How do I bind to list of checkbox values with AngularJS?

How do I bind to list of checkbox values with AngularJS?

I have a few checkboxes:



That I would like to bind to a list in my controller such that whenever a checkbox is changed the controller maintains a list of all the checked values, for example, [‘apple’, ‘pear’].
ng-model seems to only be able to bind the value of one single checkbox to a variable in the controller.
Is there another way to do it so that I can bind the four checkboxes to a list in the controller?

Solutions/Answers:

Solution 1:

There are two ways to approach this problem. Either use a simple array or an array of objects. Each solution has it pros and cons. Below you’ll find one for each case.


With a simple array as input data

The HTML could look like:

<label ng-repeat="fruitName in fruits">
  <input
    type="checkbox"
    name="selectedFruits[]"
    value="{{fruitName}}"
    ng-checked="selection.indexOf(fruitName) > -1"
    ng-click="toggleSelection(fruitName)"
  > {{fruitName}}
</label>

And the appropriate controller code would be:

app.controller('SimpleArrayCtrl', ['$scope', function SimpleArrayCtrl($scope) {

  // Fruits
  $scope.fruits = ['apple', 'orange', 'pear', 'naartjie'];

  // Selected fruits
  $scope.selection = ['apple', 'pear'];

  // Toggle selection for a given fruit by name
  $scope.toggleSelection = function toggleSelection(fruitName) {
    var idx = $scope.selection.indexOf(fruitName);

    // Is currently selected
    if (idx > -1) {
      $scope.selection.splice(idx, 1);
    }

    // Is newly selected
    else {
      $scope.selection.push(fruitName);
    }
  };
}]);

Pros: Simple data structure and toggling by name is easy to handle

Cons: Add/remove is cumbersome as two lists (the input and selection) have to be managed


With an object array as input data

The HTML could look like:

<label ng-repeat="fruit in fruits">
  <!--
    - Use `value="{{fruit.name}}"` to give the input a real value, in case the form gets submitted
      traditionally

    - Use `ng-checked="fruit.selected"` to have the checkbox checked based on some angular expression
      (no two-way-data-binding)

    - Use `ng-model="fruit.selected"` to utilize two-way-data-binding. Note that `.selected`
      is arbitrary. The property name could be anything and will be created on the object if not present.
  -->
  <input
    type="checkbox"
    name="selectedFruits[]"
    value="{{fruit.name}}"
    ng-model="fruit.selected"
  > {{fruit.name}}
</label>

And the appropriate controller code would be:

app.controller('ObjectArrayCtrl', ['$scope', 'filterFilter', function ObjectArrayCtrl($scope, filterFilter) {

  // Fruits
  $scope.fruits = [
    { name: 'apple',    selected: true },
    { name: 'orange',   selected: false },
    { name: 'pear',     selected: true },
    { name: 'naartjie', selected: false }
  ];

  // Selected fruits
  $scope.selection = [];

  // Helper method to get selected fruits
  $scope.selectedFruits = function selectedFruits() {
    return filterFilter($scope.fruits, { selected: true });
  };

  // Watch fruits for changes
  $scope.$watch('fruits|filter:{selected:true}', function (nv) {
    $scope.selection = nv.map(function (fruit) {
      return fruit.name;
    });
  }, true);
}]);

Pros: Add/remove is very easy

Cons: Somewhat more complex data structure and toggling by name is cumbersome or requires a helper method


Demo: http://jsbin.com/ImAqUC/1/

Solution 2:

A simple solution:

<div ng-controller="MainCtrl">
  <label ng-repeat="(color,enabled) in colors">
      <input type="checkbox" ng-model="colors[color]" /> {{color}} 
  </label>
  <p>colors: {{colors}}</p>
</div>

<script>
  var app = angular.module('plunker', []);

  app.controller('MainCtrl', function($scope){
      $scope.colors = {Blue: true, Orange: true};
  });
</script>

http://plnkr.co/edit/U4VD61?p=preview

Solution 3:

<input type='checkbox' ng-repeat="fruit in fruits"
  ng-checked="checkedFruits.indexOf(fruit) != -1" ng-click="toggleCheck(fruit)">

.

function SomeCtrl ($scope) {
    $scope.fruits = ["apple, orange, pear, naartjie"];
    $scope.checkedFruits = [];
    $scope.toggleCheck = function (fruit) {
        if ($scope.checkedFruits.indexOf(fruit) === -1) {
            $scope.checkedFruits.push(fruit);
        } else {
            $scope.checkedFruits.splice($scope.checkedFruits.indexOf(fruit), 1);
        }
    };
}

Solution 4:

Here’s a quick little reusable directive that seems to do what you’re looking to do. I’ve simply called it checkList. It updates the array when the checkboxes change, and updates the checkboxes when the array changes.

app.directive('checkList', function() {
  return {
    scope: {
      list: '=checkList',
      value: '@'
    },
    link: function(scope, elem, attrs) {
      var handler = function(setup) {
        var checked = elem.prop('checked');
        var index = scope.list.indexOf(scope.value);

        if (checked && index == -1) {
          if (setup) elem.prop('checked', false);
          else scope.list.push(scope.value);
        } else if (!checked && index != -1) {
          if (setup) elem.prop('checked', true);
          else scope.list.splice(index, 1);
        }
      };

      var setupHandler = handler.bind(null, true);
      var changeHandler = handler.bind(null, false);

      elem.bind('change', function() {
        scope.$apply(changeHandler);
      });
      scope.$watch('list', setupHandler, true);
    }
  };
});

Here’s a controller and a view that shows how you might go about using it.

<div ng-app="myApp" ng-controller='MainController'>
  <span ng-repeat="fruit in fruits">
    <input type='checkbox' value="{{fruit}}" check-list='checked_fruits'> {{fruit}}<br />
  </span>

  <div>The following fruits are checked: {{checked_fruits | json}}</div>

  <div>Add fruit to the array manually:
    <button ng-repeat="fruit in fruits" ng-click='addFruit(fruit)'>{{fruit}}</button>
  </div>
</div>
app.controller('MainController', function($scope) {
  $scope.fruits = ['apple', 'orange', 'pear', 'naartjie'];
  $scope.checked_fruits = ['apple', 'pear'];
  $scope.addFruit = function(fruit) {
    if ($scope.checked_fruits.indexOf(fruit) != -1) return;
    $scope.checked_fruits.push(fruit);
  };
});

(The buttons demonstrate that changing the array will also update the checkboxes.)

Finally, here is an example of the directive in action on Plunker: http://plnkr.co/edit/3YNLsyoG4PIBW6Kj7dRK?p=preview

Solution 5:

Based on answers in this thread I’ve created checklist-model directive that covers all cases:

  • simple array of primitives
  • array of objects (pick id or whole object)
  • object properties iteration

For topic-starter case it would be:

<label ng-repeat="fruit in ['apple', 'orange', 'pear', 'naartjie']">
    <input type="checkbox" checklist-model="selectedFruits" checklist-value="fruit"> {{fruit}}
</label>

Solution 6:

The checklist-model directive on GitHub by Vitaliy Potapov absolutely worked for me (using complex objects).

I spent a few hours trying to get the other solutions to work with no luck. Great job, vitalets!!