Extracts the expression of the specified path from a JSON string.
Limits
This function is supported only in Realtime Compute for Apache Flink that uses Ververica Runtime (VVR) 3.0.0 or later.
Syntax
VARCHAR JSON_VALUE(VARCHAR content, VARCHAR path)Input parameters
Parameter | Data type | Description |
content | VARCHAR | The JSON object that you want to parse. |
path | VARCHAR | The expression of the specified path. You must use single quotation marks (') in a custom path. Example: The following symbols are supported in a path:
|
If the input parameters contain invalid JSON or NULL values, NULL is returned.
Example
Test data
Table 1 T1 id(INT)
json(VARCHAR)
path1(VARCHAR)
1
[10, 20, [30, 40]]
$[2][*]
2
{"aaa":"bbb","ccc":{"ddd":"eee","fff":"ggg","hhh":["h0","h1","h2"]},"iii":"jjj"}
$.ccc.hhh[*]
3
{"aaa":"bbb","ccc":{"ddd":"eee","fff":"ggg","hhh":["h0","h1","h2"]},"iii":"jjj"}
$.ccc.hhh[1]
4
[10, 20, [30, 40]]
NULL
5
NULL
$[2][*]
6
"{xx]"
"$[2][*]"
Test statement
SELECT id, JSON_VALUE(json, path1) AS `value` FROM T1;Test result
id (INT)
value (VARCHAR)
1
[30,40]
2
["h0","h1","h2"]
3
h1
4
NULL
5
NULL
6
NULL
References
For more information about the built-in functions that are supported by fully managed Flink, see Supported functions.
For more information about user-defined functions (UDFs), see UDFs and Manage UDFs.