Tkinter按钮不从函数返回值

Question

I am currently trying to create a small UI for a function that returns some value from a data frame based on the string that has been entered. The string is split and each individual substring is looked up in my data frame using iloc. The issue is, when calling this function using a button in Tkinter, nothing is being returned. It works fine without Tkinter so I am unsure where the error is occurring.

master = Tk()
e1 = Entry(master)

list_of_inputs = e1.get().split()

def show_entry_fields():
    i=0
    while (i<len(list_of_inputs)):
        return (backend.loc[backend['Keyword'] == list_of_inputs[i]]) 
        i=i+1

Label(master, text="Enter Title").grid(row=0)

e1.grid(row=0, column=1)

Button(master, text='Show', command=show_entry_fields).grid(row=0, column=2, sticky=W, pady=4)

mainloop( )

Answer 1

Couple of things:

• You are checking the value of your Entry before the user has a chance to fill it in. You should get the user input only when the button is pressed.
• Your while loop in the show_entry_fields() function will always run once regardless of how many inputs provided, since you put a return statement inside the loop
• Your handler function has to modify an existing data structure or graphical component, if you return your result you cant collect it

Possible implementation:

master = Tk()
e1 = Entry(master)


def show_entry_fields():
    list_of_inputs = e1.get().split()
    result = []
    for entry in list_of_inputs:
        result.append(backend.loc[backend['Keyword']] == entry)
    # Alternatively, you can create the list with
    # result = [backend.loc[backend['Keyword']] == entry for entry in list_of_inputs]
    # Here, deal with the result    

Label(master, text="Enter Title").grid(row=0)
e1.grid(row=0, column=1)
Button(master, text='Show', command=show_entry_fields).grid(row=0, column=2, sticky=W, pady=4)
mainloop()