Resolving Formik setFormValues Not Working Inside useEffect

Discover how to resolve the issue of Formik’s `setFormValues` not updating as expected inside a `useEffect`, ensuring proper formatting and functionality for your masked input.
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Troubleshooting Formik's setFormValues Issue Inside useEffect

When working with React and Formik, developers often encounter unexpected behaviors, especially when integrating libraries like react-text-mask for masked inputs. One common issue arises when attempting to update form values using setFormValues inside a useEffect. This guide will break down this problem and provide clear, actionable solutions to achieve your desired results.

The Problem

Imagine you have a form that includes a masked input for phone numbers. You set some initial values, and after an interval, you want to dynamically update the input with new values. However, you notice that calling setFormValues() inside useEffect doesn’t seem to work as expected. The initial value doesn’t change, and the masked input doesn't reflect the new value.

Code Example

Here’s the relevant snippet of the code that demonstrates the issue:

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

The goal is to see the masked input populated with the new phone number [phone] after one second, but the initial value persists.

The Solution

Step 1: Adjust Initial Values

The first step to resolving the issue is to modify the initial values of Formik. Instead of hardcoding these values, utilize the state variable formValues. Here’s how to make the change:

Replace this line:

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

With this line:

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

This modification ensures that the form will utilize the updated formValues state, allowing it to react to changes made via setFormValues().

Step 2: Update Package Version

Change from:

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

To:

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

This downgrade prevents the masking issues encountered in later versions, ensuring that the mask applied to your input consistently functions as desired.

Additional Note

It's worth mentioning that the react-text-mask library has not been actively maintained since July 2018. Be cautious when using such libraries in production, as they may lead to further discrepancies with future React updates.

Conclusion

By following these steps, you'll effectively resolve the issue of Formik setFormValues not functioning inside a useEffect. With proper adjustments to both the Formik configuration and dependencies, your masked input can dynamically reflect changes as intended. Now, the input should show the new number [phone] after the timeout period, finally achieving both your goals.

Feel free to reach out in the comments if you encounter any further issues or have additional questions about React, Formik, or masked inputs!