Check if a user-defined type already exists in PostgreSQL

Question

Say I have created some user-defined types in the DB,

i.e. CREATE TYPE abc ...

Is it then possible to determine if the user-defined type exists

Answer 1

A more generic solution

CREATE OR REPLACE FUNCTION create_type(name text, _type text) RETURNS 
integer AS $$
DECLARE v_exists INTEGER;

BEGIN
    SELECT into v_exists (SELECT 1 FROM pg_type WHERE typname = name);
    IF v_exists IS NULL THEN
            EXECUTE format('CREATE TYPE %I AS %s', name, _type);
    END IF;
    RETURN v_exists;
END;
$$ LANGUAGE plpgsql;

and then you can call it like this:

select create_type('lwm2m_instancetype', 'enum (''single'',''multiple'')');