Separate files containing TypeScript decorators are defined within a project

(Let's dive into Typescript and Angular2, shall we?)

Having primarily coded in Symfony2 with annotations, I found it convenient to configure entity mapping, routing, and other features using yaml, xml, or plain PHP. This flexibility was great for creating code that could stand alone as a library or easily integrate with Symfony.

Then, when I started exploring Angular2 and TypeScript, I discovered the use of decorators for everything - component metadata, services, you name it.

But what if I want to prepare a class that can be reused with different frameworks? For example, when creating a service for my app, it needs to be marked as injectable in Angular2. Is there a way to add a decorator separately so that I can inject an external class into Angular2's DI system?

typescriptangular

Answer №1

If you wish to incorporate something into your class, using the @Injectable decorator is necessary. This indicates a dependence on Angular2 for its injection capabilities.

However, if you have no intention of injecting anything, there is no need for this decorator when linking classes together.

For more information, please refer to the following question:

  • Angular2: Inject a non @Injectable class

Answer №2

If you're looking to inject a class with dependencies without using @Injectable(), consider utilizing a factory instead.

bootstrap(AppComponent, [
    SomeDep, 
    provide(SomeType, {useFactory: (dep) => new SomeType(dep), 
        deps: [SomeDep]})
]);

To simplify this process and make providers more reusable, you can create variables for them (similar to how HTTP_PROVIDERS is used).

export const SOME_TYPE_PROVIDERS: any[] = [
  SomeDep, 
  provide(SomeType, {useFactory: (dep) => new SomeType(dep), 
      deps: [SomeDep]})
];

This allows you to easily incorporate these providers by simply referencing the variable.

bootstrap(AppComponent, [SOME_TYPE_PROVIDERS]);

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