Introduction to the PostgreSQL jsonb_each() function

Thejsonb_each() function allows you to expand a top-levelJSON object of a JSONB value into a set of key/value pairs. The keys are text and values are JSON values.

Here’s the syntax of thejsonb_each() function:

jsonb_each(json_object)

In this syntax:

• json_object is the JSON object that you want to expand the key/value pairs.

The function returns a set of records where each record consists of two fields key of typetext and value of theJSONB.

If thejson_object is not a JSON object, the function will issue an error. In case thejson_object is null, the function returns an empty set.

PostgreSQL jsonb_each() function examples

Let’s explore some examples of using thejsonb_each() function.

1) Basic PostgreSQL jsonb_each() function example

The following example uses thejsonb_each function to expand the key/value pair of a JSON object:

SELECT  *FROM  jsonb_each(    '{"name": "John", "age": 30, "city": "New York"}'  );

Output:

key  |   value------+------------ age  | 30 city | "New York" name | "John"(3 rows)

If you want to retrieve a particular key, you can filter the key in theWHERE clause.

For example, the following statement returns the name and age of the object:

SELECT  *FROM  jsonb_each(    '{"name": "John", "age": 30, "city": "New York"}'  )WHERE  key in ('name','age');

Output:

key  | value------+-------- age  | 30 name | "John"(2 rows)

2) Using the jsonb_each() function with table data

First,create a new table calledlinks:

CREATE TABLE links (    idSERIAL PRIMARY KEY,    hrefTEXT NOT NULL,    attributes JSONB);

In thelinks table, theattributes column has the type ofJSONB that stores various attributes of a link.

Second,insert some rows into thelinks table:

INSERT INTO links (href, attributes)VALUES    ('https://example.com','{"rel": "stylesheet", "type": "text/css", "media": "screen"}'),    ('https://example.org','{"rel": "icon", "type": "image/x-icon"}'),    ('https://example.net','{"rel": "alternate", "type": "application/rss+xml", "title": "RSS Feed"}');

Third, expand the key/value pairs of the objects inattributes column into a set of key/value pairs using thejsonb_each() function:

SELECT  href,  key,  valueFROM  links,  jsonb_each(attributes);

Output:

href         |  key  |         value---------------------+-------+----------------------- https://example.com | rel   | "stylesheet" https://example.com | type  | "text/css" https://example.com | media | "screen" https://example.org | rel   | "icon" https://example.org | type  | "image/x-icon" https://example.net | rel   | "alternate" https://example.net | type  | "application/rss+xml" https://example.net | title | "RSS Feed"(8 rows)

Summary

• Use thejsonb_each() function to expand a JSON object into a set of key/value pairs.

Last updated onFebruary 24, 2024

On this page

• Introduction to the PostgreSQL jsonb_each() function
• PostgreSQL jsonb_each() function examples
• Summary