Angular 2: Implementing http service for delete

Question

I am trying to write a service for deleting from my external db and I keep seeing this error:

The type argument for type parameter 'T' cannot be inferred from the usage. Consider specifying the type arguments explicitly. Type argument candidate 'Response' is not a valid type argument because it is not a supertype of candidate 'Response'. Types of property 'type' are incompatible. Type 'string' is not assignable to type 'ResponseType'.

^ and this error highlights the line:

return this.http.delete(`${this.base_url}/${id}`)

Here is the service:

import { Injectable } from '@angular/core';
import { CheckIn } from './check-in';
import { Headers, RequestOptions, Http } from '@angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/map';


@Injectable()

export class CheckInService {

  private base_url = "http://localhost:3000/";

  constructor (private http: Http) {}

  delete(id:string): Observable<CheckIn[]> {

    return this.http.delete(`${this.base_url}/${id}`)
                    .map((res:Response) => res.json()) .json() on the response to return data
                     .catch((error:any) => Observable.throw(error.json().error || 'Server error')); 
  }
}

What am I doing wrong?

Arun Sivan · Accepted Answer · 2017-05-11 13:14:32Z

1

Try this sample code. I think problem is with the way you are accepting your response.

Main Code

import { Component, OnInit } from "@angular/core";
import {CheckInService} from "../shared/checkin.service";
@Component({
 selector: "test",
 templateUrl: "./test.html",
 styleUrls: ["./test.css"]
})
export class TestComponent implements OnInit{

dataMap:any;
dataDeleteMap:any;
constructor(public dataMapService:CheckInService) {
    this.dataMapService=dataMapService;
}
ngOnInit(){}

  deleteField(id:string){
    this.dataMapService.deleteField(id).subscribe(jsonData=>{
    this.dataDeleteMap=jsonData;
  }); 
 }
}

Service

import { Injectable ,OnInit,OnDestroy} from '@angular/core';
import { Http, Response,Headers,RequestOptions} from '@angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/Rx';
import 'rxjs/add/operator/map';

@Injectable()
export class CheckInService {

data:any;
baseUrl:string='http://localhost:3000/';

constructor(public http:Http) { 
}

 deleteField(id:string):Observable<Response>{
   return this.http.delete(`${this.baseUrl}/${id}`)
   .map(result=>result.json());
 }
}

edited May 11, 2017 at 13:14

answered May 10, 2017 at 20:27

Arun Sivan

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2 Comments

Jeremy Thomas Over a year ago

I'm trying to implement this, but I'm still not sure what t is supposed to be when I make the call to deleteField()

Arun Sivan Over a year ago

it was a mistake. t is not needed now you can try the code.

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