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PostgreSQL jsonb_path_exists() Function

Summary: in this tutorial, you will learn how to use the PostgreSQL jsonb_path_exists() function to check if a JSON path returns any item for a specified JSON document.

Introduction to the PostgreSQL jsonb_path_exists() function​

The jsonb_path_exists() function allows you to check if a JSON path matches any element in a JSON document.

Here’s the syntax of the jsonb_path_exists() function:

jsonb_path_exists(jsonb_data, json_path)

In this syntax:

  • jsonb_data is a JSON document where you want to check for a JSON path.
  • json_path is the path that you want to check.

The jsonb_path_exists() function returns true if the json_path returns any elements in the jsonb_data document or false otherwise.

PostgreSQL jsonb_path_exists() function example​

Let’s take some examples of using the jsonb_path_exists() function.

Setting up a sample table​

First, create a new table called products that store product information:

CREATE TABLE products (
    id SERIAL PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    attributes JSONB
);

The products table has the attributes column whose data type is JSONB.

Second, insert rows into the products table:

INSERT INTO products (name, attributes)
VALUES
    ('Laptop', '{"brand": "Dell", "price": 1200, "specs": {"cpu": "Intel i7", "ram": "16GB"}}'),
    ('Smartphone', '{"brand": "Samsung", "price": 800, "specs": {"os": "Android", "storage": "128GB"}}')
RETURNING *;

Output:

 id |    name    |                                     attributes

----+------------+------------------------------------------------------------------------------------
  1 | Laptop     | {"brand": "Dell", "price": 1200, "specs": {"cpu": "Intel i7", "ram": "16GB"}}
  2 | Smartphone | {"brand": "Samsung", "price": 800, "specs": {"os": "Android", "storage": "128GB"}}
(2 rows)

1) Basic jsonb_path_exists() function example​

The following example uses the jsonb_path_exists() function to check whether the CPU specification exists for any product:

SELECT name,
       jsonb_path_exists(attributes, '$.specs.cpu') AS cpu_exists
FROM products;

Output:

    name    | cpu_exists
------------+------------
 Laptop     | t
 Smartphone | f
(2 rows)

2) Using the jsonb_path_exists() function in the WHERE clause​

The following example uses the jsonb_path_exists() function with the jsonb_path_query() function to retrieve the CPU specification of any products that have CPU spec:

SELECT jsonb_path_query(attributes, '$.specs.cpu') AS cpu
FROM products
WHERE jsonb_path_exists(attributes, '$.specs.cpu');

Output:

    cpu
------------
 "Intel i7"
(1 row)

Summary​

  • Use the jsonb_path_exists() function to check the existence of JSON Path expressions within JSONB data