英文:
Wagmi useContractEvent listener can't access useState variable
问题
I'm stuck on this problem that I really can't make sense of.
当尝试从useContractEvent中的listener函数中访问hash状态变量时，它是未定义的。
我可以在useContractEvent之外的地方访问hash状态变量，但是一旦事件被触发并且我尝试在listener函数内部读取hash状态变量，它就变成了未定义的。
这是上下文问题吗？
英文:
I'm stuck on this problem that I really can't make sense of.
When trying to access the hash state variable from the listener function in useContractEvent it is undefined.
I can access the hash state variable outside of the listener function in useContractEvent but as soon as the event is triggered and I try to read the hash state variable inside the listener function it is undefined.
Is it a context issue?
const [hash, setHash] = useState<`0x${string}` | undefined>();useContractEvent({address: contract.address as `0x${string}`,abi: contract.abi,eventName: "SomeEvent",listener(log) {console.log(hash) // undefinedif (log[0]?.transactionHash != hash) return;// never reached},});const { write } = useContractWrite({address: contract.address as `0x${string}`,abi: contract.abi,functionName: "someFunction",args: [],onSuccess(data) {setHash(data.hash);},});return (<button onClick={() => write?.()}>Go</button>);
答案1
得分: 1
Yes, the issue you're facing is likely due to a context problem related to closures and the asynchronous nature of useContractEvent and useContractWrite.
一种方法是使用 ref 来始终访问 hash 的最新值。
const hashRef = useRef<`0x${string}` | undefined>();useContractEvent({address: contract.address as `0x${string}`,abi: contract.abi,eventName: "SomeEvent",listener: (log) => {console.log(hashRef.current); // 这将始终记录 `hash` 的最新值if (log[0]?.transactionHash !== hashRef.current) return;// 不会执行到这里},});const { write } = useContractWrite({address: contract.address as `0x${string}`,abi: contract.abi,functionName: "someFunction",args: [],onSuccess(data) {hashRef.current = data.hash;},});return <button onClick={() => write?.()}>Go</button>;
英文:
Yes, the issue you're facing is likely due to a context problem related to closures and the asynchronous nature of useContractEvent and useContractWrite.
One approach is to use ref to always access the latest value of hash
const hashRef = useRef<`0x${string}` | undefined>();useContractEvent({address: contract.address as `0x${string}`,abi: contract.abi,eventName: "SomeEvent",listener: (log) => {console.log(hashRef.current); // This will always log the latest value of `hash`if (log[0]?.transactionHash !== hashRef.current) return;// never reached},});const { write } = useContractWrite({address: contract.address as `0x${string}`,abi: contract.abi,functionName: "someFunction",args: [],onSuccess(data) {hashRef.current = data.hash;},});return <button onClick={() => write?.()}>Go</button>;
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