Angular2 http.post gets executed twice

Question

I came across a weird issue where the Angular2\'s (RC1) Http service executes the http.post call twice. I\'ve debugged my app and I know for a fact this is not a click event

Answer 1

its happening because HTTP OPTIONS executed first, and you have to restrict unwanted HTTP method before executing your Logic, always use isset method,see example below

 if(isset($_POST))
 {
    $name = $_POST["name"];
    $country = $_POST["country"];

    $sql = 'INSERT INTO user values("' . $name . '","' . $country . '")';

            if ( $conn->query($sql)=== TRUE) 
            {
                $outp =  "Inserted " .  $name . "  and  "  . $country;
                echo json_encode($outp);
            } else {
                echo json_encode("Error: " . $sql . "<br>" . $conn->error);
            }
        }


here it will insert row in table only when its POST METHOD.

Answer 2

This was happening to me because I have (key.enter)="someSubmitFunction()" on one of the input fields of a form. When I hit enter on this field the form would submit twice. Apparently, this wasn't needed. When I removed this, the form would still submit when I hit enter, but now only once.

Answer 3

The http service returns a cold observable that get executed on every subscribe, you want to convert it to a hot observable that get only executed on the first subscribe and share the same value for subsequent subscribes.

To convert it all you have to do is share it:

return this._http.post(this.createURL(this.getCreateURL(), [], params), body, options)
.map(res => this.handleObjectResponse(res))
.share();