update

pbl.js

@@ -3181,7 +3181,7 @@ router.route("/addClassStudent").all((req, res, next) => {
         _userdata.unshift(_mysqlLabor[0], _mysqlLabor[1], "selectUser");
         mysql.usselect(_userdata, function(ret) {
             let classid = ret[0][0].classid;
-            if (classid.indexOf(cid) == -1) {
+            if (!classid || classid.indexOf(cid) == -1) {
                 classid = classid ? classid.split(",") : []; 
                 classid.push(cid);
                 let _userdata2 = [student[i], classid.join(",")];
@@ -3208,7 +3208,7 @@ router.route("/addClassTeacher").all((req, res, next) => {
       _userdata.unshift(_mysqlLabor[0], _mysqlLabor[1], "selectUser");
       mysql.usselect(_userdata, function(ret) {
           let classid = ret[0][0].cclassid;
-          if (classid.indexOf(cid) == -1) {
+          if (!classid || classid.indexOf(cid) == -1) {
               classid = classid ? classid.split(",") : []; 
               classid.push(cid);
               let _userdata2 = [student[i], classid.join(",")];