angular Way of: show or hide element after button click

Question

I am pretty new to angular and i cant get it right.

inside the following example i am trying to show the answer to a question after the user clicks on the corresponding button. before the answer is shown i want to run a function that checks if the user has the privilege to reveal the answer. in the example i assume he has the rights.

what i have to do to to remove the "ng-hide" class in the row where the button was clicked.

i appreciate any kind of help. thanks in advance

var myApp = angular.module('myApp', []);
myApp.controller('QuestionCtlr', ['$scope', '$log', function($scope, $log) {
    $scope.questions = [
        ["what is 1+1?"],
        ["what color of the sky"],
        ["what is the answer to the universe"]
    ];
    $scope.answers = [
        2, ["blue, black or orange"],
        40
    ];

    $scope.hideme = function(i) {
        $log.log("element " + i + " was cicked");
        
        //this will be detemined within a fct, so lets asume the has the according rights
        var userPrivilege = true;

        if (userPrivilege) {
            //HOW TO: show the answer with the index i
        }
    }
}]);

<!DOCTYPE html>
<html lang="en" ng-app="myApp">

<head>
    <meta charset="UTF-8">
    <!-- angular -->
    <script src="https://code.angularjs.org/1.4.0/angular.min.js"></script>
    <script src="app.js"></script>
    <!-- jquery -->
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
    <!-- bootstrap -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" />
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
</head>

<body ng-controller=QuestionCtlr>
    <table class="table table-hover">
        <thead>
            <tr>
                <th>Question</th>
                <th>Answer</th>
            </tr>
        </thead>
        <tbody>
            <tr ng-repeat="q in questions track by $index">
                <td>{{q[0]}}</td>
                <td class = "ng-hide">{{q[0]}}</td>
                <td>
                    <button type="button" ng-click="hideme($index)" class="btn btn-default">show me</button>
                </td>
            </tr>
        </tbody>
    </table>
</body>

</html>

I would use a bit more than just simple arrays of Strings... I would create a array of objects containing all the flags you need and programe a bit more object-oriented. Like this: plunker — skubski
– skubski, Commented Jul 9, 2015 at 13:49
hi, thanks for you answer. Yes you are completely right, i wanted to keep it simple for the question to focus on the angular part. In the end all the date will be in a mySQL database — user2344231
– user2344231, Commented Jul 9, 2015 at 17:11

Mike Chamberlain · Accepted Answer · 2015-07-09 14:16:46Z

Here's a complete working example.

Things I changed:

The answers are now stored as a property of each question. This makes the code neater (no need to track by $index).
The ng-show directive is used as an attribute instead of a class, and is bound to a showAnswers property of the question.
The showme function sets the showAnswers property to true when you click the button.

var myApp = angular.module('myApp', []);
myApp.controller('QuestionCtlr', ['$scope', '$log', function($scope, $log) {
    $scope.questions = [
        {question: "what is 1+1?", answers: [2]},
        {question: "what color of the sky", answers: ["blue", "black", "orange"]},
        {question: "what is the answer to the universe", answers: [42]}
    ];

    $scope.showme = function(q) {
        $log.log("question " + q.question + " was cicked");
        
       var userPrivilege = true;

        if (userPrivilege) {
            q.showAnswers = true;
        }
    }
}]);

<!DOCTYPE html>
<html lang="en" ng-app="myApp">

<head>
    <meta charset="UTF-8">
    <!-- angular -->
    <script src="https://code.angularjs.org/1.4.0/angular.min.js"></script>
    <script src="app.js"></script>
    <!-- jquery -->
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
    <!-- bootstrap -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css" />
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
</head>

<body ng-controller=QuestionCtlr>
    <table class="table table-hover">
        <thead>
            <tr>
                <th>Question</th>
                <th colspan="2">Answer</th>
            </tr>
        </thead>
        <tbody>
            <tr ng-repeat="q in questions">
                <td >{{q.question}}</td>
                <td ng-show="q.showAnswers">
                     <div ng-repeat="a in q.answers">{{a}}</div>
                </td>
                <td>
                    <button type="button" ng-click="showme(q)" class="btn btn-default">show me</button>
                </td>
            </tr>
        </tbody>
    </table>
</body>

</html>

Sudharsan S · Accepted Answer · 2015-07-09 13:43:51Z

Try in html

<table class="table table-hover">
        <thead>
            <tr>
                <th>Question</th>
                <th>Answer</th>
            </tr>
        </thead>
        <tbody>
            <tr ng-repeat="q in questions">
                <td>{{q[0]}}</td>
                <td ng-class="{hide : active != $index}">{{answers[$index]}}</td>
                <td>
                    <button type="button" ng-click="hideme($index)" class="btn btn-default">show me</button>
                </td>
            </tr>
        </tbody>
    </table>

angular

var myApp = angular.module('myApp', []);
myApp.controller('QuestionCtlr', ['$scope', '$log', function($scope, $log) {
    $scope.questions = [
        ["what is 1+1?"],
        ["what color of the sky"],
        ["what is the answer to the universe"]
    ];
    $scope.answers = [
        2, ["blue, black or orange"],
        40
    ];
    $scope.active = null;
    $scope.hideme = function(i) {
        $scope.active = i; 
    }
}]);

Fiddle

Guinn · Accepted Answer · 2015-07-09 13:40:33Z

0

Taking your 'privilege' request in consideration, I think you will want to create a condition. Instead of adding the class ng-hide, use ng-hide, ng-show or ng-if like this:

<td ng-show="hasPrivilege && show[$index]">
    <!--or ng-hide or ng-if-->

and your button:

<button type="button" ng-click="hideme($index)">

This will show the td if both statements are true. If one or both of them are false, it won't show the element.

then in your controller:

$scope.hideme = function(index) {
    $scope.hasPrivilege = getPrivilege();
    $scope.show[index] = true;
}

the getPrivilege() function should return true or false based on whether the user has the privilege.

answered Jul 9, 2015 at 13:40

Guinn

1,39514 silver badges29 bronze badges

Comments

stackg91 · Accepted Answer · 2015-07-09 13:51:28Z

0

Okay first of all you can use

ng-if="condition"   //gets only rendered if condition is true
ng-show="condition" //shows when condition is true 
ng-hide="condition" //hides when condition is true

So on your button

ng-click="showAnswer()"

In your Controller

$scope.displayAnswer = false;
$scope.showAnswer = function(){
  if(hasRights == true){
      $scope.displayAnswer = true //this is used for the hide and show
   }
}

In your html 3 possible ways

<span ng-if="displayAnswer == true">This is the answer!!!</span>

<span ng-show="displayAnswer == true">This is the answer!!!</span>

<span ng-hide="displayAnswer == false">This is the answer!!!</span>

<button ng-click="showAnswer()">This is the answer!!!</span>

2nd Solution with toggle

if you want to hide the Answer again on the same button This shows and hides the button depending if its currently shown or hidden

$scope.toggleAnswer = function(displayAnswer){
  if(hasRights == true && $scope.displayAnswer == false){
      $scope.displayAnswer = true //this is used for the hide and show
   }else if($scope.displayAnswer == true){
      $scope.displayAnswer = false;
   }
}

2nd Html

<span ng-if="displayAnswer == true">This is the answer!!!</span>
<button ng-click="toggleAnswer(displayAnswer)">This is the answer!!!</span>

In your case

<button ng-click="toggleAnswer($index)">Hide / Show</button>

And In your Controller

  $scope.answers = [{A: 2, show: false},{A: 'blue', show: false}]
 $scope.toggleAnswer = function(index){
  if(hasRights == true){
      $scope.answers[index].show = true //this is used for the hide and show
   }
}

in HTML

<span ng-if="item.show == true">The Answer !!</span>
//the item is coming from item in Answers from the ng-repeat

edited Jul 9, 2015 at 13:51

answered Jul 9, 2015 at 13:39

stackg91

5948 silver badges25 bronze badges

8 Comments

David Barker Over a year ago

Yep but this won't work in the ng-repeat. All answers will be shown.

stackg91 Over a year ago

you can simply pass the Index of the Question <button ng-click="showAnswer($index)">This is the answer!!!</span> and then return $scope.answers[passedIndex]

David Barker Over a year ago

Add it to your answer then ;-)

stackg91 Over a year ago

added it to my answer

skubski Over a year ago

As soon as the question array gets sorted or filtered, your solution breaks. It would have been much better to introduce a question object containing: the question, answer and a display property. Even adding a question requires you to change the code in two places.

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