最近使用到了ngOption实现下拉选择列表，由于需要实现分组等功能，百度了下没有太好的文章，就百度到一篇英文的帖子，按照其中的代码很顺利的搞定了。
本篇根据文中代码，详细讲述下如何实现下拉列表
下拉列表的简单使用
ng-option指令使用很简单，只需要绑定两个属性：
一个是ng-model用于获取选定的值；
另一个是ng-options用于确定下拉列表的元素数组。
<select ng-model="engineer.currentActivity" class="form-control" ng-options="act for act in activities"></select>
上面这条语句就是把选择的值与engineer.currentActivity进行双向数据绑定，然后列表中的选项是activities中的每一个值。数据如下：
$scope.engineer = {
name: "Dani",
currentActivity: "Fixing bugs"
};
$scope.activities =
[
"Writing code",
"Testing code",
"Fixing bugs",
"Dancing"
];
运行结果如：
为了美观一点，这里引用了bootstrap。
<html ng-app="myApp"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <script src="http://apps.bdimg.com/libs/angular.js/1.2.16/angular.min.js"></script> <link rel="stylesheet" href="http://apps.bdimg.com/libs/bootstrap/3.3.0/css/bootstrap.min.css"> <script src="http://apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script> <script src="http://apps.bdimg.com/libs/bootstrap/3.3.0/js/bootstrap.min.js"></script> </head> <body> <div ng-controller="EngineeringController" class="container"> <div class="col-md-12"> {{engineer.name}} is currently: {{ engineer.currentActivity}} </div> <div class="col-md-4"> <label for="name">Choose a new activity:</label> <select ng-model="engineer.currentActivity" class="form-control" ng-options="act for act in activities"> </select> </div> </div> <script type="text/javascript"> var myAppModule = angular.module("myApp",[]); myAppModule.controller("EngineeringController",["$scope",function($scope){ $scope.engineer = { name: "Dani", currentActivity: "Fixing bugs" }; $scope.activities = [ "Writing code", "Testing code", "Fixing bugs", "Dancing" ]; }]); </script> </body> </html>
复杂对象，自定义列表名称
有的时候下拉列表并不是单纯的字符串数组，可能是json对象，例如：
$scope.activities =
[
{ id: 1, type: "Work" , name: "Writing code" },
{ id: 2, type: "Work" , name: "Testing code" },
{ id: 3, type: "Work" , name: "Fixing bugs" },
{ id: 4, type: "Play" , name: "Dancing" }
];
这个时候，绑定的数据就必须是与这里面的格式相同的数据，比如直接复制其中一条：
$scope.engineer = {
name: "Dani" ,
currentActivity: {
id: 3,
type: "Work" ,
name: "Fixing bugs"
}
};
当然也可以直接指定成：
$scope.engineer = {currentActivity:activities[3]}
然后在指令中可以循环列表拼接处下拉框的名称
<select
ng-model = "engineer.currentActivity"
class="form-control"
ng-options = "a.name +' (' + a.type + ')' for a in activities" >
</select >
运行效果如：
全部的代码如下：
<html ng-app="myApp"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <script src="http://apps.bdimg.com/libs/angular.js/1.2.16/angular.min.js"></script> <link rel="stylesheet" href="http://apps.bdimg.com/libs/bootstrap/3.3.0/css/bootstrap.min.css"> <script src="http://apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script> <script src="http://apps.bdimg.com/libs/bootstrap/3.3.0/js/bootstrap.min.js"></script> </head> <body> <div ng-controller="EngineeringController" class="container"> <div class="col-md-12"> {{engineer.name}} is currently: {{ engineer.currentActivity}} </div> <div class="col-md-4"> <label for="name">Choose a new activity:</label> <select ng-model = "engineer.currentActivity" class="form-control" ng-options = "a.name +' (' + a.type + ')' for a in activities" > </select > </div> </div> <script type="text/javascript"> var myAppModule = angular.module("myApp",[]); myAppModule.controller("EngineeringController",["$scope",function($scope){ $scope.engineer = { name: "Dani" , currentActivity: { id: 3, type: "Work" , name: "Fixing bugs" } }; $scope.activities = [ { id: 1, type: "Work" , name: "Writing code" }, { id: 2, type: "Work" , name: "Testing code" }, { id: 3, type: "Work" , name: "Fixing bugs" }, { id: 4, type: "Play" , name: "Dancing" } ]; }]); </script> </body> </html>
实现下拉列表的分组
其实分组与前面的例子很像，只要把空间中的ng-options的值换成下面：
<select ng-model = "engineer.currentActivity"
class="form-control"
ng-options = "a.name group by a.type for a in activities" >
</select >
添加 group by 就会按照后面的值进行分组
全部代码：
<html ng-app="myApp"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <script src="http://apps.bdimg.com/libs/angular.js/1.2.16/angular.min.js"></script> <link rel="stylesheet" href="http://apps.bdimg.com/libs/bootstrap/3.3.0/css/bootstrap.min.css"> <script src="http://apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script> <script src="http://apps.bdimg.com/libs/bootstrap/3.3.0/js/bootstrap.min.js"></script> </head> <body> <div ng-controller="EngineeringController" class="container"> <div class="col-md-12"> {{engineer.name}} is currently: {{ engineer.currentActivity}} </div> <div class="col-md-4"> <label for="name">Choose a new activity:</label> <!-- <select ng-model = "engineer.currentActivity" class="form-control" ng-options = "a.name +' (' + a.type + ')' for a in activities" > </select > --> <select ng-model = "engineer.currentActivity" class="form-control" ng-options = "a.name group by a.type for a in activities" > </select > </div> </div> <script type="text/javascript"> var myAppModule = angular.module("myApp",[]); myAppModule.controller("EngineeringController",["$scope",function($scope){ $scope.engineer = { name: "Dani" , currentActivity: { id: 3, type: "Work" , name: "Fixing bugs" } }; $scope.activities = [ { id: 1, type: "Work" , name: "Writing code" }, { id: 2, type: "Work" , name: "Testing code" }, { id: 3, type: "Work" , name: "Fixing bugs" }, { id: 4, type: "Play" , name: "Dancing" } ]; }]); </script> </body> </html>
按照id进行标识
由于之前的ng-model相当于初始的时候给设定了一个值。当你选择一个下拉列表选项的时候，就会覆盖掉这个初始值。
所以更多的时候会使用一个id进行标识，这样在初始化赋值的时候，只需要设定一个id就可以了。
$scope.engineer = {
currentActivityId: 3
};
$scope.activities =
[
{ id: 1, type: "Work" , name: "Writing code" },
{ id: 2, type: "Work" , name: "Testing code" },
{ id: 3, type: "Work" , name: "Fixing bugs" },
{ id: 4, type: "Play" , name: "Dancing" }
];
指令可以写成下面的格式
<select
ng-model = "engineer.currentActivityId"
class="form-control"
ng-options = "a.id as a.name group by a.type for a in activities" >
</select >
通过 as 前面的值，就可以确定唯一的一个选项
全部代码如下：
<html ng-app="myApp"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <script src="http://apps.bdimg.com/libs/angular.js/1.2.16/angular.min.js"></script> <link rel="stylesheet" href="http://apps.bdimg.com/libs/bootstrap/3.3.0/css/bootstrap.min.css"> <script src="http://apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script> <script src="http://apps.bdimg.com/libs/bootstrap/3.3.0/js/bootstrap.min.js"></script> </head> <body> <div ng-controller="EngineeringController" class="container"> <div class="col-md-12"> current is: {{ engineer.currentActivityId}} </div> <div class="col-md-4"> <label for="name">Choose a new activity:</label> <select ng-model = "engineer.currentActivityId" class="form-control" ng-options = "a.id as a.name group by a.type for a in activities" > </select > </div> </div> <script type="text/javascript"> var myAppModule = angular.module("myApp",[]); myAppModule.controller("EngineeringController",["$scope",function($scope){ $scope.engineer = { currentActivityId: 3 }; $scope.activities = [ { id: 1, type: "Work" , name: "Writing code" }, { id: 2, type: "Work" , name: "Testing code" }, { id: 3, type: "Work" , name: "Fixing bugs" }, { id: 4, type: "Play" , name: "Dancing" } ]; }]); </script> </body> </html>
参考
Using ngOptions in AngularJS:http://odetocode.com/blogs/scott/archive/2013/06/19/using-ngoptions-in-angularjs.aspx