Minimize Mysql Json output - mysql

Question

Mysql has a JSON_PRETTY() function to print human-readable JSON. I'm looking for the opposite functionality, to minimize JSON columns, getting rid of unnecessary whitespace, but haven't been able to find anything that does that. Is it possible to accomplish that with some combination of Mysql commands? I do need to do this in the SQL, not in application code.
INSERT INTO MY_TABLE(jsonPara) VALUES ('{"lamp": "hello world", "chair": "5"}');
select jsonPara, json_pretty(jsonPara) from MY_TABLE;
+-----------------------------------------+-------------------------------------------------+
|jsonPara |json_pretty(jsonPara) |
+-----------------------------------------+-------------------------------------------------+
|{"lamp": "hello world", "chair": "5"} |{ |
| |"lamp": "6", |
| |"chair": "5" |
| |} |
+-----------------------------------------+-------------------------------------------------+
I would like a result like {"lamp":"hello world","chair":"5"} (no spaces/new lines between keys and values and key/value pairs, array elements, etc.)

Answer 1

The best I can suggest is CAST(<expr> AS JSON). This reduces whitespace to a "normal" amount: one space after : and ,.
Here's your example document:
mysql> set #j = '{"lamp": "hello world", "chair": "5"}';
You know JSON_PRETTY() adds newlines and indentation:
mysql> select json_pretty(#j) as j;
+---------------------------------------------+
| j |
+---------------------------------------------+
| {
"lamp": "hello world",
"chair": "5"
} |
+---------------------------------------------+
Casting that expression back to JSON removes the extra whitespace:
mysql> select cast(json_pretty(#j) as json) as j;
+---------------------------------------+
| j |
+---------------------------------------+
| {"lamp": "hello world", "chair": "5"} |
+---------------------------------------+