Validating an Element Directive in AngularJS: A Step-by-Step Guide

Question

Validating an Element Directive in AngularJS: A Step-by-Step Guide

I have developed a directive for handling numbers

function numberInputDirective()
 {
    return 
    {
        restrict: 'E',
        scope: 
        {
            model: '=',
            disabled: '=?',
            decimals: '=?',
            form: '=',
            name: '='
        },
        require: '^form',
        replace: true,
        templateUrl: 'directives/pxNumberInput.html',
        link: function (scope, element, attrs, form) 
        {
              scope.inError = function () 
              {
                  return form.control.$valid; //I need to do something like this    
              }
        }
    }

In the isError function, I need to verify if the value in the control is valid or not

The template looks like this:

<input class="input-field form-control" type="number" ng-model="model">

Here is how you would implement it in HTML:

 <form role="form" class="form-horizontal psi-keyrates-yieldform psi-keyrates-historical-topcurves" name="SampleControlsForm" novalidate>
      <px-number-input id="objectiveid" name="numericExample"    model="sampleDataModel.numericField" placeholder="Enter numeric value" label="Numeric" required maxlength="10"></px-number-input>
</form>

While checking if the form is valid can be done through the form variable, we also need to know if this specific directive has a valid value when the form is submitted. Something similar to form.control.$valid.

Since I don't know the name of the control in this directive beforehand, I attempted: var elem = ctrl.$name + '.' + element.attr('name') + '.$valid'; This expression returns "SampleControlsForm.numericExample.$valid", but adding a watch on it does not provide any assistance and neither does scope.$eval.

I am certain that I am not utilizing it correctly.

javascript angularjs forms validation

Answer 1

Answer №1

Below is an illustration of a unique number validation feature that demonstrates:

Guidelines on requiring ngModel to access its controller.
Steps to add a custom validator by appending a property to the $validators object (applicable for angular version 1.3 and above). For versions lower than 1.3, utilize ngModelController.$setValidity
Tutorial on setting up a $watch function on the $error object to dynamically insert/remove an image based on the validation result.
The process of creating a distinct directive compatible with ngModel without defining a specific template.

The $validators object enables the registration of multiple validation directives for the same ngModel. To include a new validator, simply incorporate the validation directive within the same element as ngModel.


var app = angular.module('app', []);
app.directive('myNumber', function() {
  return {
    restrict: 'A',
    require: 'ngModel',
    compile: function(element, attr) {
      var img = angular.element('<img src="https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTTyptDmp09eMq1nHtcJHVTAMkKgqdi1ZiGMQSjFeYNApkO92zhCA" />');
           
      return function(scope, element, attr, ngModelCtrl) {
        function isNumber(n) {
            return !isNaN(parseFloat(n)) && isFinite(n);
        }
        
        ngModelCtrl.$validators.mynumber = function(val) {
          return isNumber(val);
        };
        scope.$watch(function() {
          return ngModelCtrl.$error.mynumber;
        }, 
        function(newVal) {
          if (newVal) {
            element.after(img);
          }
          else {
            img.remove();
          }
        });
      }
    }
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.9/angular.min.js"></script>
<div ng-app="app">
  <form name="form">
    <input type="text" name="age" my-number ng-model="age" /> {{ age }}
  </form>
  {{ form.age.$error }}
</div>

Answer 2

Below is an illustration of a unique number validation feature that demonstrates:

Guidelines on requiring ngModel to access its controller.
Steps to add a custom validator by appending a property to the $validators object (applicable for angular version 1.3 and above). For versions lower than 1.3, utilize ngModelController.$setValidity
Tutorial on setting up a $watch function on the $error object to dynamically insert/remove an image based on the validation result.
The process of creating a distinct directive compatible with ngModel without defining a specific template.

The $validators object enables the registration of multiple validation directives for the same ngModel. To include a new validator, simply incorporate the validation directive within the same element as ngModel.


var app = angular.module('app', []);
app.directive('myNumber', function() {
  return {
    restrict: 'A',
    require: 'ngModel',
    compile: function(element, attr) {
      var img = angular.element('<img src="https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTTyptDmp09eMq1nHtcJHVTAMkKgqdi1ZiGMQSjFeYNApkO92zhCA" />');
           
      return function(scope, element, attr, ngModelCtrl) {
        function isNumber(n) {
            return !isNaN(parseFloat(n)) && isFinite(n);
        }
        
        ngModelCtrl.$validators.mynumber = function(val) {
          return isNumber(val);
        };
        scope.$watch(function() {
          return ngModelCtrl.$error.mynumber;
        }, 
        function(newVal) {
          if (newVal) {
            element.after(img);
          }
          else {
            img.remove();
          }
        });
      }
    }
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.9/angular.min.js"></script>
<div ng-app="app">
  <form name="form">
    <input type="text" name="age" my-number ng-model="age" /> {{ age }}
  </form>
  {{ form.age.$error }}
</div>

Validating an Element Directive in AngularJS: A Step-by-Step Guide

Answer №1

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