Скачать или смотреть How to Retrieve and Save Dropdown Values in a Tkinter App using OptionMenu Widgets

Discover how to effectively gather the selected values from `OptionMenu` widgets in a Tkinter application and save them into a JSON file.
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This video is based on the question https://stackoverflow.com/q/71634180/ asked by the user 'vivekveeramani' ( https://stackoverflow.com/u/2738809/ ) and on the answer https://stackoverflow.com/a/71641192/ provided by the user 'Derek' ( https://stackoverflow.com/u/15518276/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Mastering Tkinter: How to Retrieve and Save Values from Multiple OptionMenu Widgets

Creating a user-friendly application can sometimes pose challenges, especially when dealing with graphical user interfaces (GUIs) like those in Tkinter. One common problem developers face is how to efficiently retrieve the values from multiple dropdown menus, specifically OptionMenu widgets, and save them for further processing. In this post, we’ll explore a clear and organized solution to extract dropdown selections in a Tkinter application, particularly useful in cases like tagging images.

The Background: Understanding the Problem

In our scenario, we are developing a minimalist image tagging app. The goal is to list various images alongside dropdown menus, allowing users to tag each image with specific labels. Once tagging is complete, the next step involves saving these selections into a JSON file for storage and future use.

Current Code Structure

Our code already has the basic setup for displaying the images and their corresponding dropdowns. Here’s a summarized outline of the classes and methods we are working with:

Class App: The main application class containing all functionalities.

GetRows Method: Responsible for creating the list of images and corresponding OptionMenu widgets.

SaveState Method: Intended for saving the selections but is currently unimplemented.

What We Need to Do

Before we can save the data, we need to ensure that we can access the values of each OptionMenu. The current implementation of GetRows does not allow us to retrieve these values. Here’s how we can successfully address this issue.

The Solution: Accessing and Saving Dropdown Values

The solution revolves around modifying the setup of your StringVar instances and properly storing their references for later use when saving selections.

Step 1: Store References to StringVar Instances

First, we need to make sure we can access the StringVar instances outside of the GetRows method. Here’s how:

Initialize a list to store the references to the StringVar instances.

Append each StringVar to this list as we create them.

Updated Code Snippet

We can modify the GetRows method as follows:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Implement the SaveState Method

Next, we’ll implement the SaveState method to retrieve the selected values and save them into a JSON file. Here’s how we can accomplish this:

Create a dictionary to hold our data.

Loop through the list of StringVar references and fetch their values.

Use the json module to write this data to a JSON file.

Sample Implementation of SaveState

[[See Video to Reveal this Text or Code Snippet]]

Conclusion: Bringing It All Together

With these modifications, your application will now be able to collect the selected values from all OptionMenu widgets within the Tkinter frame and save them to a JSON file—a crucial step in your image tagging process.

By understanding and applying this structured approach, you can effectively manage multiple dropdown selections and enhance the functionality of your Tkinter applications. Happy coding!