AngularJS: $watch for a select input

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I know we can use ng-change to solve this but I would like to understand why $watch doesn\'twork on select. Maybe I\'m doingsomething wrong but it seems I am not the only on

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2条回答

耶瑟儿～

2021-01-20 15:25

For make it working you need to do number of changes in your code, You need to put all server related information to one object named as self.serverInfo that will contain the information about server & servers directly bind this with scope variable will update binding automatically as per JavaScript Prototypal inheritance.

HTML

<body ng-controller="SettingsCtrl">
  <div class="list">
    <label class="item item-input item-select">
      <div class="input-label">
        Server
      </div>
      {{serverInfo}}
      <select ng-model="serverInfo.server" 
      ng-options="s as s.label for s in serverInfo.servers">
      </select>
    </label>
  </div>
</body>

Controller

var app = angular.module('app',[]);

app.controller('SettingsCtrl', function ($scope, $log, serverSelection) {

    //List of servers to connect to
    $scope.serverInfo= serverSelection.serverInfo;
    $scope.$watch('serverInfo.server', function(NewValue, OldValue) {
        $scope.url = $scope.serverInfo.server.url;
    }, true);

})

app.service("serverSelection", function() {
    var self = this;
    self.serverInfo = {};
    self.serverInfo.servers = [
        { label: 'Production', value: 1, url: 'url1' },
        { label: 'Training', value: 2, url: 'url2' },
        { label: 'Local', value: 3, url: 'url2' }
    ];

    self.serverInfo.server = self.serverInfo.servers[1];
    console.log(self.server);
    self.serverInfo.url = self.serverInfo.server.url;

})

Working Plunkr

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粉色の甜心

2021-01-20 15:29

I accept answer from @pankajparkar but I'd like to show my final code as in fact with the proper binding proposed by @pankajparkar I don't need a $watch anymore.

HTML

    <div class="list">
        <label class="item item-input item-select">
            <div class="input-label">
                Serveur
            </div>
            <select ng-model="serverSelection.server" ng-options="s as s.label for s in serverSelection.servers">
            </select>
        </label>
    </div>
    <p>URL: {{serverSelection.server.url}}</p>

.controller('SettingsCtrl', function ($scope, $log, serverSelection) {

    //List of servers to connect to
    $scope.serverSelection= serverSelection;

})


.service("serverSelection", function() {
    var self = this;

    self.servers = [
        { label: 'Production', value: 1, url: 'url0' },
        { label: 'Training', value: 2, url: 'url1' },
        { label: 'Local', value: 3, url: 'url2' }
    ];

    self.server = self.servers[1];

})

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