批准是否需要时间来确认，以及如何在 BSC 中处理？

编程问答 2022-05-03

问题描述

嗨，我正在使用 web3 和 react 做 BSC DApp。我对这个领域很陌生。

我在调用 approve 后发现，transfer（或在我的例子中是 zapInToken）不会因为抱怨没有足够的津贴而成功。所以我添加了 wait allowance 以存在 10 秒，但似乎在 10 秒后很多次（50% 的机会）仍然不存在配额。请检查以下代码以获取更多信息。

理论上，approve 会生成一个交易，并且出现的时间取决于。如果是这样，approve、wait for allowance 和 transfer 是否是标准模式？

谢谢！

const bepContract = getContract(getAddress(from),erc20ABI,library,account)
const tx = await bepContract.approve(getAddress(contracts.zap),weiAmount)
if (!tx) {
    throw new Error('Failed to approve transaction')
}
await waitAllowance(bepContract,account,getAddress(contracts.zap),weiAmount,10) // <-- and it will stuck here in most time,the code waits for the allowance is present
await getZapContract().zapInToken(getAddress(from),getAddress(to)).then(logInfo).catch(logError)

waitAllowance 如下所示

const waitAllowance = async (
  contract: Contract,account: string,to: string,allowanceNeeded: string,timesLeft: number
): Promise<void> => {
  if (timesLeft > 1) {
    const currentAllowance = await contract.allowance(account,to)
    // console.log(`I want ${allowanceNeeded},and current is ${currentAllowance} `)
    const needed = new BigNumber(allowanceNeeded)
    const current = new BigNumber(currentAllowance.toString())
    if (current.isGreaterThanorEqualTo(needed)) {
      return
    }
    await new Promise((res) => setTimeout(res,1000))
    await waitAllowance(contract,to,allowanceNeeded,timesLeft - 1)
  }
  throw new Error('wait allowance Failed for many times.')
}

解决方法

我想通了，我需要tx.wait，所以工作代码如下：

const bepContract = getContract(getAddress(from),erc20ABI,library,account)
const tx = await bepContract.approve(getAddress(contracts.zap),weiAmount)
if (!tx) {
    throw new Error('Failed to approve transaction')
}
const tx = await waitAllowance(bepContract,account,getAddress(contracts.zap),weiAmount,10)
const txResult = await tx.wait()
if (txResult.status !== 1) {
    throw new Error('Failed approve')
}
const txZap = await getZapContract().zapInToken(getAddress(from),getAddress(to))
const txZapResult = await txZap.wait()
if (txZapResult.status !== 1) {
    throw new Error('Failed zap')
}

查看此doc的更多详情

erc20ethereumweb3js