angularjs $q.all 用于嵌套承诺

Question

尝试在 AngularJS (1.6) 中获取嵌套的异步 REST 请求，然后在所有请求完成后执行代码。

我尝试使用 $q.all，但似乎这不会考虑内部请求（剧集请求）。

如何修改以下示例，以便在所有请求完成后执行代码？

// foreach series --> load series details & seasons, foreach season --> load episodes
// when all requests are completed: do something

var requests = []

// e.g. series = [1]
series.forEach(function(seriesId) {
    requests.push(loadSeriesDetails(seriesId).then(function(data) {
        console.log("received details for series "+seriesId)
        // e.g. {id:1, title:"show 1"}
    }))
    requests.push(loadSeasons(seriesId).then(function (data) {
        console.log("received seasons for series "+seriesId+": ", data.seasons.length)
        // e.g. [{id:11, title:"season 1"}, {id:12, title:"season 2"}]
        data.seasons.map(function(e) {return e.id}).forEach(function(seasonId) {
            requests.push(loadEpisodes(seasonId).then(function (data) {
                console.log("received episodes for season "+seasonId+": ", data.episodes.length)
                // e.g.
                // season 11: [{id:111, title:"episode 1-1-1"}, {id:112, title:"episode 1-1-2"}, {id:113, title:"episode 1-1-3"}]
                // season 12: [{id:121, title:"episode 1-2-1"}, {id:122, title:"episode 1-2-2"}]
            }))
        })
    }))
})

$q.all(requests).then(function(result) {
    console.log("*** all requests completed ***")
    console.log(result.length)
})

上面的例子会 return 2 (1x loadSeriesDetails, 1x loadSeasons) 而不是 4 (1x loadSeriesDetails, 1x loadSeasons, 2x loadEpisodes).

建议？提前致谢！

更新： 每个请求函数如下：

loadSeriesDetails = function(id) {
  url = "..."+id

  return $http.get(url).then(
    function (result) {
      return result.data
    }, function (error) {
      ̶r̶e̶t̶u̶r̶n̶ ̶e̶r̶r̶o̶r̶ 
      throw error;
  });
}

Answer 1

您的 requests 数组应该包含您将其传递给 $q.all 时需要解决的所有承诺。目前，您正在将 loadEpisodes 的承诺添加到 requests 之前的承诺解决后。

您可以将其拆分，以便内部部分 return 属于自己的 $.q.all，这将成为链接：

    var requests = [];

    series.forEach(function (seriesId) {
        requests.push(loadSeriesDetails(seriesId).then(function (data) {
            console.log("received details for series " + seriesId);
            return data;
        }));

        requests.push(loadSeasons(seriesId).then(function (data) {
            console.log("received seasons for series " + seriesId + ": ", data.seasons.length);
            return loadAllEpisodes(data.seasons);
        }));
    });

    function loadAllEpisodes(seasons) {
        var requests = seasons.map(function (season) {
            return loadEpisodes(season.id).then(function (data) {
                console.log("received episodes for season " + season.id + ": ", data.episodes.length);
                return data;
            });
        });

        return $q.all(requests);
    }

    q.all(requests).then(function(result) {
        console.log("*** all requests completed ***");
        console.log(result.length);
    });

请注意，在您的示例中，您仍然只会在从外部 $q.all 编辑 return 的最终数组中看到 2 个结果，因为您正在从最后一个承诺中获得结果每条链。因此，您可能需要调整 return 语句，以便它们按照您需要的方式对信息进行分组。

Answer 2

的变体，更接近原始代码片段。

// foreach series --> load series details & seasons, foreach season --> load episodes
// when all requests are completed: do something

var requests = []

// e.g. series = [1]
series.forEach(function(seriesId) {
    requests.push(loadSeriesDetails(seriesId).then(function(data) {
        console.log("received details for series "+seriesId)
        // e.g. {id:1, title:"show 1"}
    }))
    requests.push(loadSeasons(seriesId).then(function (data) {
        console.log("received seasons for series "+seriesId+": ", data.seasons.length)
        // e.g. [{id:11, title:"season 1"}, {id:12, title:"season 2"}]
        var innerRequests = [] // <<<==============
        data.seasons.map(function(e) {return e.id}).forEach(function(seasonId) {
            innerRequests.push(loadEpisodes(seasonId).then(function (data) {
                console.log("received episodes for season "+seasonId+": ", data.episodes.length)
                // e.g.
                // season 11: [{id:111, title:"episode 1-1-1"}, {id:112, title:"episode 1-1-2"}, {id:113, title:"episode 1-1-3"}]
                // season 12: [{id:121, title:"episode 1-2-1"}, {id:122, title:"episode 1-2-2"}]
            }))
        })
        return $q.all(innerRequests) //  <<<==============
    }))
})

$q.all(requests).then(function(result) {
    console.log("*** all requests completed ***")
    console.log(result.length)
})

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