How to make POST request to external API using Angular2?

Question

I'm trying to leverage CORS to make a post request. I came across several articles/answers related to CORS but somehow just couldn't get it working.

As I understand, the access-control-allow-origin: * is to be set on the server side to get this working but what I have here is a angular-cli project.

My project is purely Angular 2.1 based and no backend server is involved. Any suggestions as to how to set it up properly will be highly appreciated.

The exact error that I'm getting is this:

"NetworkError: 404 Not Found - https://flowxo.com/hooks/a/rbpja7r2/?usertype=User"

and this warning in console:

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the
remote resource at https://flowxo.com/hooks/a/rbpja7r2/?usertype=User.
(Reason: CORS header 'Access-Control-Allow-Origin' missing).

Update:

Here's how I'm trying to make a POST request:

let headers = new Headers();
headers.append('Access-Control-Allow-Headers', 'Content-Type');
headers.append('Content-Type', 'application/json');
headers.append('Access-Control-Allow-Methods', 'POST, OPTIONS');
headers.append('Access-Control-Allow-Origin', '*');
return this.http.post(
    this.flowxoUrl,
    JSON.stringify(formData),
    {headers: headers}
  )
  .map((res:Response) => res.json())
  .catch((error:any) => Observable.throw(error.json().error || 'Server error')); //...errors if any

Answer 1

This is server side issue, not Angular.

Your server should respond with Access-Control-Allow-Origin header.

Java (Spring) example:

@Component
@Order(Ordered.HIGHEST_PRECEDENCE)
public class SimpleCorsFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {}

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        response.setHeader("Access-Control-Allow-Origin", "*"); //you can specify domains here * - is a wildcard, it will allow all origins to request
        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE, PUT");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Headers", "x-requested-with, authorization, content-type");

        if("OPTIONS".equalsIgnoreCase(request.getMethod())) {
            response.setStatus(HttpServletResponse.SC_OK);
        } else {
            filterChain.doFilter(servletRequest, servletResponse);
        }
    }

    @Override
    public void destroy() {}
}