Utilizing Directives to Gain Scope Access in a Separate Module

Recently delving into AngularJS, I find myself grappling with the best approach to a particular issue, especially in my utilization of directives.

In my main app, I aim to consolidate some common code, such as a directive for displaying messages on an HTML page. A controller is responsible for making a REST API call to authenticate credentials and assigns data to $scope. The goal is for the directive to utilize this scoped data for message display and formatting. My research suggests that handling this directly in the controller may not be ideal practice. I understand that I could opt for direct implementation in the controller and include a div in the HTML like so:

<div>{{validation.message}}</div>

The simplified HTML structure is as follows:

    <html data-ng-app="myApp" data-ng-strict-di>
        <body>
            <div data-ng-view data-ng-controller="MainController">
                <div data-ng-app="StoredAccountsModule" data-ng-controller="AccountController">
                    <button class="btn btn-default" data-ng-click="modalOptions.verify(newAccount)">Verify Credentials</button>
                    <div data-myappmessage></div>
                </div>
            </div>
        </body>
    </html>

The directive is defined as:

angular.module("myApp").directive("myappmessage", function () {
    //&#9989 : &#10006
    return {
        link: function postLink(scope, element, attrs) {

            element.html('<span>' + scope.validation.message + '</span>');
    }
    };
});

I'm aware that there might be missing connections between controllers, modules, and directives.

UPDATE

With valuable feedback from everyone, progress has been made in ironing out the complexities of my objective. Presently, I am focusing on initiating account validation through a Bootstrap modal triggered by a button click, which triggers an API call to fetch validation information. The modal is instantiated as a service following a guide found here: . Key snippets related to the modal window are:

<div data-ng-controller="MainController">
    <div data-simplevalidation></div>
</div>
<div class="modal-footer">
    <button class="btn btn-primary" data-ng-click="modalOptions.ok(newAccount)">{{modalOptions.actionButtonText}}</button>
    <button class="btn btn-warning" data-ng-click="modalOptions.close('cancel')">{{modalOptions.closeButtonText}}</button>
    <button data-ng-controller="MainController" class="btn btn-default" data-ng-click="verifyAccount(newAccount)">Verify Credentials</button>
</div>

And the modal launched from:

<div data-ng-controller="StoredAccountsIndexController" style="width:auto;text-align:center;">
    <table style="border:1px solid black;margin:auto;">
        <tfoot>
            <tr>
                <td colspan="2"><button type="button" class="btn btn-primary" data-ng-click="open()">Add New Stored Account</button></td>
            </tr>
        </tfoot>
    </table>
</div>

The revised directive now looks like this:

angular.module("myApp").directive("simplevalidation", function () {
    return {
        template: '<button type="button" class="btn btn-default" data-ng-click=verifyAccount(newAccount)>Verify</button><span></span>',
        link: function ($scope, element, attrs) {
            $scope.$watchGroup(["validation.message", "validation.success"], function () {

                if ($scope.validation.success != null) {
                    if ($scope.validation.success) {
                        element.children("span").html($scope.validation.message + " " + $scope.validation.symbol);
                        element.children("span").css("color", "green")
                    }
                    else {
                        element.children("span").html($scope.validation.message + " " + $scope.validation.symbol);
                        element.children("span").css("color", "red")
                    }
                }

            }, true);
        }
    };
});

Only one application 'myApp' is declared on the page. The challenge seems to lie within the modal's scope. When utilizing the button provided by the directive template, everything functions correctly. However, using the button in the modal footer results in a fired API call but no visible update on the scope. The respective controller managing this call is:

angular.module("myApp").controller("MainController", ['$scope', '$timeout', "StoredAccountsFactory", function ($scope, $timeout, StoredAccountsFactory) {
    $scope.validation = {}

    $scope.verifyAccount = function (account) {
        $scope.validation = {};

        StoredAccountsFactory.validateStoredAccount(account).success(function (data, status, headers, config) {
            $scope.validation.message = "Account credentials verified";
            $scope.validation.success = true;
            $scope.validation.symbol = "&#9989;"
        }).error(function (data, status, headers, config) {
            $scope.validation.message = data;
            $scope.validation.success = false;
            $scope.validation.symbol = "&#10006;"
        });
    }
}]);

Alternative attempts have included a directive format presumed to align better with directive scope management, yet no change in outcome has been observed.

angular.module("myApp").directive("simplevalidation", function () {
    //add these attributes to the directive element
    //data-validate="verifyAccount(newAccount)" data-validationmessage="validation.message" data-validationsuccess="validation.success"

    return {
        scope: {
            validate: '&',
            validationmessage: '=',
            validationsuccess: '='
        },
        template: '<button type="button" data-ng-click=validate()>Verify</button><span></span>',
        link: function ($scope, element, attrs) {
            $scope.$watchGroup(["validationmessage", "validationsuccess"], function () {

                if ($scope.validationsuccess != null) {
                    if ($scope.validationsuccess) {
                        element.children("span").html($scope.validationmessage + " " + " &#9989;");
                        element.children("span").css("color", "green");
                    }
                    else {
                        element.children("span").html($scope.validationmessage + " " + " &#10006;");
                        element.children("span").css("color", "red");
                    }
                }

            }, true);
    }

    };
});

Answer №1

Your understanding of certain concepts here seems to be a bit off, which might be complicating your approach.

1. Modules: Modules are simply a way to organize code based on dependencies. Once loaded, it doesn't matter much which module hosts which service/controller/directive.

2. App and ng-app: Ideally, there should be only one app per page. While you can have multiple apps, doing so requires manual use of angular.bootstrap, and nesting is not supported. Apps do not share instances of services or scopes, making each app an isolated execution unit in Angular's perspective.

Therefore, the nesting of StoredAccountsModule within myApp is incorrect:

<html ng-app="myApp" >
  <body>
     <div data-ng-view data-ng-controller="MainController">
        <div data-ng-app="StoredAccountsModule">
           ...
        </div>
     </div>
  </body>
</html>

3. Controllers:

Controllers define and set the View Model (via $scope or with Controller As approach). Your statement:

"I know I could do this directly in the controller and just put a div in the html like:"

<div>{{validation.message}}</div>

implying that creating a directive instead of manipulating the view directly in the controller is against best practices is inaccurate.

What is discouraged is manipulating or accessing the View (DOM) in the controller. The controller focuses on translating data between backend Models and ViewModels, handling app logic and architecture without direct interaction with the View.

This separation and Dependency Injection (DI) make controllers easily testable.

4. Directives: Directives primarily provide reusable functionality that interacts with the DOM. Ideally, they should not assume anything about surrounding HTML or controllers.

Angular allows directives to use the outer scope but reduces reusability. Thus, your directive myappmessage may not add significant value.

When creating a directive, consider MVVM principles supported by Angular, giving them their own scope and controller while utilizing other built-in directives for functionality.

5. Scope: Scope exists independently of Modules, Controllers, or Directives. Therefore, the question "accessing scope from another module" is irrelevant. Angular creates a root scope for an App.

Controllers and Directives share scope unless a directive isolates its scope, allowing parent controllers to publish variables for subordinates through scope inheritance.

While scope inheritance can facilitate communication between controllers, some view it as a questionable practice due to prototypical inheritance constraints.

app.controller("ParentCtrl", function($scope){
   var VM = $scope.VM = ($scope.VM || {});

   VM.isBusy = false;
})
.controller("ChildCtrl", function($scope, $http){
   var VM = $scope.VM = ($scope.VM || {});

   $scope.loadSomething = function(){
      VM.isBusy = true;
      $http.get("something").then(function(d){
         VM.isBusy = false;
      });
   }
});

In the View:

<div ng-controller="ParentCtrl">
  <div ng-show="VM.isBusy">loading...</div>
  <div ng-controller="ChildCtrl">
    <button ng-click="loadSomething()">load</button>
  </div>
</div>

(Note: These controllers could also come from different modules)

Answer №2

It is recommended that you create a self-contained directive instead of directly accessing the parent scope and adding a watcher to react to changes.

    angular.module("myApp").directive("customMessage", function () {
        //&#9989 : &#10006
        return {
            scope: { 
              message: '='
            },
            link: function postLink(scope, element, attrs) {                            
                scope.$watch('message', function(value) {
                    element.html('<span>' + value + '</span>');
                });
            }
        };
   });

You can then use it in this way:

<div data-custom-message message="validation.messages"></div>

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