\n can't be posted to a MYSQL server - mysql

Question

I am trying to get, post and put JSON data to a MYSQL server (docker container) that uses utf8 as the charset. Within this JSON data are strings that should contain "\n". When the data is applied in my application these "\n" are causing linebreaks which is what I want.
But when I try to insert this into my database it throws an error: "ERROR 3140 (22032) at line x: "Invalid JSON text: "Invalid encoding in string.".
Solutions I found suggested adding additional backslashes (" '\' \n"). While this works for inserting, it doesn't allow for the linebreaks I wanted in my application. Is there some way around without changing the application ?
SQL Query:
INSERT INTO table (id, json) VALUES (1,'{"data": "name: ab \n cost: 5 $ | time: 1 s"}')

Answer 1

INSERT INTO table (id, json) VALUES (1,'{"data": "name: ab \n cost: 5 $ | time: 1 s"}')
\n is a escape sequence in SQL so you're sending an actual carriage return character rather than a backslash followed by letter n, which is what JSON mandates. It's more obvious with this other query:
mysql> select '{"data": "name: ab \n cost: 5 $ | time: 1 s"}' as test;
+----------------------------------------------+
| test |
+----------------------------------------------+
| {"data": "name: ab
cost: 5 $ | time: 1 s"} |
+----------------------------------------------+
1 row in set (0.00 sec)
To insert a literal \ in MySQL you need to escape with another \:
mysql> select 'one\\ntwo' as test;
+----------+
| test |
+----------+
| one\ntwo |
+----------+
1 row in set (0.00 sec)
Please note this is only an issue when you type literal strings in your code. It won't affect data coming from other sources (e.g. HTML forms or databases) unless you fail to process it somewhere (e.g. by injecting it in raw SQL rather than using prepared statements).