发送课程的时候提示语修改

public/javascripts/wechat/controllers/send_class_list.js

@@ -30,6 +30,11 @@ app.controller('SendClassListController', ['$scope', '$http','$routeParams', 'co
             }
         }
 
+        if(course_ids.length <= 0){
+            vm.alertService.showMessage('提醒', '请先选择班级');
+            return;
+        }
+        
         $http.post(config.apiUrl + "resources/send", {
             token: auth.token(), course_ids: course_ids, send_id: send_id
         }).then(function(response){