Course.js | A course in the most important language of right | Reactive Programming library

I can't get information from json to pug variables. The pug knows how many elements in json. but dont see title, price and etc. If i use Handlebars, not pug - code works!!! I don't understand why Handlebars works. pug not working. i trid use like this p #{price} and like this p=price. i don't know what is the problem...

index.js

My schema looks like follows:

Teacher.js

When i delete course then also delete the reference records of course.

For example i have mca course and it's reference subject is c, java, python when i delete mca also delete the all the reference subject.

How can i do this. Please help

Here is Course.js

I want to know how can I change values of combo box after every new entry in a Tkinter GUI?

SO below is the code where I am extracting values from a json file and showing it in a combo box. but I am also adding new values in the json file in the GUI but, I want to know how can I add new values to this combo box without opening the gui again in order to update the values. I want the values in combo to change immediately after a new entry is added into the json file.

I have a problem with the code - I do not understand how to solve it - I tried for a few hours - it does not work.

I do not know what's going on. I'm just trying to access from a component of courses - and a component of a single course.

I get this error:

This is the code I wrote down so far - not a long code.

course.js:

i used axios to call api methods for data access in react hooks components .i used react redux for state management. i call the fetchall method from useEffect to get all courses. but the response array is empty and show above error.there is problem with state or props like that .or the course reducer does not fetch data .here is code of api.js in action.

in my application i am reading a data from table class and i insert the id value in table test. i usually use table and insert link in jsp but this time i need to show my data by option tag and button for inserting. when i click on insert button i have this error ( threw exception [java.lang.NumberFormatException: For input string: ""] with root cause java.lang.NumberFormatException: For input string: "" )

i have no problem when i use table and link for insert so the servlet and database class working fine. i think problem can be how i am using option tag

jsp file

i am developing a servlet app that show the table in jsp and than insert a value of the that table in other table (inserting a id from table to another table) as i checked with debugger there is no problem to read a value from first table and insert it to scound table but when i clicked on insert button after some moment i have this error(java.lang.StackOverflowError) also when i check mysql table i see, i have the value more than the time that i insert it like a infinite loop.about the table that i am reading a data i can say (name of the table :class,id( type:int(primary),null:no,default:none,Extra:AUTO_INCREMENT),name(type: varchar,null:yes,default:current_timestamp)) and the table i am inserting a value is(table name test,id(type:int(index),null:yes,default:null))

i want to say it again that beside of the error i have more insertion that i click on jsp in sql table(like 100 times more)

I'm trying to use React Context to update navbar title dynamically from other child components. I created NavbarContext.js as follows. I have wrapped AdminLayout with NavContext.Provider and use useContext in Course.js to dynamically update navbar title inside useEffect. However, when I'm doing this, react throws the following error on the screen.

Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.

How can I use context properly so that I can update Header title from Course.js inside its useEffect?

NavbarContext.js