Allow json{b}_strip_nulls to remove null array elements

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

src/test/regress/expected/json.out

@@ -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                                

src/test/regress/expected/jsonb.out

@@ -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        
 ----------------------------

src/test/regress/sql/json.sql

@@ -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);
 

src/test/regress/sql/jsonb.sql

@@ -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]');