Postgres get multiple rows into a single json object

Question

I have a users table with columns like id , name , email , etc. I want to retrieve information of some users in the following format in a single json object:

{
    "userId_1" : {"name" : "A", "email": "A@gmail.com"},
    "userId_2" : {"name" : "B", "email": "B@gmail.com"}
}

Wherein the users unique id is the key and a json containing his information is its corresponding value.

I am able to get this information in two separate rows using json_build_object but I would want it get it in a single row in the form of one single json object.

Answer 1

You can use json aggregation functions:

select jsonb_object_agg(id, to_jsonb(t) - 'id') res
from mytable t

jsonb_object_agg() aggregates key/value pairs into a single object. The key is the id of each row, and the values is a jsonb object made of all columns of the table except id .

Demo on DB Fiddle

Sample data:

id       | name | email      
:------- | :--- | :----------
userid_1 | A    | A@gmail.com
userid_2 | B    | B@gmail.com

Results:

| res                                                                                                    |
| :----------------------------------------------------------------------------------------------------- |
| {"userid_1": {"name": "A", "email": "A@gmail.com"}, "userid_2": {"name": "B", "email": "B@gmail.com"}} |

Answer 2

try -

select row_to_json(col) from T

link below might help https://hashrocket.com/blog/posts/faster-json-generation-with-postgresql

Answer 3

Try this:

SELECT json_object(array_agg(id), array_agg(json::text)) FROM ( SELECT id, json_build_object('name', name, 'email', email) as json FROM users_table ) some_alias_name

If your id is not of text type then you have to cast it to text too.