Question

我有一个自定义函数，可正确返回用户详细信息的缓存对象。此外，该函数会事先检查缓存是否为空，并在必要时进行API调用以检索适当的数据。但是，当我从角度ui-router解析时调用此函数时，它仍然会变得未定义。我不明白...因为自定义函数中的所有控制台打印语句都显示正在返回正确的对象。

function getCache(UserService) {
    if(cacheIsEmpty) {
        UserService.getProfile().then(function (profile) {
            // check to see profile returned correctly
            console.dir(profile);

            // set cache using returned profile
            ...

            // create object loaded from cache
            var cacheObj = {
                firstName: // get from cache
                lastName:  // get from cache
                ...
            }

            // check if my object is correctly created
            console.log(cacheObj):

            // now return this correctly created object
            return cacheObj;

        });

    } else {

        // the following creates object directly from cache
        // since it is NOT empty and can be used
        var cacheObj = {
            firstName: // get from cache
            lastName:  // get from cache
            ...
        }

        // print to check object is correct
        console.dir(cacheObj);

        // now return it
        return cacheObj;
    }

}

在解决方案中，对该函数的调用将按照定义返回...尽管该对象正确地从对象返回。

...
resolve: {
    cacheObj: function(UserService) {

        // call the getCache function
        var returnedUserObject = getCache(UserService);

        // printing the object here shows that it is undefined
        console.log(returnedUserObject);

        // return the object to the controller
        return returnedUserObject;
    }
}

Answer 1

您应该从var id =[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20];函数返回一个承诺，以便getCache认识到，直到承诺得到解决，我需要等待。在这里，您尚未通过resolve方法返回承诺，您正在进行if(cacheIsEmpty)方法调用。虽然从UserService.getProfile函数的承诺中返回数据并不意味着您将返回承诺。

<强>代码

.then

<强>解析

function getCache(UserService) {
    //return promise from both the places, if & else
    if(cacheIsEmpty) {
        //return promise here
        return UserService.getProfile().then(function (profile) {
            // check to see profile returned correctly
            console.dir(profile);

            // set cache using returned profile
            ...

            // create object loaded from cache
            var cacheObj = {
               firstName: // get from cache
               lastName:  // get from cache
               ...
            }
            //return cacheObj from here when promise resolved
            return cacheObj;
        });
    } else {
        //create cached cacheObj from cache and return it
        return $q.resolve(cacheObj)
    }
}

Angular ui-router resolve是调用正确返回对象的函数，但最终仍然未定义。为什么呢？

1 个答案: