What is the best way to modify directives in response to updates in services?

Question

What is the best way to modify directives in response to updates in services?

In my directive (parent-directive), I have a slider called mySlider. When the slider is stopped, it triggers an event that calls an Angular $resource service with two parameters. The service then returns an object. The structure of the directives is as follows:

<parent-directive>
    <div ui-slider="slider.options" ng-model="mySlider" id="my-slider">
        <span child-directive-one></span>
        <span child-directive-two></span>
        <span child-directive-three></span>
        <div>
            <span child-directive-four></child-directive-four>
        </div>
    </parent-directive

When the user drags the slider, the service is called with different parameters to retrieve a new result. Based on this result, I need to update the child directives.

I am considering three ways to achieve this:

Using ng-model for all child elements instead of directives and binding them to the scope of a controller within the parent-directive.
The second option involves creating a controller within the parent-directive to send and receive data from the service and share it with the child-directives for updating purposes.
The last approach is to create a state variable in the service and update it using a controller similar to the first option mentioned above. Then, use $watch to monitor changes in the variable's state and update the child-directives accordingly.

What would be the best way to proceed?

You can take a look at a sample code here: http://jsfiddle.net/v5xL0dg9/2/

Thank you!

javascript angularjs angular-services angular-directive

Answer 1

Answer №1

ngModel is typically used for enabling two-way data binding, meaning it allows users to interact with the value of controls. However, since these components are intended to be display-only, using ngModel may not be the best choice in this scenario.
In usual cases, child directives rely on their parent directives to access methods from the parent controller. In your case, the parent controller needs to communicate with its children. One way to achieve this is by having each child call a `registerChild()` method, and then the parent can iterate through all registered children when necessary. While this approach works, it may seem cumbersome to implement.
It's important to note that services act as global singletons in AngularJS. Therefore, linking the service implementation to specific UI requirements may not be recommended.

Considering your current implementation resembles option 3, where the parent controller holds the data:

1) Store the data you want to share with child directives in a member variable of the parent controller:

myApp.directive('parentDirective', ['myService', function(myService){
    ...
    controller: function($scope) {
        ...
        this.sharedThing = ...;
    }
}]);

The `sharedThing` variable can be updated whenever the service returns new data or whenever necessary.

2) Have the child directives require the parent directive (similar to option 2), and set a watch on this property:

myApp.directive('childDirectiveOne', function() {
    return {
        ...
        require: 'parentDirective',
        link: function(scope, elem, attrs, parentDirective) {
            scope.$watch(
                function() {
                    return parentDirective.sharedThing;
                },
                function(newval) {
                    // perform actions based on the new value; likely requires updating the scope
                }
            });
        }
    };
});

Depending on the complexity of the data, a deep watch may be necessary.

Answer 2

ngModel is typically used for enabling two-way data binding, meaning it allows users to interact with the value of controls. However, since these components are intended to be display-only, using ngModel may not be the best choice in this scenario.
In usual cases, child directives rely on their parent directives to access methods from the parent controller. In your case, the parent controller needs to communicate with its children. One way to achieve this is by having each child call a `registerChild()` method, and then the parent can iterate through all registered children when necessary. While this approach works, it may seem cumbersome to implement.
It's important to note that services act as global singletons in AngularJS. Therefore, linking the service implementation to specific UI requirements may not be recommended.

Considering your current implementation resembles option 3, where the parent controller holds the data:

1) Store the data you want to share with child directives in a member variable of the parent controller:

myApp.directive('parentDirective', ['myService', function(myService){
    ...
    controller: function($scope) {
        ...
        this.sharedThing = ...;
    }
}]);

The `sharedThing` variable can be updated whenever the service returns new data or whenever necessary.

2) Have the child directives require the parent directive (similar to option 2), and set a watch on this property:

myApp.directive('childDirectiveOne', function() {
    return {
        ...
        require: 'parentDirective',
        link: function(scope, elem, attrs, parentDirective) {
            scope.$watch(
                function() {
                    return parentDirective.sharedThing;
                },
                function(newval) {
                    // perform actions based on the new value; likely requires updating the scope
                }
            });
        }
    };
});

Depending on the complexity of the data, a deep watch may be necessary.

What is the best way to modify directives in response to updates in services?

Answer №1

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