The error message "result.subscribe is not a function" indicates that there was a problem

I encountered an issue with the following error message:

Uncaught TypeError: result.subscribe is not a function

Here's a screenshot of the error for reference:

https://i.sstatic.net/yfhy0.png

Despite attempting to handle the error, I'm still struggling. Below is the snippet of my code.

login.component.ts:

import { Component } from '@angular/core';
import { UserService } from '../../services/user.service';
import { User } from '../../models/user';
import {ToasterContainerComponent, ToasterService, ToasterConfig} from 'angular2-toaster/angular2-toaster';

@Component({
    moduleId: module.id,
    selector: 'login',
    directives: [ToasterContainerComponent],
    templateUrl: 'login.component.html',
    providers: [UserService, ToasterService]
})

export class LoginComponent {
    user: User = new User();
    loginRes: String;
    private toasterService: ToasterService;

    public toasterconfig: ToasterConfig = new ToasterConfig({
        showCloseButton: true,
        tapToDismiss: false,
        timeout: 0
    });

    constructor(private _userService: UserService, toasterService: ToasterService) {
        this.toasterService = toasterService;
    }

    data = {};
    onSubmit() {
        this._userService.login(this.user)
            .subscribe(
                res => {
                    console.log("res onSubmit");
                    console.log(res);
                },
                function(error) { console.log("Error happened" + error)}
            );
    }
}

user.service.ts:

import { Injectable } from '@angular/core';
import { Headers, RequestOptions, Http, Response } from '@angular/http';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';
import { User } from '../models/user';

@Injectable()
export class UserService {
    private loginUrl: string;

    constructor(private _http: Http) {

    }

    login(user: User) {
        this.loginUrl = "http://localhost:3000/api/auth/login";
        let data = { "username": user.username, "password": user.password };
        let body = JSON.stringify(data);
        let headers = new Headers({ 'Content-Type': 'application/json' });
        let options = new RequestOptions({ headers: headers });

        return this._http.post(this.loginUrl, body, options)
            .map(this.extractData)
            .catch(this.handleError);
    }

    private extractData(res: Response) {
        let body = res.json();
        return body || {};
    } 

    private handleError(error: any) {
        console.log('Yup an error occurred', error);
        return error.message || error;
    }
}

Despite implementing error handling in the login() method within user.service.ts, I seem to be stuck. Any suggestions on resolving this issue would be greatly appreciated.

Answer №1

Ensure that your handleError() function returns an Observable

If you refer to the Angular HTTP Client docs, you will find an example that can guide you in handling errors effectively.

Modify the code snippet below:

private handleError(error: any) {
    console.log('An error has occurred', error);
    return error.message || error;
}

to:

private handleError(error: any) {
    console.log('An error has occurred', error);
    return Observable.throw(error.message || error);
}

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