How to convert results of a group by into a json using POSTGRESQL?

Question

I have the following question: If I have this data in a table:

How could you get a result like this:

It would be the same for me if the result came in a json like this:

Thank you!

Answer 1

To get the aggregated JSON you can use jsonb_object_agg()

select users, jsonb_object_agg(day, polls)
from data
group by users;

Online example