JSON output in Postgresql

Question

I hope I am not missing something very obvious here,
I want to get JSON output from a postgres function (I imagine many other had already needed this) and I\'d be happy

Answer 1

There is built-in support for JSON since PostgreSQL 9.2 and it has increased with many other features in more recent versions(For example: JSON functions in PostgreSQL 0.4).

Specially the row_to_json converts a record into a JSON object and the array_to_json turns arrays into JSON arrays.

For example, both functions can be combined to easily turn the results of a SELECT query into JSON:

SELECT array_to_json(array_agg(row_to_json(t))) FROM 
    (SELECT col1, col2, col3 FROM example_table) t

Answer 2

On the server install:
sudo apt-get install postgresql-plpython-9.4

Then on your Postgres server:

CREATE EXTENSION IF NOT EXISTS plpythonu;
CREATE LANGUAGE plpythonu;

CREATE OR REPLACE FUNCTION prettyprint_json(data text)
 RETURNS json
 AS $$
    import json
    return json.dumps(json.loads(data), indent=4)
 $$ LANGUAGE plpythonu;

Answer 3

Use record_to_json(...) from 9.2, now available backported to 9.1.

Answer 4

The postgresql plpython plugin certainly lets you do this using the python json library.

You can do something like this:

CREATE OR REPLACE FUNCTION myschema.tojsonfunc()
AS $$    

   import json;
   jsonStr = json.dumps(myrecord)

$$ LANGUAGE plpythonu;