Withdrawing Funds

Withdrawals are used in two scenarios:

1. The campaign does not reach its goal by the end time
2. The campaign succeeds and the recipient deposits yield funds back into the contract

The goal is not met

If the goal is not met, all contributors can invoke the withdraw() function. This will effectively burn their campaign tokens and transfer the full amount of their contribution to their address.

const txn = await campaignContract.withdraw();

Yield

When a campaign succeeds the recipient can transfer any amount of the denominated token back to the contract. Campaign token holders then have a balance proportional to their holdings. For example, if Alice contributed 1 ETH into a campaign which raised 10 ETH, she will have claim on 10% of all yielded funds. If the creator yields 1 ETH back to the contract, Alice will have 0.1 ETH available to withdraw.

This does not burn any campaign tokens, instead it tracks withdraw amounts for each account to prevent overdraft.

const txn = await campaignContract.withdraw();

Preflight Checks

It's a good idea to determine if an account can withdraw before invoking withdraw functions to save gas.

Here is an example function to check the withdrawable amount for a given campaign and account.

async function withdrawableAmount(contract: Contract, account: string) : Promise<bigint> {
  if(!(await contract.isWithdrawAllowed()) {
    return 0n;
  }
 
  const tokenBalance = await contract.balanceOf(account);
  if(tokenBalance == 0n) {
    return 0n;
  }
 
  if((await contract.state()) === 'FUNDED') {
    return contract.yieldBalanceOf(account);
  }
 
  return tokenBalance;
}