Angular ngChange 处理程序获取旧值

Question

我正在创建 angular 指令，它用 bootstrap 表单组包装 html 输入。我使用 ng-change 事件来监听变化，但是我在 ng-change handler.To 中得到了旧值显示这个，我创建了相同的指令，一个使用 ng-keyup 而另一个使用 ng-change 事件来监听变化.

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 textNgChangeChanged 处理程序中的值尚未更新。

这是设计使然吗？我该如何解决这个问题？

Answer 1

看起来当使用 Primative 类型作为 ng-model 值时，ng-change 将在值更改时调用。由于这是原始类型，因此该值尚未传播到 homeCtroller。如果您向指令传递一个引用对象，事情就会按预期进行。

通过引用传递文本

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>

通过 val 传递文本

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>

Angular ngChange 处理程序获取旧值

Angular ngChange handler gets old value

angularjs

angular-ngmodel

通过引用传递文本

通过 val 传递文本