Utilizing ngModel within the controller of a custom directive in Angular, instead of the link function

Question

Utilizing ngModel within the controller of a custom directive in Angular, instead of the link function

Is there a way to require and use ngModel inside the controller of a custom Angular directive without using the link function? I have seen examples that use the link function, but I want to know if it's possible to access ngModel inside the directive controller. The method I tried below returns undefined. Is there another approach to achieve this? I need to validate the component and apply the invalid class to the error object.

//directive
angular.module('myApp', [])
  .directive('validator', function (){
    return {
      restrict: 'E',
      require: {
           ngModelCtrl: 'ngModel',
           formCtrl: '?^form'
      },
      replace: true,
      templateUrl: 'view.html',
      scope: {},
      controllerAs: 'ctrl',
      bindToController: {
         rows: '=',
         onSelected: '&?' //passsed selected row outside component
         typedText: '&?' //text typed into input passed outside so developer can create a custom filter, overriding the auto
         textFiltered: '@?' //text return from the custom filter
         ngRequired: "=?" //default false, when set to true the component needs to validate that something was selected on blur. The selection is not put into the input element all the time so it can't validate based on whether or not something is in the input element itself. I need to validate inside the controller where I can see if 'this.ngModel' (selectedRow - not passed through scope) is undefined or not.
      },
      controller: ["$scope", "$element", function ($scope, $element){
         var ctrl = this;
         ctrl.rowWasSelected;

         //called when a user clicks the dropdown to select an item
          ctrl.rowSelected = function (row){
               ctrl.rowWasSelected = true;
               ctrl.searchText = row.name; //place the name property of the dropdown data into ng-model in the input element
          }

         ctrl.$onInit = $onInit;
         function $onInit (){
             ctrl.ngModelCtrl.$validators.invalidInput = validate;            
          }

        function validate (modelValue, viewValue) {
             var inputField = ctrl.formCtrl.name;
             var ddField = ctrl.formCtrl.listData;

             inputField.$setValidity('invalidInput', ddField.$touched && ctrl.rowWasSelected);

            return true;
          }          
       }];
   }
});

//template
<form name="validatorForm" novalidate>
  <div class="form-group" ng-class="{ng-invalid:validatorForm.name.$error.invalid}">
     <label for="name">Names</label>
     <input type="name" class="form-control" name="name" placeholder="Your name" ng-change="typedText(text)" ng-model="ctrl.textFiltered" ng-blur="ctrl.validate()" ng-required="ctrl.ngRequired">
  </div>
  <ul ng-show="show list as toggled on and off" name="listData" required>
    <li ng-repeat="row in ctrl.rows" ng-click="ctrl.rowSelected({selected: row}) filterBy:'ctrl.textFiltered' ng-class="{'active':row === ctrl.ngModel}">{{row}}<li>
  </ul>
</form>

//html
<validator
   rows="[{name:'tim', city:'town', state:'state', zip: 34343}]"
   on-selected="ctrl.doSomethingWithSelectedRow(selected)"
   typed-text="ctrl.manualFilter(text)"
   text-filtered="ctrl.textReturnedFromManualFilter"
   ng-required="true">
</validator>

javascript angularjs angularjs-directive angular-ngmodel angularjs-validation

Answer 1

Answer №1

After updating the code a bit, I realized that you might need to be using the latest version of Angular for some of these changes. Upon reviewing your question, it's unclear what specific issue you're facing, whether it's related to using 'required' in the directive definition object or utilizing the 'ngRequired' attribute. The code below eliminates the need for $scope:

angular.module('myApp', []);
angular.module('myApp').directive('validator', validator);

function validator (){
    return {
        restrict: 'E',
        require: {
            ngModelCtrl: 'ngModel'
        },
        replace: true,
        templateUrl: 'view.html',
        scope: {}, //this controls the kind of scope. Only use {} if you want an isolated scope.
        controllerAs: 'ctrl',
        bindToController: {
            rows: '=',
            onSelected: '&?', //pass selected row outside component
            typedText: '&?', //text typed into input passed outside for custom filter
            textFiltered: '@?', //text return from custom filter
            ngRequired: "=?" //default false, set to true for validation on blur
        },
        controller: 'validatorController'
    }
}

//usually do this in a new file

angular.module('myApp').controller('validatorController', validatorController);
validatorController.$inject = ['$element'];

function validatorController($element){
    var ctrl = this;

    //controller methods
    ctrl.validate = validate;

    ctrl.$onInit = $onInit; //angular will push this after all controllers have been initialized

    function $onInit() {
        if(ctrl.ngRequired)
            ctrl.ngModelCtrl.$validators.myCustomRequiredValidator = validate;
    }

    function validate (modelValue, viewValue){
        return rowWasSelected !== undefined
    }
}

Here are some insights from Angular's docs on $compile:

If the require property is an object and bindToController is truthy, then the required controllers are bound to the controller using the keys of the require property. This binding occurs after all the controllers have been constructed but before $onInit is called.

and

Deprecation warning: although bindings for non-ES6 class controllers are currently bound to this before the controller constructor is called, this use is now deprecated. Initialization code relying on bindings should be placed inside a $onInit method on the controller.

Ensure you are using the latest Angular version for these features to work correctly. Previously, I encountered issues with compatibility on versions below 1.4.7.

Second Edit: Clarifying a few points:

1) The .ng-invalid class is applied to any invalid input in an Angular validated form. To add a red border after blur, use a CSS rule like this:

.ng-invalid.ng-touched {
   border: 1px #f00 solid;
}

2) $formatters format model values to view values and $parsers validate input values before updating model values.

3) Logic involving values bound to the controller via bindToController should be placed in $onInit. This includes ngModelCtrl.

4) To trigger validation only after blur, utilize ng-model-options or test for $touched in the validator function.

To access formCtrl, add formCtrl: '^form' to your require object.

Answer 2

After updating the code a bit, I realized that you might need to be using the latest version of Angular for some of these changes. Upon reviewing your question, it's unclear what specific issue you're facing, whether it's related to using 'required' in the directive definition object or utilizing the 'ngRequired' attribute. The code below eliminates the need for $scope:

angular.module('myApp', []);
angular.module('myApp').directive('validator', validator);

function validator (){
    return {
        restrict: 'E',
        require: {
            ngModelCtrl: 'ngModel'
        },
        replace: true,
        templateUrl: 'view.html',
        scope: {}, //this controls the kind of scope. Only use {} if you want an isolated scope.
        controllerAs: 'ctrl',
        bindToController: {
            rows: '=',
            onSelected: '&?', //pass selected row outside component
            typedText: '&?', //text typed into input passed outside for custom filter
            textFiltered: '@?', //text return from custom filter
            ngRequired: "=?" //default false, set to true for validation on blur
        },
        controller: 'validatorController'
    }
}

//usually do this in a new file

angular.module('myApp').controller('validatorController', validatorController);
validatorController.$inject = ['$element'];

function validatorController($element){
    var ctrl = this;

    //controller methods
    ctrl.validate = validate;

    ctrl.$onInit = $onInit; //angular will push this after all controllers have been initialized

    function $onInit() {
        if(ctrl.ngRequired)
            ctrl.ngModelCtrl.$validators.myCustomRequiredValidator = validate;
    }

    function validate (modelValue, viewValue){
        return rowWasSelected !== undefined
    }
}

Here are some insights from Angular's docs on $compile:

If the require property is an object and bindToController is truthy, then the required controllers are bound to the controller using the keys of the require property. This binding occurs after all the controllers have been constructed but before $onInit is called.

and

Deprecation warning: although bindings for non-ES6 class controllers are currently bound to this before the controller constructor is called, this use is now deprecated. Initialization code relying on bindings should be placed inside a $onInit method on the controller.

Ensure you are using the latest Angular version for these features to work correctly. Previously, I encountered issues with compatibility on versions below 1.4.7.

Second Edit: Clarifying a few points:

1) The .ng-invalid class is applied to any invalid input in an Angular validated form. To add a red border after blur, use a CSS rule like this:

.ng-invalid.ng-touched {
   border: 1px #f00 solid;
}

2) $formatters format model values to view values and $parsers validate input values before updating model values.

3) Logic involving values bound to the controller via bindToController should be placed in $onInit. This includes ngModelCtrl.

4) To trigger validation only after blur, utilize ng-model-options or test for $touched in the validator function.

To access formCtrl, add formCtrl: '^form' to your require object.

Answer 3

Answer №2

To access the information provided by ngModel in a custom directive, the simplest method is to set the scope to false. While this should be the default behavior, explicitly setting it can be beneficial when working with multiple directives. By doing so, the directive will inherit the controller and controller alias as if it were a natural part of the view.

Here is an example of the directive:

.directive('myValidator', function (){
return {
  restrict: 'E',
  replace: true,
  templateUrl: 'view.html',
  scope: false
  };
}

You do not need to make significant changes to the template. Just ensure that the ng-model="ctrl.name" is binding to something on your main controller or the relevant controller for the rest of the view. You can also move the validation function to the main controller or a service and inject it into the controller.

Utilizing compile or link in a custom directive can enhance its versatility. These options allow you to pass values for directives, attributes, or HTML tags. While ngModel is accessible, you may not always use ctrl.user with every instance of the custom directive. Using compile or link enables you to set the value of ngModel each time the directive is used.

Answer 4

To access the information provided by ngModel in a custom directive, the simplest method is to set the scope to false. While this should be the default behavior, explicitly setting it can be beneficial when working with multiple directives. By doing so, the directive will inherit the controller and controller alias as if it were a natural part of the view.

Here is an example of the directive:

.directive('myValidator', function (){
return {
  restrict: 'E',
  replace: true,
  templateUrl: 'view.html',
  scope: false
  };
}

You do not need to make significant changes to the template. Just ensure that the ng-model="ctrl.name" is binding to something on your main controller or the relevant controller for the rest of the view. You can also move the validation function to the main controller or a service and inject it into the controller.

Utilizing compile or link in a custom directive can enhance its versatility. These options allow you to pass values for directives, attributes, or HTML tags. While ngModel is accessible, you may not always use ctrl.user with every instance of the custom directive. Using compile or link enables you to set the value of ngModel each time the directive is used.

Utilizing ngModel within the controller of a custom directive in Angular, instead of the link function

Answer №1

Answer №2

Similar questions

Tips on creating a responsive absolute div

What is the fewest amount of commands needed to generate a client-side Javascript code that is ready for use?

Unlocking the power of bitwise operations in VueJS with Javascript

When the app loads in AngularJS, make sure to call the jQuery plugin. Additionally, remember to call

The VueJS function is not defined

Dealing with Errors using Restangular

Turn off the ability to click on images, but allow users to access the right

How to set the default value for an angularJS select dropdown

Is there a way to iterate through two arrays simultaneously in React components?

Challenges with the "//" syntax in UNIX

Using asynchronous functions in React Native still generates a promise despite the presence of the 'await' keyword

Lack of Ajax query string parameters

ng-pattern for requiring whole numbers only with no decimal points

What is the best method for clearing all session cookies in my React application?

Chrome's keyup event restricts the use of arrow keys in text fields

Incorporate create-react-app with Express

history.js - failure to save the first page in browsing history

It appears that Promise.all is not adequately ensuring that all tasks are completed before moving on

After logging in, I am unable to redirect to another PHP page as the login form simply reloads on the same page

Retrieve identification details from a button within an ion-item located in an ion-list