AngularJS监视服务对象

问题描述

为什么我不能观看服务中的对象.香港专业教育学院有一个简单的变量工作，但一个对象将无法工作. http://plnkr.co/edit/S4b2g3baS7dwQt3t8XEK?p=preview

Why can't I watch a object in a service.Ive got a simple variable working, but a object wont work.http://plnkr.co/edit/S4b2g3baS7dwQt3t8XEK?p=preview

var app = angular.module('plunker', []);

app.service('test', ['$http', '$rootScope',
            function ($http,   $rootScope) {

  var data = 0;
  var obj  = {
                "data": 0
              };

  this.add = function(){
    obj.data += 1;
    console.log('data:', obj);
  };

  this.getData     = function() { return obj; };

}]);

app.controller('TestController', ['$scope', '$rootScope', '$filter', 'test',
                          function($scope,   $rootScope,   $filter,   test) {

  //test controller
  $scope.add = function(){
    test.add();
  };
  $scope.test = test;
  $scope.$watch('test.getData()', function(newVal){
    console.log('data changes into: ', newVal)
  });
}]);

推荐答案

您需要将true作为$ watch函数的最后一个参数传递，以使相等性检查为angular.equals.否则，仅检查引用相等性.

You need to pass true as the last parameter of the $watch function so that the equality check is angular.equals. Otherwise only reference equality is checked.

$scope.$watch('test.getData()', function(newVal){
  console.log('data changes into: ', newVal)
}, true);

重复的问题: $观看对象

编辑

正如下面提到的，该代码包含一个不好的做法–在$scope中引用了服务.不必在范围内引用它，因为$watch还接受getter函数作为第一个参数.干净的解决方案使用此函数按下面的答案中的方式返回监视的数组. $scope.$watch(function() { return test.getData(); } ...

As mentioned bellow, the code includes a bad practice – having a service referenced in $scope. It is not necessary to reference it in scope, since $watch also accepts a getter function as first argument. Clean solution uses this function to return the watched array as is in the answer below. $scope.$watch(function() { return test.getData(); } ...

要列出完整的解决方案，您还可以使用$watchCollection来解决引用相等性检查问题.

To list a complete solution you could also use $watchCollection instead to solve the reference equality check problem.

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