Google Choice: AngularJS

Sunday, February 12, 2017

AngularJS - Forms

AngularJS enriches form filling and validation. We can use ng-click to handle AngularJS click on button and use $dirty and $invalid flags to do the validations in seemless way. Use novalidate with a form declaration to disable any browser specific validation. Forms controls makes heavy use of Angular events. Let's have a quick look on events first.

Events

AngularJS provides multiple events which can be associated with the HTML controls. For example ng-click is normally associated with button. Following are supported events in Angular JS.

ng-click
ng-dbl-click
ng-mousedown
ng-mouseup
ng-mouseenter
ng-mouseleave
ng-mousemove
ng-mouseover
ng-keydown
ng-keyup
ng-keypress
ng-change

ng-click

Reset data of a form using on-click directive of a button.

<input name = "firstname" type = "text" ng-model = "firstName" required>
<input name = "lastname" type = "text" ng-model = "lastName" required>
<input name = "email" type = "email" ng-model = "email" required>
<button ng-click = "reset()">Reset</button>

<script>
   function studentController($scope) { 
      $scope.reset = function(){
         $scope.firstName = "Mahesh";
         $scope.lastName = "Parashar";
         $scope.email = "MaheshParashar@tutorialspoint.com";
      }   
      
      $scope.reset();
   }
</script>

Validate data

Following can be used to track error.

$dirty − states that value has been changed.
$invalid − states that value entered is invalid.
$error − states the exact error.

Example

Following example will showcase all the above mentioned directives.
testAngularJS.htm

<html>
   <head>
      <title>Angular JS Forms</title>
      <script src = "https://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.min.js"></script>
      
      <style>
         table, th , td {
            border: 1px solid grey;
            border-collapse: collapse;
            padding: 5px;
         }
         
         table tr:nth-child(odd) {
            background-color: #f2f2f2;
         }
         
         table tr:nth-child(even) {
            background-color: #ffffff;
         }
      </style>
      
   </head>
   <body>
      
      <h2>AngularJS Sample Application</h2>
      <div ng-app = "mainApp" ng-controller = "studentController">
         
         <form name = "studentForm" novalidate>
            <table border = "0">
               <tr>
                  <td>Enter first name:</td>
                  <td><input name = "firstname" type = "text" ng-model = "firstName" required>
                     <span style = "color:red" ng-show = "studentForm.firstname.$dirty && studentForm.firstname.$invalid">
                        <span ng-show = "studentForm.firstname.$error.required">First Name is required.</span>
                     </span>
                  </td>
               </tr>
               
               <tr>
                  <td>Enter last name: </td>
                  <td><input name = "lastname"  type = "text" ng-model = "lastName" required>
                     <span style = "color:red" ng-show = "studentForm.lastname.$dirty && studentForm.lastname.$invalid">
                        <span ng-show = "studentForm.lastname.$error.required">Last Name is required.</span>
                     </span>
                  </td>
               </tr>
               
               <tr>
                  <td>Email: </td><td><input name = "email" type = "email" ng-model = "email" length = "100" required>
                     <span style = "color:red" ng-show = "studentForm.email.$dirty && studentForm.email.$invalid">
                        <span ng-show = "studentForm.email.$error.required">Email is required.</span>
                        <span ng-show = "studentForm.email.$error.email">Invalid email address.</span>
                     </span>
                  </td>
               </tr>
               
               <tr>
                  <td>
                     <button ng-click = "reset()">Reset</button>
                  </td>
                  <td>
                     <button ng-disabled = "studentForm.firstname.$dirty &&
                        studentForm.firstname.$invalid || studentForm.lastname.$dirty &&
                        studentForm.lastname.$invalid || studentForm.email.$dirty &&
                        studentForm.email.$invalid" ng-click="submit()">Submit</button>
                  </td>
               </tr>
     
            </table>
         </form>
      </div>
      
      <script>
         var mainApp = angular.module("mainApp", []);
         
         mainApp.controller('studentController', function($scope) {
            $scope.reset = function(){
               $scope.firstName = "Mahesh";
               $scope.lastName = "Parashar";
               $scope.email = "MaheshParashar@tutorialspoint.com";
            }
            
            $scope.reset();
         });
      </script>
      
   </body>
</html>

Output

Open textAngularJS.htm in a web browser. See the result.

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