Use u64 as PDA seed

Question

I want to initialize a PDA with a big number for seed, but findProgramAddress returns an error: Uncaught (in promise) TypeError: (intermediate value).toBuffer is not a function

import { BN } from "@project-serum/anchor";

async function getPDA(id) {
    return await web3.PublicKey.findProgramAddress(
        [Buffer.from("seed1"), new BN(id).toBuffer()],
        PROGRAM_ID
    );
}

How do I findProgramAddress with a big number as seed?

Thanks.

Answer 1

Well, finally I solved it using:

Js:

async function getPDA(id) {
    return await web3.PublicKey.findProgramAddress(
        [Buffer.from("seed1"), new BN(id).toArrayLike(Buffer, "be", 8)],
        PROGRAM_ID
    );
}

Rust:

...
    #[account(init, seeds = [b"seed1".as_ref(), data_pda.number.to_be_bytes().as_ref(), payer=payer, space = 50], bump)]
    new_pda: Account<'info, SomeStruct>,
    #[account(mut, seeds = [b"master_account".as_ref()], bump)]
    data_pda: Account<'info, Data>,
...

#[account]
#[derive(Default)]
pub struct Data{
    pub number: u64,
}