承諾不解決，然后再返回

Question

我很難弄清楚諾言如何運作。 我有以下代碼，正在通過數組執行迭代。

 runOpts.automationResults.reduce(function (p, val) { return p.then(function () { return pd.run(val); }); }, Promise.resolve()).then(function (rallyResults) { console.log('returned from method'); console.log('rallyResults ', rallyResults); }, function (err) { console.log('error in reduce', err); }); 

它正在調用以下方法

 ProcessDatabase.prototype.run = function (options) { return new Promise((resolve, reject) => { var dal = new db(); var resultsArray = { results: [], options: [], testSet: [], testIteration: '', multipleSets: 0, totalCount: 0 } resultsArray.options = options; dal.getAutomationResultsByBuild(options.Build).then((results) => { resultsArray.results = results; resultsArray.totalCount = results.data.length; resolve(resultsArray); }) }).then(function (resultsArray) { var results = []; //console.log('resultsArray', resultsArray); //console.log(`Starting Rally publishing for Build '${resultsArray.options.Build}'...`) if (resultsArray.options.Executiontype == 'ci') { rallyApi.autoDiscoverTestSets().then((sets) => { resultsArray.testSet = sets.sets; resultsArray.testIteration = sets.iteration; resultsArray.multipleSets = sets.sets.length > 1; results.push(resultsArray); console.log('results', results); }, (err) => { reject(err); }); // totalResults = totalResults + results.data.length; } else { rallyApi.addTestSet('Automation: ' + resultsArray.options.type + ' - ' + resultsArray.options.build, config.get('rally.projects.testing.ref'), null, resultsArray.options.SessionUser).then((resp) => { //console.log(resp); console.log('New test set ' + resp.FormattedID + ' created.'); resultsArray.multipleSets = 0; resultsArray.testSet = resp.FormattedID; //console.log('resultsArray', resultsArray); results.push(resultsArray); console.log('results', results); }, (err) => { console.log(err); }); } console.log('results', results); return Promise.all(results); }) } 

我已經嘗試了幾種不同的迭代方式，並且總是在ProcessDatabase.prototype.run方法中完成結果之前返回到調用.reduce。

我已經輸入了控制台日志，這就是我得到的。 我可以看到最終結果數組具有我需要的所有信息。 我只是無法弄清楚如何將其傳遞回調用.reduce。

 ---These are actually from the .reduce and are written to the log before the results in the method called returned from method rallyResults [] **----These are from the ProcessDatabase.prototype.run method called** **This is the contents of the "results" set the first iteration through** -- Found 2 test sets. results [ { results: { _success: true, _message: '', _data: [Array] }, options: { Executiontype: 'ci', Build: 'test_030518_103956', Environment: 'dev', SessionUser: 'https://rally1.rallydev.com/slm/webservice/v2.0/user/165547093296' }, testSet: [ [Object], [Object] ], testIteration: 'https://rally1.rallydev.com/slm/webservice/v2.0/iteration/184203152680', multipleSets: true, totalCount: 4 } ] New test set TS2969 created. **This is the contents of the "result" set after the second iteration through and what I trying to get passed back to the calling .reduce.** results [ { results: { _success: true, _message: '', _data: [Array] }, options: { Executiontype: 'ci', Build: 'test_030518_103956', Environment: 'dev', SessionUser: 'https://rally1.rallydev.com/slm/webservice/v2.0/user/165547093296' }, testSet: [ [Object], [Object] ], testIteration: 'https://rally1.rallydev.com/slm/webservice/v2.0/iteration/184203152680', multipleSets: true, totalCount: 4 }, { results: { _success: true, _message: '', _data: [Array] }, options: { Executiontype: 'regression', Build: 'test_030518_110447', Environment: 'dev', SessionUser: 'https://rally1.rallydev.com/slm/webservice/v2.0/user/165547093296' }, testSet: 'TS2969', testIteration: '', multipleSets: 0, totalCount: 6 } ] 

任何幫助將不勝感激。 謝謝克里斯汀

Answer 1

這段代碼中有很多問題，但是主要的問題是，當您在.then()處理程序中運行另一個異步操作時，您必須從.then()返回該諾言才能正確地將其鏈接到主程序中。承諾鏈。 如果您不這樣做，那么父承諾根本就不會鏈接到該內部承諾（它變成了自己的獨立承諾鏈，您無法對其進行監視），並且父承諾不會等待內部承諾。

以下是所做的更改：

1. 刪除不必要地將承諾包裝在另一個承諾中的承諾反模式（只需返回您已經擁有的承諾）
2. 從.then（）處理程序中返回嵌套的Promise以適當地鏈接它們
3. 將錯誤日志整合到一處並重新拋出錯誤，以便正確返回
4. 刪除Promise.all() 。
5. 刪除results.push(resultsArray); 因為似乎沒有任何意義。 我在下面編寫代碼的方式是，最高級別的承諾將解析為resultsArray並且由於其中只有一個，因此我認為無需將其嵌入另一個數組中。

這是修改后的代碼：

ProcessDatabase.prototype.run = function (options) {
    var dal = new db();
    var resultsArray = {
        results: [],
        options: {},
        testSet: [],
        testIteration: '',
        multipleSets: 0,
        totalCount: 0
    }
    resultsArray.options = options;
    return dal.getAutomationResultsByBuild(options.Build).then((results) => {
        resultsArray.results = results;
        resultsArray.totalCount = results.data.length;
        return resultsArray;
    }).then(function (resultsArray) {
        //console.log('resultsArray', resultsArray);
        //console.log(`Starting Rally publishing for Build '${resultsArray.options.Build}'...`)

        if (resultsArray.options.Executiontype == 'ci') {

            return rallyApi.autoDiscoverTestSets().then((sets) => {
                resultsArray.testSet = sets.sets;
                resultsArray.testIteration = sets.iteration;
                resultsArray.multipleSets = sets.sets.length > 1;
                return resultsArray;
            });
        } else {
            return rallyApi.addTestSet('Automation: ' + resultsArray.options.type + ' - ' + resultsArray.options.build, config.get('rally.projects.testing.ref'), null, resultsArray.options.SessionUser).then((resp) => {
                //console.log(resp);
                console.log('New test set ' + resp.FormattedID + ' created.');
                resultsArray.multipleSets = 0;
                resultsArray.testSet = resp.FormattedID;
                return resultsArray;
            });
        }

    }).catch(err => {
        // log error and rethrow
        console.log(err);
        throw err;
    });
}