TypeScript and Angular: Harnessing the Power of Directive Dependency Injection

There are multiple approaches to creating Angular directives in TypeScript. One elegant method involves using a static factory function:

module app {
    export class myDirective implements ng.IDirective {
        restrict: string = "E";
        replace: boolean = true;
        templateUrl: string = "my-directive.html";

        link: ng.IDirectiveLinkFn = (scope: ng.IScope, el: ng.IAugmentedJQuery, attrs: ng.IAttributes) => {
        };

        static factory(): ng.IDirectiveFactory {
            var directive: ng.IDirectiveFactory = () => new myDirective();
            return directive;
        }
    }

    angular.module("app")
        .directive("myDirective", myDirective.factory());
}

However, if you need to inject dependencies such as $timeout, the process becomes more complex:

module app {
    export class myDirective implements ng.IDirective {
        restrict: string = "E";
        replace: boolean = true;
        templateUrl: string = "my-directive.html";

        constructor(private $timeout: ng.ITimeoutService) {
        }

        link: ng.IDirectiveLinkFn = (scope: ng.IScope, el: ng.IAugmentedJQuery, attrs: ng.IAttributes) => {
            // using $timeout
             this.$timeout(function (): void {
             }, 2000);
        }

        static factory(): ng.IDirectiveFactory {
            var directive: ng.IDirectiveFactory = () => new myDirective(); 
            directive.$inject = ["$timeout"];
            return directive;
        }
    }

    angular.module("app")
        .directive("myDirective", myDirective.factory());
}

The challenge lies in properly calling the myDirective constructor and passing in $timeout.

Answer №1

To set a specific timeout, simply include $timeout as an argument in the factory constructor function and pass it along.

   static createFactory(): ng.IDirectiveFactory {
        var directive: ng.IDirectiveFactory = 
                       ($timeout:ng.ITimeoutService) => new myCustomDirective($timeout); 
        directive.$inject = ["$timeout"];
        return directive;
    }

Answer №2

Despite the presence of an official answer, I'd like to share my perspective.. Some time back, I encountered a similar issue with directives as well as filters (which Angular associates with filter factories). To address this, I developed a concise library leveraging standard type definitions that allowed me to create something along these lines (omitting controlled and template code):

@Directive('userRank')
export class UserRankDirective implements ng.IDirective {

    controller = UserRankDirectiveController;
    restrict = 'A';
    template = template;
    //controllerAs: 'ctrl', set as default
    replace = true;
    scope = {
        user: '=userRank'
    }

    constructor($q: ng.IQService) {
        console.log('Q service in UserRankDirective:', $q);
    }

}

To enable this functionality, I had to tailor the TypeScript code emitter so that it generates interface metadata (ensuring that ng.IQService is accessible at runtime and corresponds to '$q' in the constructor array); this metadata is utilized by the @Directive decorator for registering the directive within the application module using this piece of code. Feel free to explore the sample application's code here.

Answer №3

After encountering a similar issue, I managed to resolve it by creating a Util class named "ComponentRegistrator" (inspired by the insights shared on this webpage):

/// <reference path="../../../Typings/tsd.d.ts"/>
module Common.Utils {
    "use strict";

    export class ComponentRegistrator {
        public static regService(app: ng.IModule, name: string, classType: Function) {
            return app.service(name, classType);
        }

        public static regController(app: ng.IModule, name: string, classType: Function) {
            var factory: Function = Component.reg(app, classType);
            return app.controller(name, factory);
        }

        public static regDirective(app: ng.IModule, name: string, classType: Function) {
            var factory: Function = Component.reg(app, classType);
            return app.directive(name, <ng.IDirectiveFactory>factory);
        }

        private static reg<T extends ng.IDirective>(app: ng.IModule, classType: Function) {
            var factory: Function = (...args: any[]): T => {
                var o = {};
                classType.apply(o, args) || console.error("Return in ctor missing!");
                return <T> o;
            };
            factory.$inject = classType.$inject || [];
            return factory;
        }
    }
}

One example of its usage is as follows:

/// <reference path="../../../Typings/tsd.d.ts"/>
///<reference path="../../Common/Utils/Component.ts"/>

module Sample {
    "use strict";

    class SampleDirective implements ng.IDirective {
        public static $inject: string[] = [];

        public templateUrl: string;
        public scope: {};
        public restrict: string;
        public require: string;
        public link: ng.IDirectiveLinkFn;

        constructor() {
            this.templateUrl = "/directives/sampleDirective.html";
            this.restrict = "A";
            this.scope = {
                element: "=",
            };
            this.link = this.linker;
            return this; // important!
        }

        private linker = (scope: IExpressionConsoleScope): void => {
            // ...
        };
    }

    ComponentRegistrator.regDirective(app, "directiveName", SampleDirective);
}

Note the return this in the constructor and the static $inject. It's essential to specify the inject as recommended by PSL:

// ...
class SampleDirective implements ng.IDirective {
    public static $inject: string[] = ["$timeout"];
// ...
constructor(private $timeout:ng.ITimeoutService) {
// ...

By following this approach, you can prevent the duplication of the factory method and consistently apply the same pattern...

Answer №4

In my humble opinion, here is a slightly simpler version:

export var SimpleComponent = ($timeout: any): ng.IDirective => {
  return {
    controller,
    controllerAs: 'vm',
    restrict: 'E',
    templateUrl: 'components/simpleTemplate/simpleTemplate.html',
    scope: {
      simpleAttribute: '@'
    },
    link: {
      post: (scope, elem, attr, ctrl) => {
        console.log('You should be able to see this:', $timeout);
      }
    }
  };
}

SimpleComponent.$inject = ['$timeout'];

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