openmct/platform/commonUI/general/src/controllers/GetterSetterController.js
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JavaScript

/*****************************************************************************
* Open MCT Web, Copyright (c) 2014-2015, United States Government
* as represented by the Administrator of the National Aeronautics and Space
* Administration. All rights reserved.
*
* Open MCT Web is licensed under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0.
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
* Open MCT Web includes source code licensed under additional open source
* licenses. See the Open Source Licenses file (LICENSES.md) included with
* this source code distribution or the Licensing information page available
* at runtime from the About dialog for additional information.
*****************************************************************************/
/*global define*/
define(
[],
function () {
"use strict";
/**
* This controller acts as an adapter to permit getter-setter
* functions to be used as ng-model arguments to controls,
* such as the input-filter. This is supported natively in
* Angular 1.3+ via `ng-model-options`, so this controller
* should be made obsolete after any upgrade to Angular 1.3.
*
* It expects to find in scope a value `ngModel` which is a
* function which, when called with no arguments, acts as a
* getter, and when called with one argument, acts as a setter.
*
* It also publishes into the scope a value `getterSetter.value`
* which is meant to be used as an assignable expression.
*
* This controller watches both of these; when one changes,
* it will update the other's value to match. Because of this,
* the `ngModel` function should be both stable and computationally
* inexpensive, as it will be invoked often.
*
* Getter-setter style models can be preferable when there
* is significant indirection between templates; "dotless"
* expressions in `ng-model` can behave unexpectedly due to the
* rules of scope, but dots are lost when passed in via `ng-model`
* (so if a control is internally implemented using regular
* form elements, it can't transparently pass through the `ng-model`
* parameter it received.) Getter-setter functions are never the
* target of a scope assignment and so avoid this problem.
*
* @memberof platform/commonUI/general
* @constructor
* @param {Scope} $scope the controller's scope
*/
function GetterSetterController($scope) {
// Update internal assignable state based on changes
// to the getter-setter function.
function updateGetterSetter() {
if (typeof $scope.ngModel === 'function') {
$scope.getterSetter.value = $scope.ngModel();
}
}
// Update the external getter-setter based on changes
// to the assignable state.
function updateNgModel() {
if (typeof $scope.ngModel === 'function') {
$scope.ngModel($scope.getterSetter.value);
}
}
// Watch for changes to both expressions
$scope.$watch("ngModel()", updateGetterSetter);
$scope.$watch("getterSetter.value", updateNgModel);
// Publish an assignable field into scope.
$scope.getterSetter = {};
}
return GetterSetterController;
}
);