Angular HTTP GET with TypeScript error http.get(…)

Question

I have a problem with HTTP in Angular.

I just want to GET a JSON list and show it in the view.

Service class

import {Injectable} from "angular2/core";
import {Hall} from "./hall";
import {Http} from "angular2/http";
@Injectable()
export class HallService {
    public http:Http;
    public static PATH:string = 'app/backend/'    

    constructor(http:Http) {
        this.http=http;
    }

    getHalls() {
           return this.http.get(HallService.PATH + 'hall.json').map((res:Response) => res.json());
    }
}

And in the HallListComponent I call the getHalls method from the service:

export class HallListComponent implements OnInit {
    public halls:Hall[];
    public _selectedId:number;

    constructor(private _router:Router,
                private _routeParams:RouteParams,
                private _service:HallService) {
        this._selectedId = +_routeParams.get('id');
    }

    ngOnInit() {
        this._service.getHalls().subscribe((halls:Hall[])=>{ 
            this.halls=halls;
        });
    }
}

However, I got an exception:

TypeError: this.http.get(...).map is not a function in [null]

hall-center.component

import {Component} from "angular2/core";
import {RouterOutlet} from "angular2/router";
import {HallService} from "./hall.service";
import {RouteConfig} from "angular2/router";
import {HallListComponent} from "./hall-list.component";
import {HallDetailComponent} from "./hall-detail.component";
@Component({
    template:`
        <h2>my app</h2>
        <router-outlet></router-outlet>
    `,
    directives: [RouterOutlet],
    providers: [HallService]
})

@RouteConfig([
    {path: '/',         name: 'HallCenter', component:HallListComponent, useAsDefault:true},
    {path: '/hall-list', name: 'HallList', component:HallListComponent}
])

export class HallCenterComponent{}

app.component

import {Component} from 'angular2/core';
import {ROUTER_DIRECTIVES} from "angular2/router";
import {RouteConfig} from "angular2/router";
import {HallCenterComponent} from "./hall/hall-center.component";
@Component({
    selector: 'my-app',
    template: `
        <h1>Examenopdracht Factory</h1>
        <a [routerLink]="['HallCenter']">Hall overview</a>
        <router-outlet></router-outlet>
    `,
    directives: [ROUTER_DIRECTIVES]
})

@RouteConfig([
    {path: '/hall-center/...', name:'HallCenter',component:HallCenterComponent,useAsDefault:true}
])
export class AppComponent { }

tsconfig.json

{
  "compilerOptions": {
    "target": "ES5",
    "module": "system",
    "moduleResolution": "node",
    "sourceMap": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "removeComments": false,
    "noImplicitAny": false
  },
  "exclude": [
    "node_modules"
  ]
}

Answer 1

Global import is safe to go with.

import 'rxjs/Rx';

Answer 2

Angular 6 - only import 'rxjs/Rx' did the trick for me

Answer 3

I tried below commands and it gets fixed:

npm install rxjs@6 rxjs-compat@6 --save


import 'rxjs/Rx';

Answer 4

Angular version 6 "0.6.8" rxjs version 6 "^6.0.0"

this solution is for :

  "@angular-devkit/core": "0.6.8",
  "rxjs": "^6.0.0"

as we all know angular is being developed every day so there are lots of changes every day and this solution is for angular 6 and rxjs 6
first to work with http yo should import it from : after all you have to declare the HttpModule in app.module.ts

import { Http } from '@angular/http';

and you have to add HttpModule to Ngmodule -> imports

  imports: [
    HttpModule,
    BrowserModule,
    FormsModule,
    RouterModule.forRoot(appRoutes)
  ],

second to work with map you should first import pipe :

import { pipe } from 'rxjs';

third you need the map function import from :

import { map } from 'rxjs/operators';

you have to use map inside pipe like this exemple :

 constructor(public http:Http){  }

    getusersGET(){
        return this.http.get('http://jsonplaceholder.typicode.com/users').pipe(
         map(res => res.json()  )  );
    }

that works perfectly good luck !

Answer 5

From rxjs 5.5 onwards, you can use the pipeable operators

import { map } from 'rxjs/operators';

What is wrong with the import 'rxjs/add/operator/map';

When we use this approach map operator will be patched to observable.prototype and becomes a part of this object.

If later on, you decide to remove map operator from the code that handles the observable stream but fail to remove the corresponding import statement, the code that implements map remains a part of the Observable.prototype.

When the bundlers tries to eliminate the unused code (a.k.a. tree shaking), they may decide to keep the code of the map operator in the Observable even though it’s not being used in the application.

Solution - Pipeable operators

Pipeable operators are pure functions and do not patch the Observable. You can import operators using the ES6 import syntax import { map } from "rxjs/operators" and then wrap them into a function pipe() that takes a variable number of parameters, i.e. chainable operators.

Something like this:

getHalls() {
    return this.http.get(HallService.PATH + 'hall.json')
    .pipe(
        map((res: Response) => res.json())
    );
}