No 'Access-Control-Allow-Origin' header in Angular 2 app

Question

For this project, I'm just learning and practicing Angular 2. I have no server-side and am making API requests to barchart ondemand api .

I'm wondering if it is possible to bypass the cors issue. I'm still fairly new to all this, so baby-step instructions are really appreciated! I'm using http://localhost:8080.

Error message: (api key commented out)

XMLHttpRequest cannot load http://marketdata.websol.barchart.com/getHistory.json?key=MY_API_KEY&symbol=GOOG&type=daily&startDate=20150311000000. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8080' is therefore not allowed access.

StockInformationService:

import {Injectable} from 'angular2/core';
import {Http, Headers} from 'angular2/http';
import {Observable} from 'rxjs/Rx';

@Injectable()
export class StockInformationService {
    private apiRoot = "http://marketdata.websol.barchart.com/getHistory.json?key=MY_API_KEY&";

    constructor (private _http: Http) {}

    getData(symbol: string): Observable<any> {
        // Tried adding headers with no luck
        const headers = new Headers();
        headers.append('Access-Control-Allow-Headers', 'Content-Type');
        headers.append('Access-Control-Allow-Methods', 'GET');
        headers.append('Access-Control-Allow-Origin', '*');

        return this._http.get(this.apiRoot + "symbol=" + symbol + "&type=daily&startDate=20150311000000", {headers: headers})
            .map(response => response.json());
    }
}

App Component:

import {Component} from "angular2/core";
import {VolumeComponent} from '../../components/volume/volume';
import {StockInformationService} from '../../core/stock-information.service';

@Component({
    selector: 'app-shell',
    template: require('./app-shell.html'),
    directives: [VolumeComponent],
    providers: [StockInformationService]
})
export class AppShell {
    constructor(private _stockInformationService: StockInformationService) {}

    // In my template, on button click, make api request
    requestData(symbol: string) {
        this._stockInformationService.getData(symbol)
            .subscribe(
                data => {
                    console.log(data)
                },
                error => console.log("Error: " + error)
            )}
    }

}

In my console, the requestData Error: Error: [object Object]

Solution 1

This a problem with the CORS configuration on the server. It is not clear what server are you using, but if you are using Node+express you can solve it with the following code

// Add headers
app.use(function (req, res, next) {

    // Website you wish to allow to connect
    res.setHeader('Access-Control-Allow-Origin', 'http://localhost:8888');

    // Request methods you wish to allow
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');

    // Request headers you wish to allow
    res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');

    // Set to true if you need the website to include cookies in the requests sent
    // to the API (e.g. in case you use sessions)
    res.setHeader('Access-Control-Allow-Credentials', true);

    // Pass to next layer of middleware
    next();
});

that code was an answer of @jvandemo to a very similar question.

Solution 2

You can read more about that from here: http://www.html5rocks.com/en/tutorials/cors/.

Your resource methods won't get hit, so their headers will never get set. The reason is that there is what's called a preflight request before the actual request, which is an OPTIONS request. So the error comes from the fact that the preflight request doesn't produce the necessary headers. check that you will need to add following in your .htaccess file:

Header set Access-Control-Allow-Origin "*"

Solution 3

I have spent lot of time for solution and got it worked finally by making changes in the server side.Check the website https://docs.microsoft.com/en-us/aspnet/core/security/cors

It worked for me when I enabled corse in the server side.We were using Asp.Net core in API and the below code worked

1) Added Addcors in ConfigureServices of Startup.cs

public void ConfigureServices(IServiceCollection services)
    {
        services.AddCors();
        services.AddMvc();
    }

2) Added UseCors in Configure method as below:

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseCors(builder =>builder.AllowAnyOrigin());
        app.UseMvc();
    }

Solution 4

I also had the same issue while using http://www.mocky.io/ what i did is to add in mock.io response header: Access-Control-Allow-Origin *

To add it there just need to click on advanced options

Once this is done, my application was able to retrieve the data from external domain.

Solution 5

Simply you can set in php file as

header("Access-Control-Allow-Origin: *");
header("Content-Type: application/json; charset=UTF-8");

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