为什么从这个 Promise 返回数据时我会得到 undefined？

Question

data 返回未定义：

function selectSearchedTicker(ticker, load) {
    var deferred = $q.defer();

    GetTickersFactory.getTickers('searched', load).then(function(data) {
        console.log('data',data);
        var tempTickers = GetTickersFactory.returnSearchedTickers();
        $rootScope.$emit("select.searched.ticker", tempTickers);
        deferred.resolve();
    });

    return deferred.promise;
}

这是GetTickersFactory.getTickers函数：

function getTickers(type, load, searchedTicker, cached) {
    type = type || 'portfolio';
    load = load || '';
    searchedTicker = searchedTicker || {};

    var deferred = $q.defer(),
        promise;

    if (cached) portfolioCached = cached;

    //other code remains same
    tickersPane = ScopeFactory.getScope('tickersPanel');

    switch (type) {
        case 'searched':
            return ApiFactory.getTickers(null, load).then(function(data) {

                //renderTickers just does logic, no more API call
                searchedTickers.that = renderTickers(data.data.tickers, searchedTicker, 'searched');
                promise = searchedTickers.that;
                console.log('promise',promise); // <-- there is data here
                deferred.resolve(promise);
                // return returnData(searchedTickers.that);
            });
            break; // <-- after hitting this break, chrome tools hits the Angular code
        //...
    }

    return deferred.promise; // <- also tried return promise

    // other functions...
}

你可以在上面看到 promise = searchedTickers.that; 当我记录它时，我在里面看到了我想要返回的数据。但是它永远不会回到我原来的 selectSearchedTicker 函数。

Update：在所有内容之前添加了这段代码，我必须制作一个承诺链，因为我需要等到 TickersSelectFactory.selectSearchedTicker 被调用以及那些结果动作完成后，我调用 2 $emit's.

TickersSelectFactory.selectSearchedTicker(fullTicker.ticker, selectTickerUrl).then(function(res) {
    console.log('selectSearchedTicker promise returned');
    $rootScope.$emit("clear.tags.array");
    $rootScope.$emit("search.ticker.clicked", fullTicker);
});

最初看起来像这样，给我带来了问题：

TickersSelectFactory.selectSearchedTicker(fullTicker.ticker, selectTickerUrl);
$rootScope.$emit("clear.tags.array");
$rootScope.$emit("search.ticker.clicked", fullTicker);

Answer 1

弄清楚了，我正在返回我的 ApiFactory 调用，这结束了我的承诺链，然后我才能将数据添加到承诺中以向上解决。

// return ApiFactory.getTickers(null, load).then(function(data) {
ApiFactory.getTickers(null, load).then(function(data) {

case 'searched':
    // With the return below, the code never got in to set the promise up and resolve it
    // return ApiFactory.getTickers(null, load).then(function(data) {
    ApiFactory.getTickers(null, load).then(function(data) {
        searchedTickers.that = renderTickers(data.data.tickers, searchedTicker, 'searched');
        promise = searchedTickers.that;
        console.log('searched promise',promise);
        deferred.resolve(promise);
    });
    break;

Answer 2

您问题的正确解决方案是使用 .then() 提供的 built-in 链接，并消除无关的 $q.defer() 对象：

switch (type) {
    case 'searched':
        return ApiFactory.getTickers(null, load).then(function(data) {
            searchedTickers.that = renderTickers(data.data.tickers, searchedTicker, 'searched');
            return searchedTickers.that;
        });
    ...
}

与您的第一个函数类似：

function selectSearchedTicker(ticker, load) {
    return GetTickersFactory.getTickers('searched', load).then(function(data) {
        console.log('data',data);
        var tempTickers = GetTickersFactory.returnSearchedTickers();
        $rootScope.$emit("select.searched.ticker", tempTickers);
        return tempTickers;
    });
}

（注意函数开头的新 return，确保此函数的 caller 正确接收 Promise）

为什么从这个 Promise 返回数据时我会得到 undefined？

Why am I getting undefined when returning data from this Promise?

javascript

angularjs

angular-promise