AngularJS數據

Question

之前指令裝載比方說，我加載一個變量爲$範圍與$ HTTP：

$http.get('/teachers/4').success(function(data){ 
    $scope.teacher = data; 
}); 

我的模板使用這樣的數據：

Teacher: {{teacher.name}} 
<students-view students="teacher.students"></students-view> 

這個指令可以加載之前老師完成加載，但我的指令有代碼取決於teacher.students陣列被加載：

app.directive('studentsView', function(){ 
    return { 
    scope: { students: '=' }, 
    controller: function($scope){ 
     _.each($scope.students, function(s){ 
     // this is not called if teacher loads after this directive 
     }); 
    } 
    }; 
}); 

我該如何得到我想要的行爲？我不想停止使用$ http，如果可能的話，我不希望爲範圍分配一個承諾。

Answer 1

使用手錶等待students可用。一旦可用，就調用取決於它的代碼，然後移除手錶。如果您希望每次更改students時都執行代碼，則可以跳過刪除手錶。

app.directive('studentsView', function(){ 
    return { 
    scope: { students: '=' }, 
    link: function($scope){ 
     var unwatch = $scope.$watch('students', function(newVal, oldVal){ 
     // or $watchCollection if students is an array 
     if (newVal) { 
      init(); 
      // remove the watcher 
      unwatch(); 
     } 
     }); 

     function init(){ 
     _.each($scope.students, function(s){ 
      // do stuff 
     }); 
     } 
    } 
    }; 
}); 

Answer 2

你可能需要做一些手錶上students知道什麼時候被更新，然後運行_.each當手表被觸發：

app.directive('studentsView', function(){ 
    return { 
    scope: { students: '=' }, 
    controller: function($scope){ 
     scope.$watch('students', function(newValue, oldValue) { 
     _.each($scope.students, function(s){ 
      // this is not called if teacher loads after this directive 
     });  
     }; 
    } 
    }; 
}); 

更多$watch：https://docs.angularjs.org/api/ng/type/$rootScope.Scope