javascript - 从此Promise返回数据时，为什么会变得不确定？

以下data未定义返回：

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...
}

当我记录时，您可以在promise = searchedTickers.that;上方看到，我看到了要返回的数据。但是，它永远不会恢复到我原来的selectSearchedTicker函数。



更新：添加了此代码，该代码位于所有内容之前，我必须制作一个Promise链，因为我需要等到调用TickersSelectFactory.selectSearchedTicker并完成这些操作的结果之后，再调用2个$emit。

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);

最佳答案

解决问题的正确方法是使用.then()提供的内置链接，并消除多余的$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;
        });
    ...
}

在您的第一个功能中类似：

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;
    });
}

（请注意，在函数开始处添加了新的return，以确保此函数的调用者正确接收到Promise）

关于javascript - 从此Promise返回数据时，为什么会变得不确定？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/34818488/