Python loop dictionary items through a tkinter GUI using a button

Question

I am currently making a menu test for my restaurant. I have made the GUI and am happy with its basic format (for now), but I am stuck on how to do my next step.

I have multiple checkboxes set up (different ingredients) and the plan is for different menu items to loop through (appear on the screen), the employee then checks the appropriate ingredients, clicks a submit and continue button that I have made and then the next menu item shows up in place of the previous one. There will be much more I have to do like reading and storing the input but for now I wanted to leap this hurdle before I moved on.

I am new with using Python for GUIs so I am not sure the best way to go about doing this.

I have found different code examples but nothing specific enough to implement into my program. Any advice is much appreciated!!

Here is a pic of my GUI:

from tkinter import *

globalvar = -1

class Example(Frame):

    def __init__(self, parent):
        Frame.__init__(self, parent, background="white")   
        self.parent = parent
        self.initUI()

    def initUI(self):
        self.parent.title("Wahoos Menu Test")

def main():
    def callBack(number):
        globalvar = number + 1
        item(globalvar)
    def item(number):
        menu = ['nft', 'nckt']
        m = Label(root, text=menu[number], fg="orange").grid(row=7, column=0)
    root = Tk()
    app = Example(root)
    #root.geometry("750x750+400+50")
    for r in range(20):
        for c in range(14):
            Label(root, text='',
                borderwidth=0).grid(row=r,column=c)

    B = Button(root, text ="Submit and Continue", relief=RIDGE, fg="black", command= lambda:callBack(globalvar)).grid(row=19, column=7)
    L = Label(root, text="What comes in the following", fg="blue").grid(row=6, column=0)
    #I = Label(root, text="***Loop Items Here***", fg="blue").grid(row=7, column=0)
    V = Label(root, text="Veggies", fg="green").grid(row=1, column=11, sticky=W)
    v1 = IntVar()
    Checkbutton(root, text="Lettuce", variable=v1, fg="black").grid(row=2, column=11, sticky=W)
    v2 = IntVar()
    Checkbutton(root, text="Cabbage", variable=v2).grid(row=3, column=11, sticky=W)
    v3 = IntVar()
    Checkbutton(root, text="Cheese", variable=v3).grid(row=4, column=11, sticky=W)
    v4 = IntVar()
    Checkbutton(root, text="Ahee Rice", variable=v4).grid(row=5, column=11, sticky=W)
    v5 = IntVar()
    Checkbutton(root, text="Brown Rice", variable=v5).grid(row=6, column=11, sticky=W)
    v6 = IntVar()
    Checkbutton(root, text="Banzai Veg", variable=v6).grid(row=7, column=11, sticky=W)
    v7 = IntVar()
    Checkbutton(root, text="Red Cabbage", variable=v7).grid(row=8, column=11, sticky=W)
    v8 = IntVar()
    Checkbutton(root, text="Black Beans", variable=v8).grid(row=9, column=11, sticky=W)
    v9 = IntVar()
    Checkbutton(root, text="Cajun White Beans", variable=v9).grid(row=10, column=11, sticky=W)
    T = Label(root, text="Tortillas     ", fg="green").grid(row=1, column=12, sticky=W)
    t1 = IntVar()
    Checkbutton(root, text="Corn          ", variable=t1).grid(row=2, column=12, sticky=W)
    t2 = IntVar()
    Checkbutton(root, text="Flour", variable=t2).grid(row=3, column=12, sticky=W)
    P = Label(root, text="Proteins", fg="green").grid(row=1, column=13, sticky=W)
    p1 = IntVar()
    Checkbutton(root, text="Carne Asada", variable=p1).grid(row=2, column=13, sticky=W)
    p2 = IntVar()
    Checkbutton(root, text="Flamebroiled Chicken", variable=p2).grid(row=3, column=13, sticky=W)
    p3 = IntVar()
    Checkbutton(root, text="Blackened Chicken", variable=p3).grid(row=4, column=13, sticky=W)
    p4 = IntVar()
    Checkbutton(root, text="Flamebroiled Fish", variable=p4).grid(row=5, column=13, sticky=W)
    p5 = IntVar()
    Checkbutton(root, text="Pork", variable=p5).grid(row=6, column=13, sticky=W)
    p6 = IntVar()
    Checkbutton(root, text="Shrimp", variable=p6).grid(row=7, column=13, sticky=W)
    p7 = IntVar()
    Checkbutton(root, text="Tofu", variable=p7).grid(row=8, column=13, sticky=W)
    p8 = IntVar()
    Checkbutton(root, text="Blackened Mushroom", variable=p8).grid(row=9, column=13, sticky=W)
    p9 = IntVar()
    Checkbutton(root, text="Rice and Beans", variable=p9).grid(row=10, column=13, sticky=W)
    p10 = IntVar()
    Checkbutton(root, text="Banzai Veg", variable=p10).grid(row=11, column=13, sticky=W)
    S = Label(root, text="Sauces", fg="green").grid(row=1, column=14, sticky=W)
    s1 = IntVar()
    Checkbutton(root, text="Salsa", variable=s1).grid(row=2, column=14, sticky=W)
    s2 = IntVar()
    Checkbutton(root, text="Guacamole", variable=s2).grid(row=3, column=14, sticky=W)
    s3 = IntVar()
    Checkbutton(root, text="Sour Cream", variable=s3).grid(row=4, column=14, sticky=W)
    s4 = IntVar()
    Checkbutton(root, text="Roasted Pepper", variable=s4).grid(row=5, column=14, sticky=W)
    s5 = IntVar()
    Checkbutton(root, text="Ketchup", variable=s5).grid(row=6, column=14, sticky=W)
    s6 = IntVar()
    Checkbutton(root, text="Ranch", variable=s6).grid(row=7, column=14, sticky=W)
    s7 = IntVar()
    Checkbutton(root, text="Balsamic", variable=s7).grid(row=8, column=14, sticky=W)
    s8 = IntVar()
    Checkbutton(root, text="Mr. Lees", variable=s8).grid(row=9, column=14, sticky=W)
    s9 = IntVar()
    Checkbutton(root, text="Teriyaki", variable=s9).grid(row=10, column=14, sticky=W)
    s10 = IntVar()
    Checkbutton(root, text="Tapatio", variable=s10).grid(row=11, column=14, sticky=W)
    s11 = IntVar()
    Checkbutton(root, text="Cream Cheese", variable=s11).grid(row=12, column=14, sticky=W)
    s12 = IntVar()
    Checkbutton(root, text="Aoli", variable=s12).grid(row=13, column=14, sticky=W)

    root.bind('<Return>', callBack)
    root.mainloop()  


if __name__ == '__main__':
    main() 

Answer 1

In your callBack method, globalvar = number + 1 does not update the value of the global variable globalvar, it creates a new local variable called globalvar. If you want the globalvar variable to be altered, you have to add global globalvar in your method to explicitly refer to your global variable.

def callBack(number):
    global globalvar
    globalvar = number + 1
    item(globalvar)

Note that using such a global variable, you do not need to have the value passed as a parameter and could just use Button(...,command=callBack)

Other remarks:

• with the grid geometry manager, you do not have to create the 20x14 "empty label" table (removing this loop will not change anything)
• in item method, instead of creating a Label, you could update the text of the existing one (it implies (1) holding a reference to the label in a variable (2) call config(text="new text") on this reference). Creating new labels will reveal hazardous when replacing a label by a shorter (you are now just stacking them on top of others)
• when you initialize B, L, I, V, you do not store anything in the variable. You store the answer of the call to grid (which is always None). To keep a reference on items you have to split your code in two lines :

L = Label(root, text="What comes in the following", fg="blue")
L.grid(row=6, column=0)