在 <string> &#39;需要将字符串作为左操作数，而不是StringVar

Question

I'm trying to use the self.search to determine which lines from my .txt file will be diplayed, ie: entry is "Blue" and it will print all lines with Blue in the text.
Each button searches a different .txt file.

Exception in Tkinter callback Traceback (most recent call last): File "C:\\Users\\gblmac\\AppData\\Local\\Programs\\Python\\Python36-32\\lib\\tkinter__init__.py", line 1702, in call return self.func(*args) File "D:\\Users\\gblmac\\Desktop\\Python programs\\Testing\\GUI class and init .py", line 37, in searchvision if self.usertext in line: TypeError: 'in ' requires string as left operand, not StringVar

from tkinter import *

class App:
    def __init__(self):
        self.master = Tk()
        self.master.title("PM and Vision Finder")
        self.master.configure(bg="orange")
        self.master.geometry("500x500")
        self.mybutton1 = Button(self.master, text="Vision Names", command=self.searchvision)

        self.mybutton1.grid(row=0, column=0)

        self.mybutton2 = Button(self.master, text="PM",
                           command=self.searchpm)

        self.mybutton2.grid(row=1, column=0)

        self.usertext = StringVar()
        self.initialtext = StringVar()
        self.initialtext.set ("Type Here")

        self.myentry = Entry(self.master, textvariable=self.initialtext)
        self.myentry.grid(row=2, column=0)

    def searchvision(self):

        self.search = open(r"D:\Users\gblmac\Desktop\Python programs\Vision Names\Vision Names.txt")
        for line in self.search:
            if self.usertext in line:
                print (line)

    def searchpm(self):

        self.search = open(r"D:\Users\gblmac\Desktop\Python programs\PMs\PMs.txt")
        for line in self.search:
            if self.usertext in line:
                print (line)

        print (self.usertext.get())


    self.master.mainloop()

App()

Answer 1

in requires string as left operand

For this

if self.usertext in line:

not StringVar

Because the left side variable is a StringVar

self.usertext = StringVar()

You need to use

if self.usertext.get() in line: