Add json_strip_nulls and jsonb_strip_nulls functions.

The functions remove object fields, including in nested objects, that
have null as a value. In certain cases this can lead to considerably
smaller datums, with no loss of semantic information.

Andrew Dunstan, reviewed by Pavel Stehule.

1 files changed, 20 insertions, 0 deletions

diff --git a/src/test/regress/sql/json.sql b/src/test/regress/sql/json.sql
index c9801321e09..36a6674ff91 100644
--- a/src/test/regress/sql/json.sql
+++ b/src/test/regress/sql/json.sql
@@ -509,3 +509,23 @@ select * from json_to_recordset('[{"a":1,"b":"foo","d":false},{"a":2,"b":"bar","
 
 select * from json_to_recordset('[{"a":1,"b":{"d":"foo"},"c":true},{"a":2,"c":false,"b":{"d":"bar"}}]')
     as x(a int, b json, c boolean);
+
+
+-- json_strip_nulls
+
+select json_strip_nulls(null);
+
+select json_strip_nulls('1');
+
+select json_strip_nulls('"a string"');
+
+select json_strip_nulls('null');
+
+select json_strip_nulls('[1,2,null,3,4]');
+
+select json_strip_nulls('{"a":1,"b":null,"c":[2,null,3],"d":{"e":4,"f":null}}');
+
+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": {} }');