Angularjs disabling drop down - angularjs

Question

I have a ui in which based on the selection of one drop down another dropdown should be disabled. Both these dropdowns are generated using ng-repeat . Below is the code sample
<tr data-ng-repeat="abc in xyz.divisionViewList" >
<select
data-ng-model="abc.selectedAppRole"
ng-init="abc.selectedAppRole =abc.selectedAdRole"
id="{{abc.applicationId}}_{{abc.divisionId}}" name="{{abc.selectedAppRole}}">
<option value="null">Select/Deselect a role</option>
<option data-ng-repeat="roleDetail in abc.roleDetails" data-ng-selected="{{abc.adRole == abc.selectedAdRole}}"
value="{{abc.adRole}}"> {{abc.roleDesc}} </option>
</select>
</tr>
As this is a dynamic generated drop downs based on ng- repeat, i want to put validations based on selection on one drop down. Please let me know how can i put this validation so that i can disable and enable any dropdown based on selection of the other.
I am really stuck on this.

Answer 1

Use ng-disabled and use model value of one of the dropdowns to disable/enable the other.
Example app:
angular.module('app', []).controller('MyController', function($scope){
$scope.dropdownSelections = {};
$scope.dropdownA = [
{value: 1, label: 'Item A1'},
{value: 2, label: 'Item A2'},
{value: 3, label: 'Item A3'},
{value: 4, label: 'Item A4'}
];
$scope.dropdownB = [
{value: 1, label: 'Item B1'},
{value: 2, label: 'Item B2'},
{value: 3, label: 'Item B3'},
{value: 4, label: 'Item B4'}
];
$scope.dropdownC = [
{value: 1, label: 'Item C1'},
{value: 2, label: 'Item C2'},
{value: 3, label: 'Item C3'},
{value: 4, label: 'Item C4'}
];
});
Example template code:
<div ng-controller="MyController">
<div>Dropdown selections: {{dropdownSelections}}</div>
<div>
<legend>Dropdown A</legend>
<select name="A" id="A" ng-model="dropdownSelections.dropdowA" ng-options="item.value as item.label for item in dropdownA"></select>
</div>
<div>
<legend>Dropdown B</legend>
<select name="B" id="B" ng-model="dropdownSelections.dropdowB" ng-options="item.value as item.label for item in dropdownB" ng-disabled="dropdownSelections.dropdowA !== 2"></select>
</div>
<div>
<legend>Dropdown C</legend>
<select name="C" id="C" ng-model="dropdownSelections.dropdowC" ng-options="item.value as item.label for item in dropdownC" ng-disabled="dropdownSelections.dropdowB !== 3"></select>
</div>
</div>
DropdownB will be enabled when DropdownA has option 2 selected. DropdownC will be enabled when DropdownB has option 3 selected. Of course this is only basic example, the code is not perfect, but demonstrates the idea.
I've created working example in this JSFiddle.
More information about ng-disabled can be found in this doc.