How to get data account from an instruction?

Question

Hi i have a UserAccount which is used to hold the data of the user and is created with a instruction called sign_up , and also i have a setup_game instruction and in there I want to check that is there a user registered with the given Pubkey. In TS tests to do that i use :

const account = await program.account.userAccount.fetch(
            secondUser.publicKey
        ); 

So this gives the user_account of that Pubkey . And my Rust code so far :

pub fn setup_game(ctx: Context<SetupGame>, player_two: Pubkey) -> Result<()> {
    ctx.accounts
        .game
        .start([ctx.accounts.player_one.key(), player_two])
}

Answer 1

On solana, for you to read/write to an account, it needs to be passed as an account to the instruction.

So if you want to read the account that belongs to player_two, you'll need to pass it as an account to the SetupGame instruction.

So you'll have access to the account info of ctx.accounts.player_two if its initialized