Andrej Kaurin Andrej Kaurin - 4 months ago 32
Javascript Question

Working with select using Angular's ng-options

I have read about it in other posts but couldn't figure out.
I have array:

$scope.items = [
{ID: '000001', Title: 'Chicago'},
{ID: '000002', Title: 'New York'},
{ID: '000003', Title: 'Washington'},
];


I want to render this

<select>
<option value="000001">Chicago</option>
<option value="000002">New York</option>
<option value="000003">Washington</option>
</select>


And also I want to select option with ID=000002.

I have read this http://docs.angularjs.org/api/ng.directive:select and tried but can't figure out.

Answer

One thing to note is that ngModel is required for ngOptions to work... note the ng-model="blah" which is saying "set $scope.blah to the selected value".

Try this:

<select ng-model="blah" ng-options="item.ID as item.Title for item in items"></select>

Here's more from Angular's documentation (if you haven't seen it):

for array data sources:

  • label for value in array
  • select as label for value in array
  • label group by group for value in array = select as label group by group for value in array

for object data sources:

  • label for (key , value) in object
  • select as label for (key , value) in object
  • label group by group for (key, value) in object
  • select as label group by group for (key, value) in object

EDIT: For some clarification on option tag values in Angular

When you use ng-options, the values of option tags written out by ng-options will always be the index of the array item the option tag relates to. This is because Angular actually allows you to select entire objects with select controls, and not just primitive types. For example:

app.controller('MainCtrl', function($scope) {
   $scope.items = [
     { id: 1, name: 'foo' },
     { id: 2, name: 'bar' },
     { id: 3, name: 'blah' }
   ];
});
<div ng-controller="MainCtrl">
   <select ng-model="selectedItem" ng-options="item as item.name for item in items"></select>
   <pre>{{selectedItem | json}}</pre>
</div>

The above will allow you to select an entire object into $scope.selectedItem directly. The point is, with Angular, you don't need to worry about what's in your option tag. Let Angular handle that, you should only care about what's in your model in your scope.

Here is a plunker demonstrating the behavior above, and showing the html written out


EDIT 2: Dealing with the default option:

There are a few things I've failed to mention above relating to the default option.

Selecting first option and removing the empty option:

You can do this by adding a simple ng-init that sets the model (from ng-model) to the first element in the items your repeating in ng-options:

<select ng-init="foo = foo || items[0]" ng-model="foo" ng-options="item as item.name for item in items"></select>

Note: this could get a little crazy if foo happens to be initialized properly to something "falsy". In that case, you'll want to handle the initialization of foo in your controller, most likely.

Customizing the default option:

This is a little different, here all you need to do is add an option tag as a child of your select, with an empty value attribute, then customize it's inner text:

<select ng-model="foo" ng-options="item as item.name for item in items">
   <option value="">Nothing selected</option>
</select>

Note: that in this case the "empty" option will stay there even after you select a different option. This isn't the case for the default behavior of selects under Angular.

A customized default option that hides after a selection is made:

If you wanted your customized default option to go away after you select a value, you can add an ng-hide attribute to your default option:

<select ng-model="foo" ng-options="item as item.name for item in items">
   <option value="" ng-if="foo">Select something to remove me.</option>
</select>
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