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Learn how to leverage Formik with Yup in React to validate text inputs dynamically based on the selected country.
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How to Use Yup to Validate Text Input Based on Selected Country in Formik?

Handling form validation efficiently in React can be challenging, but Formik and Yup make the task significantly easier. In this post, we'll explore how to validate text input based on the selected country by utilizing Formik with Yup.

Introduction to Formik and Yup
Formik is a powerful library that helps manage form state in React applications, while Yup is a JavaScript schema builder for value parsing and validation. Together, they offer a cohesive solution for handling complex form validation scenarios.

Setting Up the Form
First, install Formik and Yup in your project:

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

In your React component, create a form using Formik:

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

Explanation
In this example, we have a form with two fields: country and postal code. We use Yup to create a validation schema that changes dynamically based on the selected country. The countrySchemas object defines regular expressions for validating postal codes from the US, Canada, and the UK.

Using Yup.object().shape, we define our main validation schema which changes based on the value of the country field using Yup.string().when.

Conclusion
By leveraging Formik and Yup, you can create dynamic validation schemas for your forms, making form validation both maintainable and flexible. This approach ensures user input is validated accurately depending on their selections, providing a smoother user experience.