JSON_EXTRACT

Takes an expression containing a JSON document, a JSON pointer expression, and an expected data type parameter. If the key specified using the JSON pointer expression exists, and its type conforms with the expected data type parameter, JSON_EXTRACT returns the value of the data type specified. Otherwise, returns NULL.

Syntax

JSON_EXTRACT(<json>, '<json_pointer_expression>', '<expected_type>')

Parameter	Type	Description
`<json>`	TEXT	The JSON document from which the value is to be extracted.
`<json_pointer_expression>`	Literal string	A JSON pointer to the location of the array in the JSON. For more information, see JSON pointer expression syntax.
`<expected_type>`	Literal string	The expected data type of the key indicated by `<json_pointer_expression>`, such as `TEXT` or `INTEGER`. For more information, see supported type parameters.

Example

For the JSON document indicated by <json_common_example> below, see JSON common example. The Returns result is based on this example.

SELECT
    JSON_EXTRACT(< json_common_example >, '/value/dyid', 'INTEGER')

Returns: 987

SELECT
    JSON_EXTRACT(<json_common_example>, '/value/no_such_key', 'TEXT')

Returns: NULL

SELECT
    JSON_EXTRACT(<json_common_example>, '/value/uid', 'INTEGER')

Returns: NULL since the JSON type under that key is a string.

SELECT
    JSON_EXTRACT(<json_common_example>,'/value/keywords', 'ARRAY(TEXT)')

Returns: ["insanely","fast","analytics"]