How to get a returned value from a function call using useContractWrite?

[pablohpsilva]

On my contract level I have a function like:

function myFunc() external view returns(string) {
    // change my contract state somewhere
   // the returning value is a string, like an id
    return "uuid1234";
}

In my application, I have a useContractWrite that will call that function, like:

const useMyFunction = () => {
  const contractWrite = useContractWrite({
    address: "MY_CONTRACT_ADDRESS",
    abi: ContractAbi,
    functionName: "myFunc"
  });
  const waitForTransaction = useWaitForTransaction({
    hash: contractWrite?.data?.hash,
  });

  return {
    ...contractWrite,
    ...waitForTransaction,
    data: {...(contractWrite?.data ?? {}), ...(waitForTransaction?.data ?? {})},
    isLoading: contractWrite?.isLoading || waitForTransaction?.isLoading,
    write: contractWrite.write
  }
}

Calling this hook will return a bunch of data, except the string "uuid1234" which should come as a return value from the function called in my contract.

Here's an example output from the useMyFunction hook when write is called:

{
    "data": {
        "hash": "...",
        "to": "...",
        "from": "...",
        "contractAddress": null,
        "transactionIndex": 0,
        "gasUsed": {
            "type": "BigNumber",
            "hex": "0x061455"
        },
        "logsBloom": "...",
        "blockHash": "...",
        "transactionHash": "...",
        "logs": [],
        "blockNumber": 16804122,
        "confirmations": 1,
        "cumulativeGasUsed": {
            "type": "BigNumber",
            "hex": "0x061455"
        },
        "effectiveGasPrice": {
            "type": "BigNumber",
            "hex": "0x062b85e900"
        },
        "status": 1,
        "type": 2,
        "byzantium": true
    },
    "error": null,
    "isError": false,
    "isIdle": false,
    "isLoading": false,
    "isSuccess": true,
    "status": "success",
    "variables": {...},
    "fetchStatus": "idle",
    "isFetched": true,
    "isFetchedAfterMount": true,
    "isFetching": false,
    "isRefetching": false,
    "internal": {...}
}

How can I get this value from the contract ?

[jxom]

Unfortunately, you can't retrieve the return value from a contract write directly in wagmi right now. You may want to do this directly via the ethers callStatic contract function:

const contract = useContract({ address, abi })
const result = contract.callStatic.myFunc()

[zkSoju]

Is there any intentions on making this possible?

[jxom]

Yep, usePrepareContractWrite also returns the result in v1.

[gkfyr]

It still doesn't supported? @jxom

[jxom]

Use useSimulateContract