get_json_string

Description

This function analyzes and gets the strings from a specified path in json string.

json_path must start with $ and use . as the path separator.

If the path includes ., it could be circled by " and ".

[ ] is used as the array subscripts which start from 0.

Content in the path should not contain " , [ and ].

If the format of json_string or json_path is wrong, this function will return NULL.

Syntax

VARCHAR get_json_string(VARCHAR json_str, VARCHAR json_path)

Examples

1. Get the value whose key is "k1"

   MySQL > SELECT get_json_string('{"k1":"v1", "k2":"v2"}', "$.k1");
   +---------------------------------------------------+
   | get_json_string('{"k1":"v1", "k2":"v2"}', '$.k1') |
   +---------------------------------------------------+
   | v1                                                |
   +---------------------------------------------------+

2. Get the second element in the array whose key is "my.key"

   MySQL > SELECT get_json_string('{"k1":"v1", "my.key":["e1", "e2", "e3"]}', '$."my.key"[1]');
   +------------------------------------------------------------------------------+
   | get_json_string('{"k1":"v1", "my.key":["e1", "e2", "e3"]}', '$."my.key"[1]') |
   +------------------------------------------------------------------------------+
   | e2                                                                           |
   +------------------------------------------------------------------------------+

3. Get the first element in the array whose path is k1.key -> k2.

   MySQL > SELECT get_json_string('{"k1.key":{"k2":["v1", "v2"]}}', '$."k1.key".k2[0]');
   +-----------------------------------------------------------------------+
   | get_json_string('{"k1.key":{"k2":["v1", "v2"]}}', '$."k1.key".k2[0]') |
   +-----------------------------------------------------------------------+
   | v1                                                                    |
   +-----------------------------------------------------------------------+

4. Get all values whose key is "k1" from the array.

   MySQL > SELECT get_json_string('[{"k1":"v1"}, {"k2":"v2"}, {"k1":"v3"}, {"k1":"v4"}]', '$.k1');
   +---------------------------------------------------------------------------------+
   | get_json_string('[{"k1":"v1"}, {"k2":"v2"}, {"k1":"v3"}, {"k1":"v4"}]', '$.k1') |
   +---------------------------------------------------------------------------------+
   | ["v1","v3","v4"]                                                                |
   +---------------------------------------------------------------------------------+

keyword

GET_JSON_STRING,GET,JSON,STRING