this.http.get不是angular8函数

Question

I want to display list of users using service use angular 8

data-service.service

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs' ;
import { HttpClientModule } from '@angular/common/http';
import 'rxjs/add/operator/map';

    @Injectable({
      providedIn: 'root'})
    export class DataServiceService {
      constructor(public http:HttpClientModule) {}
      getPersone(){
        return this.http.get('https://jsonplaceholder.typicode.com/users').map(res=>res.json);
      }
    }

app.module.ts

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/Forms';
import {DataServiceService} from './services/data-service.service' ;
//import { HttpModule } from '@angular/Http';
import { HttpClientModule } from '@angular/common/http';

import { AppComponent } from './app.component';
import { NajibComponent } from './components/najib/najib.component';
import { EventsComponent } from './components/events/events.component';
import { CeventsComponent } from './components/cevents/cevents.component';
import { FormsComponent } from './components/forms/forms.component';
import { SComponentComponent } from './components/s-component/s-component.component';
import { from } from 'rxjs';
import { Server } from 'net';

@NgModule({
  declarations: [
    AppComponent,
    NajibComponent,
    EventsComponent,
    CeventsComponent,
    FormsComponent,
    SComponentComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
   // HttpModule
   HttpClientModule

  ],
  providers: [],
  bootstrap: [AppComponent]

})
export class AppModule { }

s-component.component.ts

import { Component, OnInit } from '@angular/core'; 
import { DataServiceService } from '../../services/data-service.service';

@Component({
  selector: 'app-s-component',
  templateUrl: './s-component.component.html',
  styleUrls: ['./s-component.component.css']
})
export class SComponentComponent implements OnInit {

  users:any[]=[];
  constructor(public dataService:DataServiceService) {
  this.dataService.getPersone().subscribe(users=>{
        this.users=users;
  });
   }
  ngOnInit() {  
  }
}

s-component.component.html

<div class="container">
<p>s-component works!</p>

    <ul >
        <li *ngFor="let item of users">
            {{ item.id }}
        </li>
    </ul>

</div>

Answer 1

You need to use constructor(private http: HttpClient)

In your DataServiceService :

import { HttpClient } from '@angular/common/http';

and inject same in constructor .

You should be injecting HttpClient to your service NOT the HttpClientModule in your DataServiceService .

Answer 2

First you need to import import { HttpClientModule } from '@angular/common/http'; in your main module you done that so now you need to in same module declare your service DataServiceService but in providers array.

Module:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { DataService } from './shared/data.service';
import { HttpClientModule } from '@angular/common/http';
import { CComponentComponent } from './c-component/c-component.component';

@NgModule({
  declarations: [
    AppComponent,
    CComponentComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    HttpClientModule,
  ],
  providers: [
    DataService // < here is your own data service
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

Service:

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';

@Injectable({
  providedIn: 'root'
})
export class DataService {

  constructor(private http: HttpClient) { }

  getUsers() {
    return this.http.get('https://jsonplaceholder.typicode.com/users')
  }

}

component.ts:

import { Component, OnInit } from '@angular/core';
import { DataService } from '../shared/data.service';
import { Observable } from 'rxjs';

@Component({
  selector: 'app-c-component',
  templateUrl: './c-component.component.html',
  styleUrls: ['./c-component.component.scss']
})
export class CComponentComponent implements OnInit {

  users: Observable<any>

  constructor(private data: DataService) { }

  ngOnInit() {
    this.users = this.data.getUsers()
  }

}

component.html :

<div class="container">
  <p>c-component works!</p>
  <ul>
    <li *ngFor="let user of users | async">
      {{ user.id }}
    </li>
  </ul>
</div>

In your service you no need to call res.json If you really need response as a json. you can call it in your template like {{ user | json }} {{ user | json }} and it will display objects as a json file. As a response from http call in your service you getting an Observable<any> value. To ret rave data from that observable you need to subscribe to it or call pipe in your template like above users | async users | async . This pipe will manage the subscription for you so you no need do that.