MySQL JSON_OBJECT returning unparsable JSON - mysql

Question

I have a table of users similar to the statement below, (relevant fields included)
CREATE TABLE User (
ID INT NOT NULL AUTO_INCREMENT,
Username VARCHAR(30) NOT NULL,
IsActive BIT NOT NULL DEFAULT 1,
PRIMARY KEY (ID)
);
When I query the table with a simple SELECT statements, I get the fields back exactly as expected.
+----------------------------+
| ID | Username | IsActive |
+----+------------+----------+
| 42 | CoolGuy92 | 1 |
+----+------------+----------+
That's all well and good. If, though, I try to run the following query, and send its output to the browser for use, I get this error on the client side when trying to parse the return: Uncaught SyntaxError: Unexpected token in JSON at position X.
SELECT JSON_OBJECT(
"ID", Users.ID,
"Username", Users.Username,
"IsActive", Users.IsActive
)
FROM Users
What is causing this parsing error?

Answer 1

The parsing error occurs due to your IsActive column being the BIT data type. BIT columns have a charset and collation of binary, and are thusly stored as binary. An apparent value of 1 is actually stored as 0x01. During a normal query, MySQL will output the value of a BIT column using the schema's default character set, often treating it as an integer*. So for most cases, an apparent value of 1, becomes 0x31 and 0 becomes 0x30. This allows the returned values to be readable, and easily used as numbers or strings.
In the case of JSON_OBJECT though,
Strings produced by converting JSON values have a character set of utf8mb4 and a collation of utf8mb4_bin*
By making this conversion, the field's literal value is used and is output as \u0001. This is not escaped in any way, so when your browser attempts to parse the output, it fails when it reaches such a value.
To get around this, you can cast your BIT columns to another numeric datatype in your JSON_OBJECT call, or add 0 to it*.
SELECT JSON_OBJECT(
"ID", Users.ID,
"Username", Users.Username,
"IsActive", Users.IsActive + 0
)
FROM Users