Inserting a COALESCE(NULL,default)

Question

I have tables that use UUIDs. I want to be able to insert a new row with or without a UUID as sometimes the client will generate the UUID other times it won\'t.

Each

Answer 1

Overload the gen_random_uuid function:

create or replace function gen_random_uuid()
returns uuid as $$
    select 'a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11'::uuid;
$$ language sql;


create or replace function gen_random_uuid(_id uuid)
returns uuid as $$
    select coalesce(_id, gen_random_uuid());
$$ language sql;

Create the table as usual:

create table if not exists person (
    id uuid default gen_random_uuid()
);

Call the gen_random_uuid function inside the create_person function:

create or replace function create_person(_id uuid)
returns boolean as $$
    insert into person (id) values (gen_random_uuid(_id))
    returning true;
$$ language sql;

Then all the insert variations will work:

insert into person (id) values (default);
select create_person(null);
select create_person('b1eebc99-9c0b-4ef8-bb6d-6bb9bd380a22'::uuid);