Nodejs api call from angular2 service

Question

I have node api that returns data to browser using this api :

app.get('/api/patients',function(req,res){
    Patient.getPatients(function(err,patients){
        if(err){
            throw err;
        }
        console.log(patients.length);
        res.json(patients);

    });
});

I am trying to call this api from the service class.

import { Injectable } from '@angular/core';
import { Patient } from '../patient.interface';



@Injectable()
export class PatientDataService {

    patients : Patient[] =[];


    constructor() { }



    getAllPatients(): Patient[]
    {
          // What to do here ??
    }

}

How do i return data from node api to service ?

@PankajParkar This is an Angular 2 application, not an AngularJS (1) application. — Ben
– Ben, Commented Mar 31, 2017 at 15:06
My bad.. didn't looked at Angular 2 tag.. though its would be same as http.get — Pankaj Parkar
– Pankaj Parkar, Commented Mar 31, 2017 at 15:15

Rahul Kumar · Accepted Answer · 2017-03-31 15:01:56Z

2

Use this

@Injectable()
export class PatientDataService {

    patients : Patient[] =[];


    constructor(private http:Http) { }


        getAllPatients()
         {
          return this.http.get('base_url/api/people').map((res)=>res.json());

        }

}

and in your component inject this service and call

this.patientService.getAllPatients().subscribe((data)=>{
   //data is your patient list
})

answered Mar 31, 2017 at 15:01

Rahul Kumar

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5 Comments

DevHelp Over a year ago

thank you .. this helped but now I am getting following error in browser console: XMLHttpRequest cannot load localhost:3000/api/patients. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'localhost:4200' is therefore not allowed access.

DevHelp Over a year ago

i fixed it by adding CORS in node api : app.use(function(req, res, next) { res.header("Access-Control-Allow-Origin", "*"); res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept"); next(); });

Ben Over a year ago

@DevHelp, you're making a call from an AngularJS application on one domain to your web server on another domain. Have you properly configured CORS on your web-server?

Ben Over a year ago

@DevHelp, never mind -- you beat me to it :) just be careful in any kind of production app using "*", this means any app on any domain can make a call to your web server.

DevHelp Over a year ago

Thanks Ben . How do I make sure to only allow some domains to access this service ?

Ben · Accepted Answer · 2017-03-31 15:05:33Z

2

You can first import the Angular2 Http library into your service:

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

I also import rx/js for use of Observables and mapping.

import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/map';

You can then inject the library into your service:

constructor(private _http: Http) { }

Make your http call to your node.js server like this:

getAllPatients(): Patient[]
{
      // What to do here ??
      return this._http.get('/api/patients')
           .map(this.extractData)
           .catch(this.handleError);
}

For more information, documentation, and clarification please read the Angular 2 Http Docs

answered Mar 31, 2017 at 15:05

Ben

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