Opening and reading a file with askopenfilename in Tkinter?

When a user wants to open a file from a directory, the preferred way to do this is to display a popup where the user selects a file to open. Like most tools and widgets, Tkinter provides us a way to open a dialog for opening a file, reading a file, saving a file. All these functionalities are part of filedialog module in Python. Just like other widgets, filedialog needs to be imported explicitly in the notebook. There are certain other modules that contain the filedialog such as askdirectory, askopenfilename, askopenfile, askopenfilenames, asksaveasfilename, etc.

Syntax

The askopenfilename() function opens a file dialog and returns the path of the selected file ?

filedialog.askopenfilename(
    title="Select a file",
    initialdir="/",
    filetypes=[("Text files", "*.txt"), ("All files", "*.*")]
)

Parameters

• title − The title displayed on the file dialog window
• initialdir − The initial directory to open
• filetypes − A list of tuples specifying file types and extensions

Example

In this example, we will define a function to open and read a file using askopenfilename. We will create an application which contains a button to open a file and will display the content of the file in a Label widget ?

# Import tkinter library
from tkinter import *
from tkinter import ttk
from tkinter import filedialog

# Create an instance of tkinter frame or window
win = Tk()
win.geometry("750x150")
win.title("File Reader")

# Define a function to open the specific file using filedialog
def open_files():
    path = filedialog.askopenfilename(
        title="Select a file", 
        filetypes=[("text files", "*.txt"), ("all files", "*.*")]
    )
    
    if path:  # Check if a file was selected
        try:
            file = open(path, 'r')
            txt = file.read()
            label.config(text=txt, font=('Courier', 10, 'normal'))
            file.close()
            button.config(state=DISABLED)
            win.geometry("750x450")
        except Exception as e:
            label.config(text=f"Error reading file: {str(e)}")

# Create an empty Label to read the content of the file
label = Label(win, text="", font=('Courier', 13, 'bold'), wraplength=700, justify=LEFT)
label.pack(padx=10, pady=10)

# Create a button for opening files
button = ttk.Button(win, text="Open", command=open_files)
button.pack(pady=30)

win.mainloop()

How It Works

The program creates a simple GUI with a button that opens a file dialog when clicked. The askopenfilename() function displays a file browser dialog where users can select text files or any file type. Once a file is selected, the program reads its contents and displays them in a label widget.

Key Features

• File Type Filtering − The dialog filters files by type (text files, all files)
• Error Handling − Checks if a file was selected and handles read errors
• Dynamic Resizing − The window expands to accommodate file content
• Button State Management − The Open button is disabled after successful file loading

Common Use Cases

• Text file viewers and editors
• Configuration file loaders
• Data import applications
• Log file analyzers

Conclusion

The askopenfilename() function provides an easy way to implement file selection dialogs in Tkinter applications. It returns the selected file path, which can then be used to read and process file contents in your Python programs.