JSON_EXTRACT_PATH

In this article, you will learn about the JSON_EXTRACT_PATH() function to extract the JSON sub-object.

Overview

JSON_EXTRACT_PATH() function extracts JSON nested value from a specified path.

Syntax

The syntax of the JSON_EXTRACT_PATH() function can be seen below. 

JSON_EXTRACT_PATH(from_json JSON, path TEXT[])

• from_json: the JSON value from which to extract.
• path: the path to extract.

Another Option

Besides the syntax above, Oxla provides and supports the use of operators in queries. See the syntax below:

SELECT 'from_json'::JSON -> 'path';

• from_json: the JSON value from which to extract.
• ::JSON: a symbol that casts the string literal to a JSON type.
• path: key of the field that we want to extract.

Examples

These examples display how JSON_EXTRACT_PATH() extracts the "oxla" JSON sub-object from the specified path.

1) Use the below query:

SELECT JSON_EXTRACT_PATH('{"f2":{"f3":1},"f4":{"f5":99,"f6":"oxla"}}', 'f4', 'f6');

or

SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"oxla"}}'::JSON -> 'f4' -> 'f6';

The query above will return the following result.

+---------+
| f       |
+---------+
| "oxla"  |
+---------+

2) Run the query below:

SELECT
    JSON_EXTRACT_PATH('{"a": 1, "b": {"x": "subtract", "y": "plus"}}', 'b', 'x') AS "bx",
    JSON_EXTRACT_PATH('{"a": 1, "b": {"x": "multiply", "y": "divide"}}', 'b', 'y') AS "by";

You will get the following output:

+---------------+-------------+
| bx            | by          |
+---------------+-------------+
| "subtract"    | "divide"    |
+---------------+-------------+