我有一个服务，说:
factory('aService', ['$rootScope', '$resource', function ($rootScope, $resource) {
var service = {
foo: []
};
return service;
}]);
我想用foo来控制一个在HTML中呈现的列表:
<div ng-controller="FooCtrl">
<div ng-repeat="item in foo">{{ item }}</div>
</div>
以便控制器检测aService。我已经拼凑了这个模式，其中我添加aService到控制器的$scope，然后使用$scope.$watch():
function FooCtrl($scope, aService) {
$scope.aService = aService;
$scope.foo = aService.foo;
$scope.$watch('aService.foo', function (newVal, oldVal, scope) {
if(newVal) {
scope.foo = newVal;
}
});
}
这感觉有点冗长，我一直在每个使用服务变量的控制器中重复这一点。有没有更好的方法来监视共享变量?
我在另一个线程上找到了一个非常好的解决方案，有类似的问题，但方法完全不同。当$rootScope值被改变时，$watch within指令将无法正常工作
基本上解决方案告诉不要使用$watch，因为它是非常沉重的解决方案。相反，他们建议使用$emit和$on。
我的问题是在我的服务中观察一个变量并在指令中做出反应。用上面的方法就很简单了!
我的模块/服务示例:
angular.module('xxx').factory('example', function ($rootScope) {
var user;
return {
setUser: function (aUser) {
user = aUser;
$rootScope.$emit('user:change');
},
getUser: function () {
return (user) ? user : false;
},
...
};
});
所以基本上我观察我的用户-每当它被设置为新值时I $emit一个user:change status。
在我的例子中，在我使用的指令中:
angular.module('xxx').directive('directive', function (Auth, $rootScope) {
return {
...
link: function (scope, element, attrs) {
...
$rootScope.$on('user:change', update);
}
};
});
现在在指令中，我监听$rootScope和给定的更改-我分别做出反应。非常简单和优雅!
有点丑，但我已经为切换添加了范围变量的注册到我的服务:
myApp.service('myService', function() {
var self = this;
self.value = false;
self.c2 = function(){};
self.callback = function(){
self.value = !self.value;
self.c2();
};
self.on = function(){
return self.value;
};
self.register = function(obj, key){
self.c2 = function(){
obj[key] = self.value;
obj.$apply();
}
};
return this;
});
然后在控制器中:
function MyCtrl($scope, myService) {
$scope.name = 'Superhero';
$scope.myVar = false;
myService.register($scope, 'myVar');
}
这是我的一般方法。
mainApp.service('aService',[function(){
var self = this;
var callbacks = {};
this.foo = '';
this.watch = function(variable, callback) {
if (typeof(self[variable]) !== 'undefined') {
if (!callbacks[variable]) {
callbacks[variable] = [];
}
callbacks[variable].push(callback);
}
}
this.notifyWatchersOn = function(variable) {
if (!self[variable]) return;
if (!callbacks[variable]) return;
angular.forEach(callbacks[variable], function(callback, key){
callback(self[variable]);
});
}
this.changeFoo = function(newValue) {
self.foo = newValue;
self.notifyWatchersOn('foo');
}
}]);
在控制器中
function FooCtrl($scope, aService) {
$scope.foo;
$scope._initWatchers = function() {
aService.watch('foo', $scope._onFooChange);
}
$scope._onFooChange = function(newValue) {
$scope.foo = newValue;
}
$scope._initWatchers();
}
FooCtrl.$inject = ['$scope', 'aService'];
你可以在$rootScope中插入服务，然后观察:
myApp.run(function($rootScope, aService){
$rootScope.aService = aService;
$rootScope.$watch('aService', function(){
alert('Watch');
}, true);
});
在你的控制器中:
myApp.controller('main', function($scope){
$scope.aService.foo = 'change';
});
另一个选择是使用外部库，例如:https://github.com/melanke/Watch.JS
"发射架:IE +， f4 +，稳定基金5+
您可以观察一个、多个或所有对象属性的变化。
例子:
var ex3 = {
attr1: 0,
attr2: "initial value of attr2",
attr3: ["a", 3, null]
};
watch(ex3, function(){
alert("some attribute of ex3 changes!");
});
ex3.attr3.push("new value");
= = = =更新
在$watch中非常简单。
笔在这里。
HTML:
<div class="container" data-ng-app="app">
<div class="well" data-ng-controller="FooCtrl">
<p><strong>FooController</strong></p>
<div class="row">
<div class="col-sm-6">
<p><a href="" ng-click="setItems([ { name: 'I am single item' } ])">Send one item</a></p>
<p><a href="" ng-click="setItems([ { name: 'Item 1 of 2' }, { name: 'Item 2 of 2' } ])">Send two items</a></p>
<p><a href="" ng-click="setItems([ { name: 'Item 1 of 3' }, { name: 'Item 2 of 3' }, { name: 'Item 3 of 3' } ])">Send three items</a></p>
</div>
<div class="col-sm-6">
<p><a href="" ng-click="setName('Sheldon')">Send name: Sheldon</a></p>
<p><a href="" ng-click="setName('Leonard')">Send name: Leonard</a></p>
<p><a href="" ng-click="setName('Penny')">Send name: Penny</a></p>
</div>
</div>
</div>
<div class="well" data-ng-controller="BarCtrl">
<p><strong>BarController</strong></p>
<p ng-if="name">Name is: {{ name }}</p>
<div ng-repeat="item in items">{{ item.name }}</div>
</div>
</div>
JavaScript:
var app = angular.module('app', []);
app.factory('PostmanService', function() {
var Postman = {};
Postman.set = function(key, val) {
Postman[key] = val;
};
Postman.get = function(key) {
return Postman[key];
};
Postman.watch = function($scope, key, onChange) {
return $scope.$watch(
// This function returns the value being watched. It is called for each turn of the $digest loop
function() {
return Postman.get(key);
},
// This is the change listener, called when the value returned from the above function changes
function(newValue, oldValue) {
if (newValue !== oldValue) {
// Only update if the value changed
$scope[key] = newValue;
// Run onChange if it is function
if (angular.isFunction(onChange)) {
onChange(newValue, oldValue);
}
}
}
);
};
return Postman;
});
app.controller('FooCtrl', ['$scope', 'PostmanService', function($scope, PostmanService) {
$scope.setItems = function(items) {
PostmanService.set('items', items);
};
$scope.setName = function(name) {
PostmanService.set('name', name);
};
}]);
app.controller('BarCtrl', ['$scope', 'PostmanService', function($scope, PostmanService) {
$scope.items = [];
$scope.name = '';
PostmanService.watch($scope, 'items');
PostmanService.watch($scope, 'name', function(newVal, oldVal) {
alert('Hi, ' + newVal + '!');
});
}]);
