Tkinter object scope

[deanhystad]

This is easy to figure out if you let Python help.

First you look at the error message:

Error:
    book = Book(self.entBookTitle.get(), self.entBookISBN.get(), self.entBookAuthor.get(), self.entBookYear.get())
                ^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'get'

The next thing I would do is put a breakpoint on line 32 and run the program in the debugger, or add a print command before line 32 to display the value of self.entBookTitle.

    def SaveBook(self):
        print(self.entBookTitle)
        book = Book(self.entBookTitle.get(), self.entBookISBN.get(), self.entBookAuthor.get(), self.entBookYear.get())

This would verify that self.entBookTitle is indeed None.

Next search for every line that includes entBookTitle and focus on lines that assign a value to entBookTitle. In your posted code this only happens on line 17.

        self.entBookTitle = ttk.Entry(frameRight, font=('Helvetica', 12), width=20).pack(padx=10, pady=10)

Using the debugger I would set a breakpoint on line 18, or add a print statement right after line 17 to see the value of self.entBookTitle right after the assignment. The value would indeed be Null. Now you have isolated the problem to 1 line which contains an assignment and two function calls. These are the two function calls:

ttk.Entry(frameRight, font=('Helvetica', 12), width=20)
.pack(padx=10, pady=10)

One of these returns None. I would rewrite like this:

        self.entBookTitle
temp = ttk.Entry(frameRight, font=('Helvetica', 12), width=20)
print("entry", temp)
temp.pack(padx=10, pady=10)
print("pack", temp)
self.entBookTitle = temp

Run the code and you would see that "ttk.Entry(frameRight, font=('Helvetica', 12), width=20)" returns a ttkEntry object and pack() returns None. Armed with that information you would quickly realize that you need to break up creating and packing the entry widget.

self.entBookTitle = ttk.Entry(frameRight, font=('Helvetica', 12), width=20)
self.entBooktitle.pack(padx=10, pady=10)

I'm confident that you would have solved this problem quite quickly if you did a little poking around instead of immediately throwing up your hands in frustration. Give yourself some credit.