AngularJS Select Boxes
AngularJS lets you create dropdown lists based on items in an array, or an object.
Creating a Select Box Using ng-options
If you want to create a dropdown list, based on an object or an array in AngularJS, you should use the ng-options directive:
Example
<div ng-app="myApp" ng-controller="myCtrl">
<select ng-model="selectedName"
ng-options="x for x in names">
</select>
</div>
<script>
var app = angular.module('myApp', []);
app.controller('myCtrl',
function($scope) {
$scope.names = ["Emil", "Tobias",
"Linus"];
});
</script>
Try it Yourself »
ng-options vs ng-repeat
You can also use the ng-repeat directive to make the same dropdown list:
Because the ng-repeat directive repeats a block of HTML code for
each item in an array, it can be used to create options in a dropdown list, but
the ng-options directive was made especially for filling a dropdown
list with options, and has at least one important advantage:
Dropdowns made with ng-options allows the selected value to be
an object, while dropdowns made from ng-repeat has
to be a string.
What Do I Use?
Assume you have an array of objects:
$scope.cars = [
{model : "Ford Mustang", color :
"red"},
{model : "Fiat 500", color : "white"},
{model : "Volvo XC90", color : "black"}
];
The ng-repeat directive has its limitations, the selected value must be a string:
Example
Using ng-repeat:
<select ng-model="selectedCar">
<option ng-repeat="x in cars" value="{{x.model}}">{{x.model}}</option>
</select>
<h1>You selected: {{selectedCar}}</h1>
Try it Yourself »
When using the ng-options directive, the selected value can be an object:
Example
Using ng-options:
<select ng-model="selectedCar" ng-options="x.model for x in cars">
</select>
<h1>You selected: {{selectedCar.model}}</h1>
<p>Its color is: {{selectedCar.color}}</p>
Try it Yourself »
When the selected value can be an object, it can hold more information, and your application can be more flexible.
We will use the ng-options directive in this tutorial.
The Data Source as an Object
In the previous examples the data source was an array, but we can also use an object.
Assume you have an object with key-value pairs:
$scope.cars = {
car01 : "Ford",
car02 : "Fiat",
car03 : "Volvo"
};
The expression in the ng-options attribute is a bit different
for objects:
Example
Using an object as the data source, x represents the key, and
y
represents the value:
<select ng-model="selectedCar" ng-options="x for (x, y) in cars">
</select>
<h1>You selected: {{selectedCar}}</h1>
Try it Yourself »
The selected value will always be the value in a key-value pair.
The value in a key-value pair can also be an object:
Example
The selected value will still be the value in a key-value pair, only this time it is an object:
$scope.cars = {
car01 : {brand : "Ford", model : "Mustang", color :
"red"},
car02 : {brand : "Fiat", model : "500", color : "white"},
car03 : {brand : "Volvo", model : "XC90", color : "black"}
};
Try it Yourself »
The options in the dropdown list does not have to be the key in a key-value pair, it can also be the value, or a property of the value object:
Example
<select ng-model="selectedCar" ng-options="y.brand for (x, y) in cars">
</select>
Try it Yourself »
