How can we generate random values in Scrypto?

Question

How can we generate random numbers in Scrypto if floating point libraries are not allowed be used? I want to be able to generate unique IDs for NFTs.

Answer 1

There are 2 ways to solve this:

1. Self managed - if the data structure is a Vec, we can use vec.len() + 1 as the generated ID, making things more trivial.
2. Generated Uuid - Scrypto provides Runtime::generate_uuid which is a generated number format in Uuid which should guarantee uniqueness

We can also generate values given a max range:

fn get_random(end: usize) -> usize {
    let num = Runtime::generate_uuid();
    (num % end as u128) as usize
}

// prints number between 0 - 5
info!("{}", get_random(5));

Answer 2

You can generate a pseudo random NFT id using the built-in NonFungibleId::random() method.

let new_nft_id: NonFungibleId = NonFungibleId::random();

Reference: https://radixdlt.github.io/radixdlt-scrypto/scrypto/resource/struct.NonFungibleId.html