get_json_string,get_json_object

Description

Analyzes and gets strings from the specified path (json_path) in a JSON string. If the format of json_string or json_path is wrong or if no matching value is found, this function will return NULL.

The alias is get_json_object.

Syntax

VARCHAR get_json_string(VARCHAR json_str, VARCHAR json_path)

Parameters

• json_str: the JSON string. Supported data type is VARCHAR.
• json_path: the JSON path. Supported data type is VARCHAR. json_path starts with $ and uses . as the path separator. [ ] is used as the array subscripts which starts from 0. For example, $."my.key"[1] indicates to obtain the second value form element my.key.

Return value

Returns a value of the VARCHAR type. If no matching object is found, NULL is returned.

Examples

Example 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                                                |
+---------------------------------------------------+

Example 2: Get the value whose key is a from the first element.

MySQL > SELECT get_json_object('[{"a":"123", "b": "456"},{"a":"23", "b": "56"}]', '$[0].a');
+------------------------------------------------------------------------------+
| get_json_object('[{"a":"123", "b": "456"},{"a":"23", "b": "56"}]', '$[0].a') |
+------------------------------------------------------------------------------+
| 123                                                                          |
+------------------------------------------------------------------------------+

Example 3: 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                                                                           |
+------------------------------------------------------------------------------+

Example 4: 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                                                                    |
+-----------------------------------------------------------------------+

Example 5: 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