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Learn how to prevent page hangs on invalid input with Express and express-validator by implementing effective validation checks and redirects.
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Solving the Hanging Page Issue in Express When Validating User Input

When working with user input in web applications, thoroughly validating data before making database requests is crucial. Express, along with the powerful express-validator library, provides an effective way to validate user inputs. However, developers sometimes encounter issues, such as a page that hangs when invalid data is submitted. In this post, we'll explore a common problem and provide a clear solution to ensure a smooth user experience.

The Problem

A user was implementing data validation in an Express application using express-validator but ran into a frustrating issue: when input data failed validation, the page would hang instead of redirecting the user. The validation checks were correctly identifying invalid data, but the current method of stopping the request was not functional and caused confusion.

The Original Code

The developer's initial code included an if condition to check for validation errors but included incorrect calls to res.end(), which resulted in the hanging page issue. Here's a simplified version of the problematic code:

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

Instead of handling the request properly, this code led to confusion and a lack of redirect functionality.

The Solution: Correctly Handling Validation Errors

To fix the hanging page issue, it was crucial to ensure that we properly handle the redirect when validation fails. The developer opted to change the approach to this problem as follows:

1. Redirect for Invalid Input

When validation errors are found, you can directly redirect the user to the intended URL without calling any end methods on the response object. Here’s the corrected part of the code:

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

By using res.redirect(), the code efficiently navigates the user to the /submitted view, ensuring they are not left with a hanging page.

2. Handling Valid Input

For valid input, you can proceed to save the applicant data as follows:

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

Full Example Code

Combining both parts, the complete code for validating and handling the POST request looks like this:

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

Conclusion

By implementing these changes, the page now behaves as expected by properly handling error validation and redirecting users as needed. Developers can ensure that their applications remain user-friendly, even when input data is invalid. Remember, effective error handling not only improves user experience but also enhances the overall quality of your application.

If you're working with user input validation in Express and face similar challenges, apply the solutions discussed in this post! You'll find that refining your code can make a significant difference.