In MariaDB, JSON_VALID() is a built-in function that allows you to check whether or not a value is a valid JSON document.

You pass the value as an argument, and JSON_VALID() returns 1 if it’s a valid JSON document, and 0 if not.

Syntax

The syntax goes like this:

JSON_VALID(value)

Example

Here’s an example to demonstrate.

SELECT JSON_VALID('{ "product" : "Cup" }');

Result:

+-------------------------------------+
| JSON_VALID('{ "product" : "Cup" }') |
+-------------------------------------+
|                                   1 |
+-------------------------------------+

In this case, the argument is a valid JSON document.

Here’s what happens if we remove part of the document:

SELECT JSON_VALID('{ "product" }');

Result:

+-----------------------------+
| JSON_VALID('{ "product" }') |
+-----------------------------+
|                           0 |
+-----------------------------+

Now it’s not a valid JSON document.

Arrays

Arrays are considered a valid JSON document.

Example:

SELECT JSON_VALID('[ 1, 2, 3 ]');

Result:

+---------------------------+
| JSON_VALID('[ 1, 2, 3 ]') |
+---------------------------+
|                         1 |
+---------------------------+

Null Arguments

If the argument is NULL, the result is NULL:

SELECT JSON_VALID(null);

Result:

+------------------+
| JSON_VALID(null) |
+------------------+
|             NULL |
+------------------+

Incorrect Parameter Count

Calling JSON_VALID() without an argument results in an error:

SELECT JSON_VALID();

Result:

ERROR 1582 (42000): Incorrect parameter count in the call to native function 'JSON_VALID'

It’s the same when you provide too many arguments:

SELECT JSON_VALID('a', 'b');

Result:

ERROR 1582 (42000): Incorrect parameter count in the call to native function 'JSON_VALID'