React本机挂钩状态不会在函数内更新

如何解决React本机挂钩状态不会在函数内更新

如果我的 list.lenght> 10，我的任务是导航到另一个屏幕。 我的列表已使用hooks redux正确更新。

我有ActionSheetIOS.showActionSheetWithOptions，当我按“ go”时，我想检查一个list.lenght并检查它是否大于10。

状态（list.lenght）正确更新，但在我的函数中未更新。在我的职能中，状态是第一个状态。

我试图将函数放入useEffect中，我认为在更新列表时该值会更新，但是不会。

这是我的代码

export default function CustomersList(props) {

    const userId = useSelector(state => state.loggedReducer.userId);
    const customers = useSelector(state => state.customers.customers);

    const dispatch = useDispatch();

    const [refreshing,setRefreshing] = React.useState(false);
    const onRefresh = React.useCallback(() => {
        dispatch(fetchCustomers(userId));
    },[]);

    /**
     * Add Right icon on header
     * */
    React.useLayoutEffect(() => {
        props.navigation.setOptions({
            headerRight: () => (<Ionicons name="ios-more" size={24} color="white" onPress={() => {onPress()}} style={{marginRight: 20}}/>),});
    },[props.navigation]);

    let clickGo;

    const onPress = () => {
        console.log("rendered");
        ActionSheetIOS.showActionSheetWithOptions(
            {
                options: ["Cancel","go"],cancelButtonIndex: 0,},buttonIndex => {
                switch (buttonIndex) {
                    case 0: // cancel Action
                        break;
                    case 1: // Go
                        clickGo();
                        break;
                }
            }
        );
    }

    useLayoutEffect(() => {
        console.log(customers.length); // updated state

        clickGo = () => {
            console.log("state",customers.length); // old state :(
            if(customers.length < 10){
                props.navigation.navigate("NewCustomer");
            }else{
                alert("upgrade to premium")
            }
        }
    },[customers])

}

解决方法

设置clickGo的逻辑有些偏离-最简单的解决方法是删除此逻辑并将其全部放入onPress

const onPress = () => {
    console.log("rendered");
    ActionSheetIOS.showActionSheetWithOptions(
        {
            options: ["Cancel","go"],cancelButtonIndex: 0,},buttonIndex => {
            switch (buttonIndex) {
                case 0: // cancel Action
                    break;
                case 1: // Go
                    if (customers.length < 10) {
                        props.navigation.navigate("NewCustomer");
                    } else {
                        alert("upgrade to premium")
                    }
                    break;
            }
        }
    );
}

还要-确保将依赖项添加到onRefresh中的数组中！

,

我找到了解决方案，已将所有脚本放入这样的useEffect中。

useEffect(() => {

    console.log(customers.length);

    props.navigation.setOptions({
        headerRight: () => (<Ionicons name="ios-more" size={24} color="white" onPress={() => {onPress()}} style={{marginRight: 20}}/>),});

    const onPress = () => {
        ActionSheetIOS.showActionSheetWithOptions(
            {
                options: ["Cancel",strings.createNewCustomer,strings.connectWithCustomer],buttonIndex => {
                switch (buttonIndex) {
                    case 0: // cancel Action
                        break;
                    case 1: // Create new Client Action
                        if(!premium){
                            if(customers.length < 10){
                                props.navigation.navigate("NewCustomer");
                            }else {
                                Alert.alert(strings.upgradeToPremium)
                            }
                        }else {
                            props.navigation.navigate("NewCustomer");
                        }
                        break;
                    case 2: // Connect
                        if(!premium){
                            if(customers.length < 10){
                                openConnectModal();
                            }else {
                                Alert.alert(strings.upgradeToPremium)
                            }
                        }else {
                            openConnectModal();
                        }
                        break;
                }
            }
        );
    }


},[customers])