Angularjs consume Restful in different domains

Question

Good afternoon, I am trying to make a client that indexes the information of various webservices (on bitcoin quotes from various brokers) but when trying to access the webservice the values imported from json are not displayed, and pressing F12 on Chrome returns the following error message:

Xmlhttprequest cannot load https://api.blinktrade.com/api/v1/BRL/ticker?crypto_currency=BTC. No 'Access-Control-Allow-Origin' header is present on the requested Resource. Origin 'http://localhost' is therefore not allowed access.

have already given a search on the error, the same tbm occurs on my remote test server (Hostinger), I know the error occurs because the server does not return the header "Access-Control-Allow-Origin = *" however are many different third party servers that I will fetch and all return me this same error...

follows the code used to access WS: (service)

app.factory('foxbit', ['$http', 
function($http){	
	return $http.get('https://api.blinktrade.com/api/v1/BRL/ticker?crypto_currency=BTC')
	.success(function(data) {
	  return data;
	})
	.error(function(err) {
	  return err;
	});
}]);

Controller:

app.controller('MainController', ['$scope', 'foxbit', function($scope, foxbit) {
  foxbit.success(function(data) {
    $scope.cotacaofox = data;
  });
  
}]);

So if the ninjas here can point me to a way around this mistake,.

Thank you.

Answer 1

This is a limitation imposed by CORS. Two possibilities:

• Ask the blinktrade.com service maintainers to include their source domain in the list of authorized domains, or
• Implement a local proxy service, eliminating CORS evaluation.

An example of proxy in C#/Webapi 2 comes next:

[RoutePrefix("stack/proxy")]
public class ProxyController : ApiController
{
    [Route("")]
    [HttpGet]
    public object Search([FromUri] string url)
    {
        try
        {
            var client = new HttpClient();
            var result = client.GetStringAsync(url).Result;

            var resp = new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StringContent(result, System.Text.Encoding.UTF8, "text/plain")
            };

            return resp;
        }
        catch (Exception e)
        {
            throw;
        }
    }
}

Use:

http://localhost:49801/stack/proxy/? url=https://api.blinktrade.com/api/v1/BRL/ticker?crypto_currency=BTC

Upshot:

{
"high":1693.88,
"vol":248.24057349,
"buy":1623.55,
"last":1623.54,
"low":1551.01,
"pair":"BTCBRL",
"sell":1625.11,
"vol_brl":403631.3524226
}

Webapi controller source code taken from Nyan project (github).