角度回調或承諾陷阱返回價格

Question

我正在試圖讓這個工作正常。我已經嘗試過回調和承諾，並且對兩者均開放。我使用Joe Eames在Pluralsight類中制定的Mean Stack來模擬我的代碼。我仍然在學習，所以如果不正確，請原諒我的術語，但這裏是如何與代碼一起工作的，如下圖所示。

我的界面調用flQuestionCrudCtrl.createQuestion，調用flQuestionCrud.createNewQuestion調用flQuestion.Create。 flQuestion.Create向寫入mongodb集合的服務器發出http post請求。似乎一切正常，數據寫入數據庫，我可以看到每個控制檯日誌flQuestionCrud中的返回值。當我嘗試讀取flQuestionCrudCtrl中的「data」返回參數時，「錯誤：數據未定義」。我已經嘗試了回調和承諾的每一個組合，但不能讓它工作。你能看到我做錯了什麼嗎？

angular.module('app').controller('flQuestionCrudCtrl',function(flConstructDataService, flQuestionDataService, flQuestionCrud, flCachedReferenceData,flCachedQuestions, flAnswer, $scope, $location, $q, flIdentity, flNotifier,$timeout, $state) { 


$scope.createQuestion = function() { 

function doWorkAsync() { 
    return $timeout(flQuestionCrud.createNewQuestion(currentQuestionData), 10); 
} 

doWorkAsync() 
    .then(function(data) { 
     console.log("flQuestionCrudCtrl - Success " + data); 
     console.log("flQuestionCrudCtrl - Success Statement " + data.statement); 
     console.log("flQuestionCrudCtrl - Success Question id " + data._id); 
     currentQuestionData._id = data._id; 
     flQuestionDataService.setNewQuestionId(data._id); 
     console.log("flQuestionCrudCtrl - currentQuestionData._id " + currentQuestionData._id); 
     console.log("flQuestionCrudCtrl - flQuestionDataService.getNewQuestionId() " + flQuestionDataService.getNewQuestionId()); 
     $state.go('questionUpdate'); 
    }) 
    .catch(function(err) { 
     console.log("flQuestionCrudCtrl - Error " + err); 
     $state.go('questionCreate'); 
    }) 
    .finally(); 
}; 

} 


angular.module('app').factory('flQuestionCrud',function($http, $q, $state, $timeout, flQuestion){ 
    return { 
     createNewQuestion: function(newQuestionData) { 
      console.log("Before - flQuestion.create"); 

     function createQuestionDataAsync(questionData) { 
      console.log("flQuestionCrud - Before Call to create ") 
      var returnData; 
      flQuestion.create(questionData, function(data) { 
       console.log("flQuestionCrud - After Call to create ") 
       if (!data){ 
        return Error("Error Creating Data"); 
        //return null; 
       } 
       else { 
        console.log("flQuestionCrud - Try Section - Success " + data); 
        console.log("flQuestionCrud - Try Section - Success Statement " + data.statement); 
        console.log("flQuestionCrud - Try Section - Success Question id " + data._id); 
       } 
       return data; 
      }); 
     } 

     createQuestionDataAsync(newQuestionData); 
    }, 

Answer 1

你flQuestionCrud.createNewQuestion()方法應該返回與data解決的承諾：

angular.module('app') 
    .factory('flQuestionCrud', function($http, $q, $state, $timeout, flQuestion){ 
     return { 
      createNewQuestion: function(newQuestionData) { 
       var deferred = $q.defer(); 

       flQuestion.create(questionData, function(data) { 
        if (data){ 
         // whatever we resolve the promise with will be passed 
         // to the `then` handler in the controller 
         deferred.resolve(data); 
        } 
        else { 
         deferred.reject("Error Creating Data"); 
        } 
       }); 

       return deferred.promise; 
      } 
      // ... 
     } 
    }); 

注意，我們要明確地建立的承諾和解決或拒絕它取決於什麼flQuestion.create()回報。

這樣你就可以訪問你的控制器data你做的方式：

flQuestionCrud.createNewQuestion(currentQuestionData) 
    .then(function(data) { 
     // work with data here 
    }); 

或

doWorkAsync() 
    .then(function(data) { 
     // work with data here 
    });