I want to do something like this in PostgreSQL.

I tried this:

    CREATE or replace FUNCTION create_patient(_name text, _email text, _phone text, _password text, _field1 text, _field2 text, _field3 timestamp, _field4 text, OUT _pid integer, OUT _id integer) RETURNS record AS $$
DECLARE
    _id integer;
    _type text;
    _pid integer;
BEGIN
    _type := 'patient'; 
    INSERT into patients (name, email, phone, field1, field2, field3) values (_name, _email, _phone, _field1, _field2, _field3) RETURNING id into _pid;
    INSERT into users (username, password, type, pid, phone, language) values (_email, _password, _type, _pid, _phone, _field4) RETURNING id into _id;    
END;
$$ LANGUAGE plpgsql;

But there are a lot of instances where I would not want to specify some of field1/field2/field3/field4 and want the unspecified fields to use the default value in the table. Currently that is not possible, because to call this function I need to specify all fields.

TLDR; Is there a simple way to create a wrapper procedure for INSERT in PL/pgSQL where I can specify which fields I want to insert?