处理角度2中http.get的成功和错误响应

Question

I am using foursquare api to grab longitude and latitude coordinates for searched venue, function looks like this:

getCoordinates(params) {
   this.http.get(URL+params)
    .map(res => res.json())
    .subscribe(
      data => this.coordinates = data,
      err => this.logError(err)
    );
   // return coordinates;
  }

I am trying to figure out how to perform specific tasks in case of success or error, so if it is a success case I want to return coordinates if not print an error to the console, but not return coordinates . I think I more or less got the error bit down, but can't figure success action (commented it out at the moment as it is called in success and error cases)

EDIT: seeing how this question can pop up in the future, what would be logic to check for success or failure of a http.post ?

Answer 1

In fact the subscribe method allows to register callbacks for success and factures. Perhaps arrow functions disturb you a bit:

this.http.get(...)
  .map(res => res.json())
  .subscribe(
    data => {
      // Processing for successfull response
    },
    error => {
      // Processing for failures
    }
  );

You can only return the observable (for example from a service) but not a result because HTTP requests are asynchronous. Then you can subscribe on it within components for example and set component attributes to be displayed in the view.

Hope it helps you. Thierry

Answer 2

you can chain the http.get() with a then function, where you can put the success and error callbacks:

this.http.get(URL+params).then(function(data){
    // success
}, function(data){
    // error
});