Add gas limit multiplier parameter on usePrepareContractWrite

[volkyeth]

Allow passing a gas limit multiplier on usePrepareContractWrite, to support use cases where there's considerable gas usage variability.

Why?

One example: on auction contracts with extension for last-minute bids: if the bid is placed when the extension is triggered, the gas usage is considerably higher. If usePrepareContractWrite estimated the gas before that threshold, the gas limit might be too low and lead to a failed tx.

The existing alternatives lead to bad dev experience:

• using a static gas limit (not very straightforward or future-proof)
• calculating gas limit manually (there's no hook for that on wagmi)
• using a lower staleTime can increase the node usage considerably

Suggested API:

gasLimitMultiplier prop on usePrepareContractWrite config

example:

const { config, error } = usePrepareContractWrite({
    address: '0xecb504d39723b0be0e3a9aa33d646642d1051ee1',
    abi: wagmigotchiABI,
    functionName: 'feed',
    gasLimitMultiplier: 1.2,
  })

The importance of this issue

There's a bunch of discussions suggesting the need for something like this:

• useContract gas limit #839
• How to estimate gas using Wagmi's contactwrite and rewrite contractwrite to send transactions based on the gas estimate multiplied by 1.5. #1943
• Gas Limit #1750
• How to get the minimum gasLimit? #1921

[volkyeth]

My current workaround is multiplying manually, btw:

const { config } = usePrepareContractWrite({
    address: '0xecb504d39723b0be0e3a9aa33d646642d1051ee1',
    abi: wagmigotchiABI,
    functionName: 'feed',
  })
  
  const { data, isLoading, isSuccess, write } = useContractWrite({
    ...config,
    request: {
      ...config.request,
      gasLimit: config.request.gasLimit.mul(115).div(100), // equivalent to a gasLimitMultiplier of 1.15
    },
  })

[pppest]

this works for you? have a similar case and tired recklesslySetUnpreparedOverrides.

[AndonMitev]

@volkyeth how you get gasLimit from config returned by usePrepareContractWrite

const calldata = {
    abi: ReferralAbi,
    address: ReferralAddress,
    functionName: 'generateCodes',
  };

  const {
    config,
    isLoading: isLoadingSimulatedTx,
    error: errorSimulatedTx,
  } = usePrepareContractWrite(calldata);

  console.log(config);

gas && gasPrice are undefined

[0x33dm]

@volkyeth did you find an elegant solution in the end?

@AndonMitev usePrepareContractWrite is not available anymore on wagmi 2.x I wonder if you found another way of doing it using wagmi?

[tmm]

https://wagmi.sh/react/guides/migrate-from-v1-to-v2#removed-prepare-hooks

[0x33dm]

@tmm thanks for the quick reply.

I looked into those options and turns out useSimulateContract won't return the gas / gasLimit which is the value we're trying to fetch in order to add the extra "gas" buffer.

Later on I realised I had to use viem encodeFunctionData to encode the writeParams and then use that to call useEstimateGas from wagmi.

My solution in the end looks like this:

useEstimateExtraGas

/**
 * Estimates gas for a transaction then adds extra amount, for instance
 * using BigInt(120) as percentage will add 20% extra gas to the estimated
 * amount
 */

import { encodeFunctionData, type WriteContractParameters } from 'viem'
import { useEstimateGas } from 'wagmi'

export function useEstimateExtraGas(
  params: WriteContractParameters,
  percentage: bigint
) {
  const data = params ? encodeFunctionData(params) : null

  const { data: estimatedGas } = useEstimateGas(
    data ? { data, to: params.address } : undefined
  )

  const estimatedWithExtra = estimatedGas
    ? (estimatedGas * percentage) / BigInt(100)
    : null

  return estimatedWithExtra
}