ngOnInit() not getting trigged

Question

I have the following files:

/src/app/app.module.ts

...
@NgModule({
    ...
    providers: [
        StatusBar,
        SplashScreen,
        Storage,
        ConfigService,
        AuthService,
        TodoService,
    ]
    ...
})
export class AppModule { }

/src/providers/config.service.ts

import { Injectable } from '@angular/core';

export interface HashTable<T> {
    [key: string]: T;
}

@Injectable()
export class ConfigService {

    config: HashTable<String> = {
        'baseUrl': 'http://127.0.0.1:8080',
    };

    constructor() { }

    getConfig(): HashTable<String> {
        return this.config;
    }

}

/src/providers/todo.service.ts

import { Injectable, OnInit } from '@angular/core';
import { Http, Headers } from '@angular/http';
import { ConfigService, HashTable } from './config.service';
import { AuthService } from './auth.service';
import 'rxjs/add/operator/map';

@Injectable()
export class TodoService implements OnInit {

    config: HashTable<String>;

    constructor(private http: Http, private configService: ConfigService, private authService: AuthService) {
        // this.getConfig();
    }
    ngOnInit() {
        this.getConfig();
    }
    getConfig(): void {
        this.config = this.configService.getConfig();
    }
    getTodos() {
        return new Promise((resolve, reject) => {
            let headers = new Headers();
            headers.append('Authorization', this.authService.token);
            this.http
                .get(
                    this.config['baseUrl'] + '/api/todos',
                    { headers: headers }
                )
                .map(res => res.json())
                .subscribe(
                    data => {
                        resolve(data);
                    },
                    err => {
                        reject(err);
                    }
                );
        });
    }
}

In the file: todo.service.ts...

The ngOnInit() is not getting trigged. I need this to get trigged in order that the method: this.getConfig() get called.

In the other hand, if I uncomment the line inside the constructor (same file) everything works fine but I don't want that way because I hope the ngOnInit get called. I have read on some places that you should call the service load, in this case: this.getConfig(); inside the ngOnInit.

My goal with all this is to use a file to store configuration values for the application. Actually this code works fine if I uncomment the line inside the constructor but I'm trying to get adjusted to the standards.

Any idea on this?

Thanks.

i think ngOnInit is not lifecycle of services it can be used only in module or components. — Javascript Hupp Technologies, Mar 23 '18 at 05:01
Angular service doesn't own lifehook like component. You can do initialization things in `constructor`. — Pengyy, Mar 23 '18 at 05:02

score 3 · Accepted Answer · answered Mar 23 '18 at 05:06

3

OnInit() work with Directives and Components. They do not work with other types, like a service. It doesn't work with Injectable classes. Your code doesn't works with Lifecycle hooks .

answered Mar 23 '18 at 05:06

ZearaeZ

899
8
20

Happy coding :) – ZearaeZ Mar 23 '18 at 05:20

score 0 · Answer 2 · answered Mar 23 '18 at 05:07

0

ngOnInit() will not work with service.

Same is explained ngOnInit not being called when Injectable class is Instantiated

answered Mar 23 '18 at 05:07

Lakshmi Prasanna

440
4
16

ngOnInit() not getting trigged

2 Answers2