_arrays = false;
JsonbIterator *it;
JsonbParseState *parseState = NULL;
JsonbValue *res = NULL;
@ -4534,6 +4549,9 @@ jsonb_strip_nulls(PG_FUNCTION_ARGS)
JsonbIteratorToken type;
bool last_was_key = false;
if (PG_NARGS() == 2)
strip_in_arrays = PG_GETARG_BOOL(1);
if (JB_ROOT_IS_SCALAR(jb))
PG_RETURN_POINTER(jb);
@ -4564,6 +4582,11 @@ jsonb_strip_nulls(PG_FUNCTION_ARGS)
(void) pushJsonbValue(&parseState, WJB_KEY, &k);
}
/* if strip_in_arrays is set, also skip null array elements */
if (strip_in_arrays)
if (type == WJB_ELEM && v.type == jbvNull)
continue;
if (type == WJB_VALUE || type == WJB_ELEM)
res = pushJsonbValue(&parseState, type, &v);
else

4
src/include/catalog/pg_proc.dat
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@ -9269,7 +9269,7 @@
proname => 'to_json', provolatile => 's', prorettype => 'json',
proargtypes => 'anyelement', prosrc => 'to_json' },
{ oid => '3261', descr => 'remove object fields with null values from json',
proname => 'json_strip_nulls', prorettype => 'json', proargtypes => 'json',
proname => 'json_strip_nulls', prorettype => 'json', proargtypes => 'json bool',
prosrc => 'json_strip_nulls' },
{ oid => '3947',
@ -10205,7 +10205,7 @@
prorettype => 'jsonb', proargtypes => '',
prosrc => 'jsonb_build_object_noargs' },
{ oid => '3262', descr => 'remove object fields with null values from jsonb',
proname => 'jsonb_strip_nulls', prorettype => 'jsonb', proargtypes => 'jsonb',
proname => 'jsonb_strip_nulls', prorettype => 'jsonb', proargtypes => 'jsonb bool',
prosrc => 'jsonb_strip_nulls' },
{ oid => '3478',

50
src/test/regress/expected/json.out
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@ -2504,6 +2504,56 @@ select json_strip_nulls('{"a": {"b": null, "c": null}, "d": {} }');
{"a":{},"d":{}}
(1 row)
-- json_strip_nulls (strip_in_arrays=true)
select json_strip_nulls(null, true);
json_strip_nulls
------------------
(1 row)
select json_strip_nulls('1', true);
json_strip_nulls
------------------
1
(1 row)
select json_strip_nulls('"a string"', true);
json_strip_nulls
------------------
"a string"
(1 row)
select json_strip_nulls('null', true);
json_strip_nulls
------------------
null
(1 row)
select json_strip_nulls('[1,2,null,3,4]', true);
json_strip_nulls
------------------
[1,2,3,4]
(1 row)
select json_strip_nulls('{"a":1,"b":null,"c":[2,null,3],"d":{"e":4,"f":null}}', true);
json_strip_nulls
-------------------------------
{"a":1,"c":[2,3],"d":{"e":4}}
(1 row)
select json_strip_nulls('[1,{"a":1,"b":null,"c":2},3]', true);
json_strip_nulls
---------------------
[1,{"a":1,"c":2},3]
(1 row)
-- an empty object is not null and should not be stripped
select json_strip_nulls('{"a": {"b": null, "c": null}, "d": {} }', true);
json_strip_nulls
------------------
{"a":{},"d":{}}
(1 row)
-- json to tsvector
select to_tsvector('{"a": "aaa bbb ddd ccc", "b": ["eee fff ggg"], "c": {"d": "hhh iii"}}'::json);
to_tsvector

50
src/test/regress/expected/jsonb.out
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@ -4153,6 +4153,56 @@ select jsonb_strip_nulls('{"a": {"b": null, "c": null}, "d": {} }');
{"a": {}, "d": {}}
(1 row)
-- jsonb_strip_nulls (strip_in_arrays=true)
select jsonb_strip_nulls(null, true);
jsonb_strip_nulls
-------------------
(1 row)
select jsonb_strip_nulls('1', true);
jsonb_strip_nulls
-------------------
1
(1 row)
select jsonb_strip_nulls('"a string"', true);
jsonb_strip_nulls
-------------------
"a string"
(1 row)
select jsonb_strip_nulls('null', true);
jsonb_strip_nulls
-------------------
null
(1 row)
select jsonb_strip_nulls('[1,2,null,3,4]', true);
jsonb_strip_nulls
-------------------
[1, 2, 3, 4]
(1 row)
select jsonb_strip_nulls('{"a":1,"b":null,"c":[2,null,3],"d":{"e":4,"f":null}}', true);
jsonb_strip_nulls
--------------------------------------
{"a": 1, "c": [2, 3], "d": {"e": 4}}
(1 row)
select jsonb_strip_nulls('[1,{"a":1,"b":null,"c":2},3]', true);
jsonb_strip_nulls
--------------------------
[1, {"a": 1, "c": 2}, 3]
(1 row)
-- an empty object is not null and should not be stripped
select jsonb_strip_nulls('{"a": {"b": null, "c": null}, "d": {} }', true);
jsonb_strip_nulls
--------------------
{"a": {}, "d": {}}
(1 row)
select jsonb_pretty('{"a": "test", "b": [1, 2, 3], "c": "test3", "d":{"dd": "test4", "dd2":{"ddd": "test5"}}}');
jsonb_pretty
----------------------------

19
src/test/regress/sql/json.sql
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@ -814,6 +814,25 @@ select json_strip_nulls('[1,{"a":1,"b":null,"c":2},3]');
-- an empty object is not null and should not be stripped
select json_strip_nulls('{"a": {"b": null, "c": null}, "d": {} }');
-- json_strip_nulls (strip_in_arrays=true)
select json_strip_nulls(null, true);
select json_strip_nulls('1', true);
select json_strip_nulls('"a string"', true);
select json_strip_nulls('null', true);
select json_strip_nulls('[1,2,null,3,4]', true);
select json_strip_nulls('{"a":1,"b":null,"c":[2,null,3],"d":{"e":4,"f":null}}', true);
select json_strip_nulls('[1,{"a":1,"b":null,"c":2},3]', true);
-- an empty object is not null and should not be stripped
select json_strip_nulls('{"a": {"b": null, "c": null}, "d": {} }', true);
-- json to tsvector
select to_tsvector('{"a": "aaa bbb ddd ccc", "b": ["eee fff ggg"], "c": {"d": "hhh iii"}}'::json);

18
src/test/regress/sql/jsonb.sql
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@ -1102,6 +1102,24 @@ select jsonb_strip_nulls('[1,{"a":1,"b":null,"c":2},3]');
-- an empty object is not null and should not be stripped
select jsonb_strip_nulls('{"a": {"b": null, "c": null}, "d": {} }');
-- jsonb_strip_nulls (strip_in_arrays=true)
select jsonb_strip_nulls(null, true);
select jsonb_strip_nulls('1', true);
select jsonb_strip_nulls('"a string"', true);
select jsonb_strip_nulls('null', true);
select jsonb_strip_nulls('[1,2,null,3,4]', true);
select jsonb_strip_nulls('{"a":1,"b":null,"c":[2,null,3],"d":{"e":4,"f":null}}', true);
select jsonb_strip_nulls('[1,{"a":1,"b":null,"c":2},3]', true);
-- an empty object is not null and should not be stripped
select jsonb_strip_nulls('{"a": {"b": null, "c": null}, "d": {} }', true);
select jsonb_pretty('{"a": "test", "b": [1, 2, 3], "c": "test3", "d":{"dd": "test4", "dd2":{"ddd": "test5"}}}');
select jsonb_pretty('[{"f1":1,"f2":null},2,null,[[{"x":true},6,7],8],3]');

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