Angular ngChange 处理程序获取旧值 [英] Angular ngChange handler gets old value
问题描述
我正在创建 angular 指令，它用引导程序表单组包装 html 输入.我使用 ng-change 事件来监听更改，但我在 ng-change 处理程序中获得了旧值.为了说明这一点，我创建了相同的指令，一个使用 ng-keyup，另一个使用 ng-change 事件来监听更改.
I am creating angular directive, which wraps html input with bootstrap form group. I use ng-change event to listen to changes, but I get old value inside ng-change handler.To show this, I created to identical directives, one uses ng-keyup and another uses ng-change event to listen to changes.
var app = angular.module('app', []);
app.controller('home', function() {
this.textKeyUp = 'KeyUp';
this.textNgChange = 'NgChange';
this.textKeyUpChanged = function() {
console.log('Changed on KeyUp:', this.textKeyUp);
};
this.textNgChangeChanged = function() {
console.log('Changed on NgChange:', this.textNgChange);
};
});
app.directive('apTextKeyUp', function() {
return {
controller: function() {},
controllerAs: 'ctrl',
bindToController: {
model: '=',
change: '&'
},
scope: {},
template: '<input ng-model="ctrl.model" ng-keyup="ctrl.change()" />'
};
});
app.directive('apTextNgChange', function() {
return {
controller: function() {},
controllerAs: 'ctrl',
bindToController: {
model: '=',
change: '&'
},
scope: {},
template: '<input ng-model="ctrl.model" ng-change="ctrl.change()" />'
};
});<!DOCTYPE html>
<html ng-app="app">
<head>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.5/angular.min.js"></script>
</head>
<body ng-controller="home as ctrl">
<h3>KeyUp</h3>
<ap-text-key-up model="ctrl.textKeyUp" change="ctrl.textKeyUpChanged()"></ap-text-key-up>
<h3>NgChange</h3>
<ap-text-ng-change model="ctrl.textNgChange" change="ctrl.textNgChangeChanged()"></ap-text-ng-change>
</body>
</html>两个指令都更新模型值，但内部 textNgChangeChanged 处理程序值尚未更新.
Both directives update model value, but inside textNgChangeChanged handler value is not updated yet.
这是故意的吗?我该如何解决这个问题?
Is this by design? How can I fix this problem?
推荐答案
看起来当使用 Primative 类型作为 ng-model 值时，当值改变时会调用 ng-change.由于这是原始类型，因此该值尚未传播到 homeCtroller.如果您将指令传递给一个引用对象，那么事情会按预期工作.
It looks like when using Primative type as the ng-model value, ng-change will be invoke when the value is changed. Since this is a primative type, the value hasn't been propagated to the homeCtroller. If you pass the directive a reference object, things work as expected.
var app = angular.module('app', []);
app.controller('home', function() {
this.text = {val: 'ABC'};
this.textChanged = function() {
console.log('Changed:', this.text.val);
};
});
app.directive('apText', function() {
return {
controller: function() {
var vm = this;
vm.onChange = function(){
console.log(vm.model);
vm.change();
};
},
controllerAs: 'ctrl',
bindToController: {
model: '=',
change: '&'
},
scope: true,
template: '<input ng-model="ctrl.model.val" ng-change="ctrl.onChange()" />'
};
});<!DOCTYPE html>
<html ng-app="app">
<head>
<link rel="stylesheet" href="style.css" />
<script src="https://code.angularjs.org/1.5.0-rc.0/angular.js"></script>
<script src="script.js"></script>
</head>
<body ng-controller="home as ctrl">
<ap-text model="ctrl.text" change="ctrl.textChanged()"></ap-text>
</body>
</html>var app = angular.module('app', []);
app.controller('home', function() {
this.text = 'ABC';
this.textChanged = function() {
console.log('Changed:', this.text);
};
});
app.directive('apText', function() {
return {
controller: function() {
var vm = this;
vm.onChange = function(){
console.log(vm.model);
vm.change();
};
},
controllerAs: 'ctrl',
bindToController: {
model: '=',
change: '&'
},
scope: true,
template: '<input ng-model="ctrl.model" ng-change="ctrl.onChange()" />'
};
});<!DOCTYPE html>
<html ng-app="app">
<head>
<link rel="stylesheet" href="style.css" />
<script src="https://code.angularjs.org/1.5.0-rc.0/angular.js"></script>
<script src="script.js"></script>
</head>
<body ng-controller="home as ctrl">
<ap-text model="ctrl.text" change="ctrl.textChanged()"></ap-text>
</body>
</html>这篇关于Angular ngChange 处理程序获取旧值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
