Utilizing Angular Directives and Controllers for Improved Efficiency

Question

Utilizing Angular Directives and Controllers for Improved Efficiency

I have developed a custom dropdown option selector which is functioning well. It includes functions to fetch data from a specified URL in order to populate a list.

However, the issue arises when I attempt to reuse this component in a different section of my application with a separate dataset. This results in duplication of data and multiple executions of the controller's functions.

My understanding is that there are two main problems at hand. Firstly, services act as singletons, meaning that when the function to populate data is executed, it simply appends the new data to the existing dataset due to the presence of only one instance of the service.

Secondly, controllers do possess instances, leading to the execution of functions in each instance, thereby causing repetition.

The simplest solution might be to duplicate the component and assign it a different name. While this may resolve the issue temporarily, it would result in creating multiple copies of the same component if reusability for multiple instances is desired, which is not ideal.

Coming from an object-oriented programming background in Java, I understand that I might be applying OOP techniques in a language that does not fully support them ;)

Therefore, I realize the necessity to rethink my approach, but I seem to have hit a barrier. What would be the best way to tackle this problem?

Below is a JSFiddle link to provide better insight into what I am encountering:


var app = angular.module('myApp',[]);

app.directive('mySelector', function () {
return {
 scope: {
      mydata: '='
    },
    restrict: 'EA',
    template:'<select ng-model="timePeriodSelection" ng-options="timePeriodOption.name for timePeriodOption in timePeriodOptions"><option value="">Choose time period</option></select>',
controller: function($scope, myService) {
    //$scope.name = 'Superhero';
    console.log('test',$scope.mydata);
    myService.setData($scope.mydata);
    $scope.timePeriodOptions = myService.getData();
  console.log('test2',myService.getData());
    }
 };
});

app.factory('myService', function() {
var _data=[];    
return {
    setData: function(value){
        for (var a=0;a<value.length;a++){
            _data.push(value[a]);
        }
    },
    getData: function(){
        return _data
    }            
}
});

https://jsfiddle.net/devonCream/ess9d6q6/

Unfortunately, I cannot share the actual code for confidentiality reasons. However, imagine that instead of passing in a hardcoded value, I am fetching data from a URL through a service and storing it in an array within the factory. With each execution, the data keeps accumulating! This code serves as a demonstration.

javascript angularjs oop controller singleton

Answer 1

Answer №1

If you are looking to create a custom drop-down feature, it is recommended to implement it as a directive for better organization. There are various methods to achieve the desired functionality using a directive. You can refer to the directive walkthroughs for additional guidance.

It is advisable to incorporate an isolate scope, utilize a template, and include a link function in your directive implementation.

One approach involves having preset items:

angular.module('myApp')
    .directive('myDropdown', function () {
        return {

            scope: {},

            template: '' +
                '<div class="my-dropdown">' +
                    '<div class="my-dropdown-item" ng-repeat="item in items">{{item.text}}</div>' +
                '</div>',

            link: function (scope, element, attrs) {
                scope.items = ['Item 1', 'Item 2', 'Item 3'];
            }

        };
    });

Alternatively, you can pass the items dynamically to each instance:

angular.module('myApp')
    .directive('myDropdown', function () {
        return {

            scope: {
                items: '='
            },

            template: '' +
                '<div class="my-dropdown">' +
                    '<div class="my-dropdown-item" ng-repeat="item in items">{{item.text}}</div>' +
                '</div>'

        };
    });

--UPDATE--

Here is an example where data is fetched once from a service:

angular.module('myApp')
    .service('dataService', function ($http) {
        var items;

        $http.get('http://ab.com/dropdown-items')
        .then(function (res) {
            items = res.data;
        });

        return {
            items: items
        };
    })
    .directive('myDropdown', function (dataService) {
        return {

            scope: {},

            template: '' +
                '<div class="my-dropdown">' +
                    '<div class="my-dropdown-item" ng-repeat="item in items">{{item.text}}</div>' +
                '</div>',

            link: function (scope, element, attrs) {
                scope.items = dataService.items;
            }

        };
    });

Answer 2

If you are looking to create a custom drop-down feature, it is recommended to implement it as a directive for better organization. There are various methods to achieve the desired functionality using a directive. You can refer to the directive walkthroughs for additional guidance.

It is advisable to incorporate an isolate scope, utilize a template, and include a link function in your directive implementation.

One approach involves having preset items:

angular.module('myApp')
    .directive('myDropdown', function () {
        return {

            scope: {},

            template: '' +
                '<div class="my-dropdown">' +
                    '<div class="my-dropdown-item" ng-repeat="item in items">{{item.text}}</div>' +
                '</div>',

            link: function (scope, element, attrs) {
                scope.items = ['Item 1', 'Item 2', 'Item 3'];
            }

        };
    });

Alternatively, you can pass the items dynamically to each instance:

angular.module('myApp')
    .directive('myDropdown', function () {
        return {

            scope: {
                items: '='
            },

            template: '' +
                '<div class="my-dropdown">' +
                    '<div class="my-dropdown-item" ng-repeat="item in items">{{item.text}}</div>' +
                '</div>'

        };
    });

--UPDATE--

Here is an example where data is fetched once from a service:

angular.module('myApp')
    .service('dataService', function ($http) {
        var items;

        $http.get('http://ab.com/dropdown-items')
        .then(function (res) {
            items = res.data;
        });

        return {
            items: items
        };
    })
    .directive('myDropdown', function (dataService) {
        return {

            scope: {},

            template: '' +
                '<div class="my-dropdown">' +
                    '<div class="my-dropdown-item" ng-repeat="item in items">{{item.text}}</div>' +
                '</div>',

            link: function (scope, element, attrs) {
                scope.items = dataService.items;
            }

        };
    });

Answer 3

Answer №2

After much contemplation, I have come to the conclusion that the most effective solution to this issue is to store the data in the controller itself. This approach ensures that the data remains isolated within its own controller instance, preventing any potential conflicts.

In my revised 'fiddle', I have demonstrated how utilizing two different data sources (represented by two factories acting as models) can bring the data back into the controller for processing and storage.

Typically, if I were not reusing the component, I would integrate this logic into the factory. However, doing so only leads me back to the initial problem I encountered.

Furthermore, in my actual project, I perform checks on variables to determine which 'instance' has been triggered, allowing me to call methods accordingly. Although this process may seem cumbersome, it appears to be the most reliable approach until Angular 2 resolves these issues.

Here is the link to my updated jsfiddle

    var app = angular.module('myApp',[]);

app.directive('mySelector', function () {
return { 
    scope: true,
    bindToController:  {
        mydata: '@mydata',     
        timePeriodOptions: '='
    },
    controllerAs: 'selCtrl',
    restrict: 'EA',
    template:'<select ng-model="timePeriodSelection" ng-options="timePeriodOption.name for timePeriodOption in selCtrl.timePeriodOptions"><option value="">Choose time period</option></select>',
    controller: 'selCtrl'
 };
});    
app.controller('selCtrl', function($scope, myService) {
    var selCtrl = this;    
    selCtrl.timePeriodOptions = [];
    if (angular.isString(selCtrl.mydata)){
        processData();
    }
    function processData(){
        var value = myService.getData(selCtrl.mydata);
        for (var a=0;a<value.length;a++){
            selCtrl.timePeriodOptions.push(value[a]);
        }
    };
});

app.factory('myService', function(dataModel1,dataModel2) {
return {
    getData: function(model){
        var _data = []        
        if (model === "1"){
            _data = dataModel1.getData();
        }else{
            _data = dataModel2.getData();
        }
        console.log('data ',_data);
        return _data
    }            
    }
});
app.factory('dataModel1', function() {
    var _data=[{"name":1,"value":1},{"name":2,"value":2},{"name":3,"value":3}];    
    return {
        getData: function(){
            return _data
        }            
    }
});
app.factory('dataModel2', function() {
    var _data=[{"name":4,"value":4},{"name":5,"value":5},{"name":6,"value":6}];    
    return {
        getData: function(){
            return _data
        }            
    }
});

Answer 4

After much contemplation, I have come to the conclusion that the most effective solution to this issue is to store the data in the controller itself. This approach ensures that the data remains isolated within its own controller instance, preventing any potential conflicts.

In my revised 'fiddle', I have demonstrated how utilizing two different data sources (represented by two factories acting as models) can bring the data back into the controller for processing and storage.

Typically, if I were not reusing the component, I would integrate this logic into the factory. However, doing so only leads me back to the initial problem I encountered.

Furthermore, in my actual project, I perform checks on variables to determine which 'instance' has been triggered, allowing me to call methods accordingly. Although this process may seem cumbersome, it appears to be the most reliable approach until Angular 2 resolves these issues.

Here is the link to my updated jsfiddle

    var app = angular.module('myApp',[]);

app.directive('mySelector', function () {
return { 
    scope: true,
    bindToController:  {
        mydata: '@mydata',     
        timePeriodOptions: '='
    },
    controllerAs: 'selCtrl',
    restrict: 'EA',
    template:'<select ng-model="timePeriodSelection" ng-options="timePeriodOption.name for timePeriodOption in selCtrl.timePeriodOptions"><option value="">Choose time period</option></select>',
    controller: 'selCtrl'
 };
});    
app.controller('selCtrl', function($scope, myService) {
    var selCtrl = this;    
    selCtrl.timePeriodOptions = [];
    if (angular.isString(selCtrl.mydata)){
        processData();
    }
    function processData(){
        var value = myService.getData(selCtrl.mydata);
        for (var a=0;a<value.length;a++){
            selCtrl.timePeriodOptions.push(value[a]);
        }
    };
});

app.factory('myService', function(dataModel1,dataModel2) {
return {
    getData: function(model){
        var _data = []        
        if (model === "1"){
            _data = dataModel1.getData();
        }else{
            _data = dataModel2.getData();
        }
        console.log('data ',_data);
        return _data
    }            
    }
});
app.factory('dataModel1', function() {
    var _data=[{"name":1,"value":1},{"name":2,"value":2},{"name":3,"value":3}];    
    return {
        getData: function(){
            return _data
        }            
    }
});
app.factory('dataModel2', function() {
    var _data=[{"name":4,"value":4},{"name":5,"value":5},{"name":6,"value":6}];    
    return {
        getData: function(){
            return _data
        }            
    }
});

Utilizing Angular Directives and Controllers for Improved Efficiency

Answer №1

Answer №2

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