從JSON對象數組

Question

這裏返回特定的對象是我services.js是什麼樣子：

var app = angular.module('starter.services', []) 


    .factory('Studies',function($http,$filter){ 
     var studies = []; 
     $http.get("studies.json").success(
       function(data){ 
        //studies = data; 
        angular.copy(data, studies); 
       } 
      ); 
     single_object = $filter('filter')(studies, function (d) {return d.nodeRef === "56e3382b-9a76-48ee-9c14-907e71b7a184";})[0]; 
     console.log(single_object); 
     return { 
     all: function(){ 
      return studies; 
     } 
    }; 
    }) 

所以你可以看到我做這包含屬性「nodeRef」對象JSON文件的GET請求恰好是一個屬性。我想根據它的noderef匹配過濾掉一個特定的對象。目前console.log返回「未定義」我想這可能是因爲它在json文件被加載之前被調用。如果有人能提供解決方案，我將非常感激。

Answer 1

您正在執行異步請求並在服務器的響應之前觸發過濾器，因此您得到undefined的原因是因爲此時您正在將過濾器應用於空數組。

你應該將你的過濾器調用success塊內，使它的工作，只要你想：

VAR應用= angular.module（ 'starter.services'，[]）

.factory('Studies',function($http,$filter){ 
    var studies = []; 
    $http.get("studies.json").success(
      function(data){ 
       //studies = data; 
       angular.copy(data, studies); 
       single_object = filter("56e3382b-9a76-48ee-9c14-907e71b7a184"); 
       console.log(single_object); 
      } 
     ); 
    function filter(node) { 
    if (studies.length > 0) { 
     return $filter('filter')(studies, function (d) {return d.nodeRef === node;})[0]; 
    } 
    } 
    return { 
    all: function(){ 
     return studies; 
    }, 
    filtered: filter 
}; 
}) 

Answer 2

你是正確的控制檯顯示「未定義」，因爲在ajax請求尚未填充研究。移動過濾器和控制檯登錄到.success功能：也

$http.get("studies.json").success(
      function(data){ 
       //studies = data; 
       angular.copy(data, studies); 
       single_object = $filter('filter')(studies, function (d) {return d.nodeRef === "56e3382b-9a76-48ee-9c14-907e71b7a184";})[0]; 
       console.log(single_object); 
      } 
     ); 

，我想你需要一個承諾這裏更新研究它完成時。退出Angular $q

您將返回承諾，然後在$ http.success函數中解析它，如下所示： var deferred = $ q.defer（）; .factory（ '研究'，函數（$ HTTP，$ Q，$過濾器）{

var studies = []; 
    $http.get("studies.json").success(
      function(data){ 
       //studies = data; 
       angular.copy(data, studies); 
       //At this point you can filter data as required, or not at all. I would suggest returning the entire JSON response and not filtering here at all, let the controllers filter the data as needed to maintain a layer of separation between controller and service. 

       deferred.resolve(studies); 
      } 
     ); 

    return { 
    all: function(){ 
     return deferred.promise; 
    } 
}; 
//In your controller, or wherever else... 
Studies.all().then(function(studies){ //this will fire when everything is all done. The studies variable is a full JSON object returned from the server (See deferred.resolve() in the service class). Filter here accordingly: 
$scope.studies = $filter('filter')(studies, function (d) {return d.nodeRef === "56e3382b-9a76-48ee-9c14-907e71b7a184";})[0]; 
})