[Ethereum] ethers.js – estimating gas limit

Gas Limit (maximum number of gas units required for the transaction to execute):

For this contract, I believe that you won't need more than 1 million gas units. You can put 2 million, I guess there's not much harm in that except for making your transaction take longer to execute. But you cannot put more than the block limit, which is typically around 8 million, depending on what network you're deploying to (mainnet, ropsten, your own private network, etc).

Value (amount of wei-ether passed within the transaction to the contract):

Since you don't have a payable fallback function in the contract, you cannot put anything other than 0, because the transaction will fail otherwise (in fact, that's probably the reason for your error).

Not sure why the default gas estimate from web3 -> metamask was so high, but I have gotten around this by using the estimated gas from estimateGas() + a buffer to manually set the gas sent in the depositAll transaction.

Here is the code:

const depositHelper = new web3.eth.Contract(
    DepositHelper.abi, // abi for DepositHelper contract
    '0x4681ae82f6f575da63b77a6735f44c13fdc2e4df'
);

// construct depositAll method parameters
const amount = 40; // 40 DAI
const weiAmount = window.web3.utils.toWei(amount, 'ether'); // convert to wei
const amounts = [weiAmount];
const vaults = ['0x3EE8bD22Df6605c6a7074c56Abb0f3Fc1FA6a069'];

depositHelper.methods
    .depositAll([amount], vaults)
    .estimateGas({ from: account, gas: 50000000 })
    .then(gasEstimate => {
        // not sure if there is a best practice for adding a gas buffer
        // so I just set it to 450k as a default
        return depositHelper.methods
            .depositAll(amounts, vaults).send({ from: account, gas: gasEstimate + 450000 })
        })
    .catch(error => {});