Скачать или смотреть Displaying Selected Items from a DropdownList in ASP.NET with Ease

Learn how to instantly show the selected item from a `DropdownList` in your ASP.NET applications using simple steps.
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This video is based on the question https://stackoverflow.com/q/62634996/ asked by the user 'Aycan Candar' ( https://stackoverflow.com/u/11649724/ ) and on the answer https://stackoverflow.com/a/62636511/ provided by the user 'Allen Kuo' ( https://stackoverflow.com/u/11082298/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Display Selected Items from a DropdownList in ASP.NET

When developing web applications using ASP.NET, one common requirement is to display the selected item from a DropdownList instantly when a user makes a choice. If you've been struggling with this functionality, you're not alone! This guide will walk you through a simple and effective solution to achieve this.

Understanding the Problem

Suppose you have a DropdownList (or a combo box) with several options, and you want to display the currently selected item on a label right away. This offers a better user experience as the changes appear immediately with their selections. Many developers can get confused between using a combo box and a dropdown list, especially when implementing event handlers. In this guide, we’ll focus on how to make this happen using ASP.NET.

The Solution: Step-by-Step

To implement this functionality, follow these steps:

1. Setup the ASP.NET Markup

The first part of the solution is to set up your ASP.NET page (e.g., Default.aspx) with the necessary controls:

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2. Bind Data to the Dropdown List

Next, you’ll want to bind data to the dropdown list upon loading the page. Open the code-behind file (e.g., Default.aspx.cs) and write the following code inside the Page_Load method:

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Explanation: The !IsPostBack check ensures that the dropdown list is populated only when the page is loaded for the first time, preventing it from being repopulated on subsequent postbacks.

3. Handle the SelectedIndexChanged Event

Now, you need to handle the event when a user changes their selection in the dropdown list. Below is the method to do that:

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Explanation: This method will update the text of the label (lbl1) to reflect the currently selected item from the dropdown list whenever a selection change occurs.

Result: Instantly Display the Selection

With this setup, when a user selects an item from the dropdown list, the corresponding label will update instantly to reflect this choice. This not only enhances your application's interactivity but also improves the overall user experience.

Conclusion

Implementing a DropdownList in ASP.NET to display selected items on a label is straightforward when following these clear steps. By utilizing the AutoPostBack feature and handling the SelectedIndexChanged event appropriately, you can create a responsive user interface that immediately reflects user selections.

Now that you have a solid understanding of how to make selections appear on a label instantly, you're ready to enhance your ASP.NET applications with ease!

If you have further questions or run into any challenges while implementing this, feel free to reach out. Happy coding!