GraphQL : Error while adding computed fields

Question

I am trying to add a computed field to my graphql table "user" in schema "abc" using the hasura API but receiving the following error :

Saving computed field failed
in table "abc.user": in computed field "full_name": the computed field "full_name" 
cannot be added to table "abc.user" because the function "abc.fullname" is 
of type VOLATILE; cannot be added as a computed field

The function is added correctly :

    CREATE OR REPLACE FUNCTION abc.fullname(userrow abc.user)
    RETURNS TEXT AS $$
BEGIN
    SELECT userrow.first_name || ' ' || userrow.last_name;
END;
$$ LANGUAGE plpgsql;

I am able to select the function "fullname" from the dropdown but getting an error on adding computed field. Any guidance is appreciated. Thank you.

Answer 1

The error message is trying to tell you. You need to explicitly declare the function as immutable so it can be used in the definition of the computed column:

create or replace function abc.fullname(userrow abc.user)
returns text immutable as $$
begin
    select userrow.first_name || ' ' || userrow.last_name;
end;
$$ language plpgsql;