How can I create a new PDA everytime?

Question

So let's say I'm creating a notes app on-chain where an user can create any amount of notes it wants.

so i've an endpoint create_note and I need to create a note PDA everytime an user calls that endpoint, how can I do that? Every example i've seen so far relies on non-unique seeds e.g. signer pub key.

*I'm using Anchor

Answer 1

When creating a PDA you can number to each note to give it a unique PDA address and still have the signer key to ensure that the signer can only see their own notes. This number could be a user input or you could also implement a counter in the program. Having a number value here would also make it easier to index when displaying on an FE. It would look something like this:

#[derive(Accounts)]
#[instruction(number: u64, note: String)]
pub struct CreateEntry<'info> {
    #[account(
        init,
        seeds = [&number.to_le_bytes(), owner.key().as_ref()], 
        bump, 
        payer = owner, 
        space = 8 + 32 + 4 + 8 + 4 + note.len()
    )]
    pub note: Account<'info, NoteState>,
    #[account(mut)]
    pub owner: Signer<'info>,
    pub system_program: Program<'info, System>,
}