Angular Checkboxes “Select All” functionality with only one box selected initially

问题

I have a form that contains 3 checkboxes: "Select All", "Option 1", and "Option 2".

<form id="selectionForm">
    <input type="checkbox" ng-model="selectAll" >Select all
    <br>
    <input type="checkbox" ng-checked="selectAll" checked>Option 1
    <br>
    <input type="checkbox" ng-checked="selectAll">Option 2
</form>

On the initial page load I want only Option 1 to be checked. And then if the Select All checkbox gets checked it should automatically check Option 1 and Option 2 so all are selected.

The problem is on the initial page load the ng-checked="selectAll" gets evaluated which overrides my attempt to initially check only Option 1 (selectAll = false initially), so nothing is selected.

This seems like a simple problem to solve, but I can't figure out a solution... Thanks in advance for any insights or advice!

回答1:

Another way to go about it is to use a model for the options, set default selection in the model and have your controller handle the logic of doing select all.

angular.module("app", []).controller("ctrl", function($scope){
  
  $scope.options = [
    {value:'Option1', selected:true}, 
    {value:'Option2', selected:false}
  ];
  
  $scope.toggleAll = function() {
     var toggleStatus = !$scope.isAllSelected;
     angular.forEach($scope.options, function(itm){ itm.selected = toggleStatus; });
   
  }
  
  $scope.optionToggled = function(){
    $scope.isAllSelected = $scope.options.every(function(itm){ return itm.selected; })
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js">    </script>
<div ng-app="app" ng-controller="ctrl">
<form id="selectionForm">
    <input type="checkbox" ng-click="toggleAll()" ng-model="isAllSelected">Select all
    <br>
     <div ng-repeat = "option in options">
        <input type="checkbox" ng-model="option.selected" ng-change="optionToggled()">{{option.value}}
     </div>
</form>
  {{options}} 
</div>

回答2:

I like to use an ng-repeat for clarity on showing what you're selecting/un-selecting, basically you end up with a nice little object to base it all on, and adding to it is just easier.

Here's a Plunker

*Also notice how you can achieve allSelected? with a loop func and not a ton of html, and I'm sure this can be done with less spaghetti but it works *

app.controller('MainCtrl', function($scope) {

$scope.allSelected = false;

$scope.checkboxes = [{label: 'Option 1',checked: true}, {label: 'Option 2'}}}];

$scope.cbChecked = function(){
  $scope.allSelected = true;
  angular.forEach($scope.checkboxes, function(v, k) {
    if(!v.checked){
      $scope.allSelected = false;
    }
  });
}
$scope.toggleAll = function() {
    var bool = true;
    if ($scope.allSelected) {
      bool = false;
    }
    angular.forEach($scope.checkboxes, function(v, k) {
      v.checked = !bool;
      $scope.allSelected = !bool;
      });
   }
});

回答3:

Try this:

<form id="selectionForm">
    <input type="checkbox" ng-model="selectAll" >Select all
    <br>
    <input type="checkbox" ng-checked="selectAll || option1" ng-init="option1=true" ng-model="option1">Option 1
    <br>
    <input type="checkbox" ng-checked="selectAll">Option 2
</form>

来源：https://stackoverflow.com/questions/27451954/angular-checkboxes-select-all-functionality-with-only-one-box-selected-initial