Question

我遇到了一些问题，从嵌套的Promises和回调中返回数据，从我的组件中我首先调用Api方法找到checkid，当我收到checkid时，我将检查该id的状态。另一件事，当我检查状态时，我正在使用第三方服务，因此数据不会立即返回。所以我称状态api最多10次（时间超过3秒），直到我收到我的数据。这是我的第一个实现。

deviceService使用请求库

构成简单的API方法

    For Ex: 

      const deviceService ={
        fetchID(param1){
            request.get('https://.....')
        }
      }

//在反应组件文件中。我将API称为

       API.getDeviceLockStatus(param1).then(data => {
           //I need data after i reciving the value from 3rd party server
          if (data) {
             //DO SOMETHING
           }
       });

API.js文件：

            var API = {
                getDeviceLockStatus(param1) {        
                    return deviceService.fetchID(param1).then(checkID => {

                        console.log('Got checkID here')
                        if (checkID) {
                            callStatus(checkID);
                        }
                    }, handleError);
                }
            }

            function callStatus(checkID) {
                return deviceService.fetchStatus(checkID).then(status => {
                    // If i receive the response from 3rd party Server i will have status.body.isAvailable = true (or False)
                    // if Not i will recieve status with status.checkID (this checkID is what i have supplied)
                    if (status.body.isAvailable) {
                        return status
                    } else {
                        setTimeout(callBackFunction(status.checkID), 3000)
                    }
                },han)
            }
            callBackFunction(checkID) {
                callStatus(checkID);
            }
            function handleError(){
                // Error will be Handled
            }

所以问题是当我调用API.getDeviceLockStatus（param1）时..它会立即返回undefined。

有人可以帮助我更好地做到这一点，或者在获取真实数据后返回实际值。

提前致谢。

Answer 1

查看API.js，没有太多要改变

var API = {
    getDeviceLockStatus(param1) {
        return deviceService.fetchID(param1).then(checkID => {
            console.log('Got checkID here')
            if (checkID) {
                return callStatus(checkID); // added return
            }
        }, handleError);
    }
}

function callStatus(checkID) {
    return deviceService.fetchStatus(checkID).then(status => {
        // If i receive the response from 3rd party Server i will have status.body.isAvailable = true (or False)
        // if Not i will recieve status with status.checkID (this checkID is what i have supplied)
        if (status.body.isAvailable) {
            return status
        } else { // here one way to do a simple delay/retry with a Promise
            return new Promise(function(resolve) {
                setTimeout(resolve, 3000);
            }).then(function() {
                return callStatus(status.checkID);
            });
        }
    }, handleError)
}

function handleError() {
    // Error will be Handled
}

如何从嵌套的promises中获取返回值

1 个答案: