Injecting without constructor

[Paulo Coutinho]

Hi,

When you create a service that have global properties, like:

import {Injectable} from "angular2/core";


@Injectable()
export class MyService {
    private myValue;


    constructor() {}


    setValue(val) {
        this.myValue = val;
    }


    getValue(val) {
        return this.val;
    }
}

And you need access it globally from your app initialising:

import {MyService} from './services/my.service';
bootstrap(App, [MyService, COMMON_DIRECTIVES, ROUTER_DIRECTIVES, ROUTER_PROVIDERS, HTTP_PROVIDERS]); // directives added here are available to all children

And you need access it from your component:

import {MyService} from '../services/my.service';


@Component({
    selector: 'some-component',
    template: `
<div>MyValue: {{val}}</div>
`
})
export class SomeComponent {
    constructor(private myService:MyService) {
    }


    get val() {
        return this.myService.getValue();
    }
}

You always create a constructor with private variable creation as the custom service. No problem here.

My question is about the possibility of create the component, with the services injected, but without a constructor and private param.

Thanks.

[Sander Elias]

Hi Paulo.

May I ask for your use-case? do you wan't/need some kind of global?

I'm not aware of a way to do it through the injector. However, it is possible to create a real singleton service(that you can use in and outside angular), that you put into the global space. 

regards

Sander

[Paulo Coutinho]

Hi,

I need a global service with variables that dont change across the application.

You can see my project as an example:

https://github.com/prsolucoes/gohc

I have on header the count/list of running jobs. I need that every second this new informations change on this global service and this information will be used to show the list of running jobs too.

Thanks.

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[Lucas Lacroix]

My understanding is that all injected dependencies are singletons.

So, if you inject the same type of thing in multiple places, you should receive the single instance of that thing.

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Lucas Lacroix

Computer Scientist

System Technology Division, MEDITECH

781-774-2293

[Paulo Coutinho]

Ok,

But the question is about receiving this "injection". 

The only way to inject my global service is from the constructor? Or i can create a component with any constructor and on "OnInit" i set "this.myService = ???".

Thanks.

Atenciosamente, 

Paulo Coutinho.

PRS - Soluções Inteligentes

Site: www.prsolucoes.com

Blog: www.pcoutinho.com 
Skype: paulo.prsolucoes

Telefone: +55 21 99386-0010

[Lucas Lacroix]

It sounds like you want to inject the service into all components, which isn't possible to do automatically and, I would argue, would be very bad.

You have to reference the injectable in your component's constructor.

The other solution, as Sander said, is to create your service in the global namespace (ex. "window.myGlobalService = ...") and you can then reference it everywhere.