Angular5: Return HttpClient response from a service to a Component?

问题

I currently learning Angular 5 and I'm having difficulty on passing data from a service to a component. I'm integrating this to wordpress..

here's my current code:
orderers.component.ts

import { Component, OnInit } from '@angular/core';
import { HttpClient, HttpHeaders } from '@angular/common/http';

@Component({
    selector: 'app-orderer',
    templateUrl: './orderer.component.html',
    styleUrls: ['./orderer.component.css'] })


export class OrdererComponent implements OnInit {

o_manual:boolean = false;
orderers = [];

constructor(private http:HttpClient) { }

ngOnInit() {
    this.get_users();
}

get_users() {
    this.http.get('http://angular5.localhost/wp-admin/admin-ajax.php?action=orderers').subscribe( data => { 
        this.orderers = data;
    }
} }

how can i transfer get_user() to a service and return the data and pass it in the component ? Thanks .. :)

回答1:

First create service and copy your get_users() function. Every http request return an Object of type Observable, this is the object that contains the subscribe() function, you need to return it in the get_users() function. something like :

    @Injectable()
    export class SomeNameService {

      constructor(private http: HttpClient) {

      }

      get_users():Observable<any> {
        return this.http.get('http://angular5.localhost/wp-admin/admin-ajax.php?action=orderers');
    }
}

now in your Module you need to list this service under the providers

@NgModule({
  imports: [...],
  declarations: [...],
  providers: [SomeNameService]
})

after that you need to inject it into your component just like you injected HttpClient, and subscribe to your get_users() function.

constructor(private someService:SomeNameService) { }
ngOnInit(){
 this.someService.get_users().subscribe(data=>{
    this.orderers = data;
  });
}

by the way there are great examples on angular.io https://angular.io/tutorial/toh-pt4

hope this was helpful

回答2:

Step 1 Create your service and place your function inside

get_users_from_service(): Observable<any> {   
   return this.http.get(...)     // You can also try to catch any exception here
}

Step 2 Call your service in the component after injecting it in the constructor

get_users() {
   this.nameOfService.get_users_from_service().subscribe(data => {
      this.orderers = data;
   },
   error => {
       // Do something with error
   }
}

来源：https://stackoverflow.com/questions/47507179/angular5-return-httpclient-response-from-a-service-to-a-component

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