Stéphane Stéphane - 1 month ago 15
AngularJS Question

AngularJS checkbox filter

I would like to filter the results.

There is a list of wines, my wish is when no checkbox is checked, the entire list of wine is displayed.


  • when only 1 checkbox is checked is displayed the related category

  • when more than one checkbox are checked the related categories are displayed



I'm a newbie to AngularJS, I tried with ng-model wihout success, here is the code without ng-model associated to the function:

<html ng-app="exampleApp">
<head>
<title></title>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.0-beta.10/angular.min.js"></script>

<script>
angular.module("exampleApp", [])
.controller("defaultCtrl", function ($scope) {
$scope.wines = [
{ name: "Wine A", category: "red" },
{ name: "Wine B", category: "red" },
{ name: "wine C", category: "white" },
{ name: "Wine D", category: "red" },
{ name: "Wine E", category: "red" },
{ name: "wine F", category: "white" },
{ name: "wine G", category: "champagne"},
{ name: "wine H", category: "champagne" }

];


$scope.selectItems = function (item) {
return item.category == "red";
};

$scope.selectItems = function (item) {
return item.category == "white";
};

$scope.selectItems = function (item) {
return item.category == "champagne";
};
});
</script>
</head>
<body ng-controller="defaultCtrl">

<h4>red: <input type="checkbox"></h4>
<h4>white: <input type="checkbox"></h4>
<h4>champagne: <input type="checkbox"></h4>



<div ng-repeat="w in wines | filter:selectItems">
{{w.name}}
{{w.category}}
</div>


</body>
</html>


How to use ng-model or ng-change to associate a function to each checkbox button to have a real time filtering model??

Answer

There are several implementations possible. Here's one:

  1. Have a $scope.filter = {} object to hold the state of each filter. E.g. {red: true, white: false...}.

  2. Associate each checkbox with the corresponding property using ng-model. E.g.: input type="checkbox" ng-model="filter['red']" />.

  3. Have a function (e.g. $scope.filterByCategory(wine)) that decides if a wine should be displayed or not (based on the $scope.filter object).

  4. Use that function to filter the items based on their category. E.g. <div ng-repeat="wine in wines | filter:filterByCategory">


The filterByCategory function could be implemented like this:

function filterByCategory(wine) {
  // Display the wine if
  var displayWine =
      // the wine's category checkbox is checked (`filter[category]` is true)
      $scope.filter[wine.category] ||   // or 

      // no checkbox is checked (all `filter[...]` are false)
      noFilter($scope.filter);

  return displayWine;
};

where noFilter() is a function that checks if there is any filter activated (and returns true if there is none):

function noFilter(filterObj) {
  return Object.
    keys(filterObj).
    every(function (key) { return !filterObj[key]; });
}

See, also, this short demo.


UPDATE:

I created a modified version, which supports multiple filters (not just filtering by category).
Basically, it dynamically detects the available properties (based on the first wine element), adds controls (groups of check-boxes) for applying filters based on each property and features a custom filter function that:

  1. Filters each wine item, based on every property.
  2. If a property has no filter applied (i.e. no check-box checked), it is ignored.
  3. If a property has check-boxes checked, it is used for filtering out wine items (see above).
  4. There is code for applying multiple filters using AND (i.e. all properties must match) or OR (at least one property must match).

See, also, this updated demo.