Solving the Dropdown Selection Issue in ASP.NET MVC 5 with jQuery and AJAX

Описание: Learn how to dynamically populate multiple textboxes from a dropdown selection in ASP.NET MVC 5 using jQuery and AJAX effectively.
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This video is based on the question https://stackoverflow.com/q/63733558/ asked by the user 'mohamed' ( https://stackoverflow.com/u/14110058/ ) and on the answer https://stackoverflow.com/a/63735598/ provided by the user 'Li-Jyu Gao' ( https://stackoverflow.com/u/8673618/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Solving the Dropdown Selection Issue in ASP.NET MVC 5 with jQuery and AJAX

When developing web applications, it's common to encounter situations where user inputs from dropdown menus need to dynamically affect other components on the page. One such issue arises when a dropdown selection only populates a single textbox, leaving others unfilled. In this post, we will troubleshoot and fix this common problem when using ASP.NET MVC 5, jQuery, and AJAX.

Understanding the Problem

In our scenario, we have a dropdown that is populated from a database, but when a selection is made, only one textbox reflects the change. This can lead to user confusion as they expect all relevant textboxes to update based on the dropdown selection. Here’s a brief overview of the symptoms:

Multiple textboxes are present, but only one updates based on dropdown changes.

The dropdown is populated using AJAX, potentially affecting the update due to improper function implementation.

Breaking Down the Solution

To resolve this issue, we need to focus on the JavaScript function responsible for updating the textboxes. The original code defines multiple functions with the same name, which is likely causing one to overwrite the other due to a JavaScript behavior known as hoisting. This leads to only the last function being executed, reflecting only one textbox's update.

Step 1: Consolidate the Function

Instead of having three separate getValue() functions, we can create a single function that updates all required textboxes. Here’s how to do it:

Revised JavaScript Function

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

Step 2: Update the AJAX Call

Make sure that your AJAX call initializes the dropdown list correctly and that the onchange event correctly triggers the new consolidated function.

Step 3: Complete Code Example

Putting it all together, your complete code would look like the following:

Dropdown in Razor View:

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

Textboxes in Razor View:

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

AJAX initialization:

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

Conclusion

By consolidating your functions into a single one and ensuring that your AJAX call is properly set up to populate the dropdown, you can ensure that all textboxes update as expected on selection changes. This technique not only improves code maintainability but also enhances user experience by providing consistent and predictable behavior in your web application.

Now, your dropdown should work seamlessly with multiple textboxes in ASP.NET MVC 5 using jQuery and AJAX. If you have any further questions or run into additional issues, feel free to leave a comment!