在解析来自第一个请求的数据后触发第二个 httpRequest

Question

我目前有一个函数可以生成 httpRequest 并将收到的 json 解析为 array 的 url。我想在第一个请求完成并且数据被解析后触发第二个 httpRequest，在我尝试过的两种解决方案下 return null。

解决方案1

var promises1 = [];
Parse.Cloud.define("FetchData", function(request, response) {
    var promises = _.map(urls, function(url) {
        return Parse.Cloud.httpRequest({ url:url });
        });
    Parse.Promise.when(promises).then(function() {
        createSearchUrls(arguments)
        //Creates an array of urls from request data to be used in second http request
         });       
    //Fire second HTTP request here after urls have been created from first request data
    var promises1 = _.map(appTitles, function(appTitles) {
        return Parse.Cloud.httpRequest({ url: appTitles});
        });
    Parse.Promise.when(promises1).then(function() {
        //nothing returned
        response.success(_.toArray(arguments));
        }, function (error) {
            response.error("Error: " + error.code + " " + error.message);
        });
    });

解决方案 2（在 createSearchUrl() 函数后使用 then

    Parse.Cloud.define("FetchData1", function(request, response) {
        var promises = _.map(urls, function(url) {
            return Parse.Cloud.httpRequest({ url:url });
            });
        Parse.Promise.when(promises).then(function() {
  //Creates an array of urls from request data to be used in second http request
            createSearchUrls(arguments).then( function() {
                //Fire second HTTP request here after urls have been created from first request data
                promises_1 = _.map(appTitles, function(appTitles) {
                    return Parse.Cloud.httpRequest({ url: appTitles});
                    });
                })
            });
       Parse.Promise.when(promises_1).then(function() {
            //nothing returned
            response.success(_.toArray(arguments));
            }, function (error) {
                response.error("Error: " + error.code + " " + error.message);
            });
        });

createSearchUrls()

function createSearchUrls(arguments){
    for (a = 0; a < arguments.length; a++){
        var json = JSON.parse(arguments[a].text);
        for (i = 0; i < json.feed.entry.length; i++) {
            var urlEncoded = encodeURI(ENCODE JSON DATA);
            var finalUrl = 'URL HERE';

            appTitles.push(finalUrl);
        }
    }
    return appTitles;
}

Answer 1

看起来制作一系列 httpRequest 并收集结果的想法是可以而且应该被分解的....

function manyRequests(urls) {
    var promises = _.map(urls, function(url) {
        return Parse.Cloud.httpRequest({ url:url });
    });
    return Parse.Promise.when(promises).then(function() {
        return _.toArray(arguments);
    });
}

现在只需调用两次即可....

Parse.Cloud.define("FetchData1", function(request, response) {
    manyRequests(urls).then(function(results) {
        createSearchUrls(results);  // assigns to the gobal "appTitles"
        return manyRequests(appTitles);
    }).then(function(result) {
        response.success(result);
    }, function(error) {
        response.error(error);
    });
});

也就是说，调用（大概是全局定义的）url 列表并收集结果。从这些结果中，运行一个本地函数生成另一个 url 列表（可能是将它们分配给全局的），调用这些函数并将结果 return 发送给客户端。

在解析来自第一个请求的数据后触发第二个 httpRequest

Fire second httpRequest after parsing data from first request

javascript

parse-platform

parse-cloud-code