调整

public/react/src/modules/courses/coursesDetail/CoursesLeftNav.js

@@ -682,20 +682,24 @@ class Coursesleftnav extends Component{
 
 		if(result.source.droppableId==="shixun_homework"||result.source.droppableId==="graduation"||result.source.droppableId==="attachment"){
 
-     let url ="/course_second_categories/"+result.draggableId+"/move_category.json"
+			let url ="/course_second_categories/"+result.draggableId+"/move_category.json";
+			if(result.destination.index!=null){
 				this.droppablepost(url,result.destination.index+1)
-
+			}
 		}else if(result.source.droppableId==="board"){
 
-     let url ="/boards/"+result.draggableId+"/move_category.json"
+			let url ="/boards/"+result.draggableId+"/move_category.json";
+			if(result.destination.index!=null) {
 				this.droppablepost(url, result.destination.index + 1)
-
+			}
 		}else if(result.source.droppableId==="course_group"){
 			if(result.draggableId!=1){
-				let url ="/course_groups/"+result.draggableId+"/move_category.json"
+				let url ="/course_groups/"+result.draggableId+"/move_category.json";
+				if(result.destination.index!=null) {
 					this.droppablepost(url, result.destination.index + 1)
 				}
 			}
+		}
 
   }