如何将动态值传递给angularjs中的$ http.post

Here is the scenario, I have a "Get course" button in the page when i click of the button, i'm passing courseId, In getCourse() method am returning $scope.courseId; then i'm passing this variable in $http.post method. but when i debug in developer tool i'm not getting courseId value. Here is the scenario, I have a "Get course" but