How could I inject service into a function?

Question

var someObject = {
  func: (http: Http)=>{
    // do something
  }
}

---------------------------------------------

// somewhere in an ng2 module
function injectServices(theObject){

  let services = getServices(theObject.func)

  //inject services into theObject
  ....

}

// return services
function getServices(func: Function){
   // get params' type of func
   let paramTypes = ...
   // get services' singleton
   let singletons = ...

   return singletons;
}

Does Reflect provides such method so that I can get params' type of a function? How could I get the service classes' singleton?

The scenario is I will take an object which implements the interface below to render a form view and I have some custom services that should be injected into $validator, $parser, and $formatter at runtime.

interface IViewSchema {
  "title": String,
  "buttons": [
    {
      "buttonText": String,
      "role?": "cancel" | "submit",
      "callback?": 'cancel' | 'submit' | Function,
      "disabled": String
    }
  ],
  "viewTemplate?": String,
  "formControls?": [
    {
      "formTemplate?": String,
      "label": String,
      "maxLength?": number, // max length of input
      "minLength?": number, // min length of input
      "hidden?": String, // if hidden is true, hide the form control
      "disabled?": String, // if data is editable or not, default true,
      "placeholder?": String,
      "model?": String,
      "$validate?":Function[],
      "$parser?": { // parse modal data to view data
        "async?": boolean, // default false, run async parser or not
        "remote?": { // enabled only when async is true
          "url": String, // remote url
          "method?": String, // calling method
          "headers?": JSON, 
          "body?": String | JSON
        },
        "parse?": Function
      },
      "$formatter?": Function
    }
  ]
}

No. Angular DI injects only into the constructor of classes. — Günter Zöchbauer, Sep 30 '16 at 08:51
then is there any way I can get the function's param types through Reflect?? — Woods Geroge, Sep 30 '16 at 08:58
Sorry, I don't know about that. Why don't you just make it a class and let Angular2 do the job? — Günter Zöchbauer, Sep 30 '16 at 08:59
The thing is I am trying to use a single template component to reduce the complexity of building new form component. — Woods Geroge, Sep 30 '16 at 09:36
Sounds quite weird to me. Why does `$validator`, `$parser`, `$formatter` have to be functions instead of a methods of `IViewSchema`. If you inject services into `ViewSchemaImpl` then all methods can access the services (properties of `ViewSchemaImpl`). — Günter Zöchbauer, Sep 30 '16 at 09:40
I could look for possible solution here: https://github.com/angular/angular/blob/42a287fabf6b035d51e00cf3006c27fec00f054a/modules/%40angular/core/src/util/decorators.ts — Roman Kolesnikov, Sep 30 '16 at 11:38

score 0 · Answer 1 · answered Jul 19 '17 at 12:57

I faced with the same issue on my project. We are using Angular 4 + Redux. Here is how I solve it:

import { AppActions } from '../app.actions';
import { IAction } from './model.interface';
import { SomeService} from '../services/some.service';

const someService = new SomeService();

export function someReducer(reducersKey) {
   return function (state: IState = INITIAL_STATE,
                    action: IAction): IState {
if (action.type === AppActions.REHYDRATE) {
  if (action.payload) {

const newState = someService.awesomeMethod();

    return {...state, ...newState};
  }
  return state;
 }
 return state;
};

How could I inject service into a function?

1 Answers1