angular.js - Why doesn't ng-change trigger when angular assigns a value to select?

Question

1. The HTML code is as follows:

<!-- 这个是街道 -->
<select name="jd" ng-model="wgy.jd" class="form-control input-sm" ng-options="jd.code as jd.label for jd in bmOfJd" ng-change="getSqBm(wgy.jd)">
    <option value="">--请选择--</option>
</select>
<!-- 这个是社区 -->
<select name="sq" ng-model="wgy.sq" class="form-control input-sm" ng-options="sq.code as sq.label for sq in bmOfSq">
   <option value="">--请选择--</option>
 </select>

2. The JS code is as follows:

//如果选择街道，去取出社区
$scope.getSqBm = function(jd){
        BmService.getXzqh(jd)
            .then(function(data){
                $scope.bmOfSq = data;
            });
    };

3. Question: Because this is common to the new page and the query page, when editing the page, I assign a value to the street wgy.jd, but this will not trigger the street ng-change. How can I trigger it? What about ng-change?

Answer 1

Thank you for your answers. I have found a way
That is to manually call the ng-change method getSqBm($scope.wgy.jd) after assigning a value to wgy.jd.
This way it will trigger the ng-change of the street! ! !
Here are detailed instructions

Answer 2

It’s better to use watch to do it. Use changes in observed data to trigger a certain method

Answer 3

http://stackoverflow.com/questions/14386570/getting-the-ng-object-selected-with-ng-change

Answer 4

HTML

<select ng-model="wgy.jd"
        ng-change="getSqBm()">
    <option value="">--请选择--</option>
    <option ng-repeat="jd in jds" value="{{jd.id}}">{{jd.name}}</option>
</select>
<select ng-model="wgy.sq">
    <option value="">--请选择--</option>
    <option ng-repeat="sq in sqs" value="{{sq.id}}">{{sq.name}}</option>
</select>

SCRIPT

angular.module('myApp', [])
        .controller('MyCtrl', function ($scope) {
            $scope.wgy = {
                jd: '',
                sq: ''
            }

            $scope.jds = [
                {
                    id: 1,
                    name: '街道1',
                    sq: [
                        {
                            id: 1,
                            name: '街道1-社区1'
                        },
                        {
                            id: 2,
                            name: '街道1-社区2'
                        }
                    ]
                },
                {
                    id: 2,
                    name: '街道2',
                    sq: [
                        {
                            id: 1,
                            name: '街道2-社区1'
                        },
                        {
                            id: 2,
                            name: '街道2-社区2'
                        }
                    ]
                }
            ];

            $scope.sqs = [];

            $scope.getSqBm = function(){
                if(!$scope.wgy.jd){
                    $scope.sqs = [];
                    return ;
                }

                $scope.sqs = $scope.jds.filter(function(jd){
                    return jd.id == $scope.wgy.jd;
                })[0].sq;
            }
        });