Understanding the undefined Issue in React Hook Form Submissions

Learn why React Hook Form returns `undefined` for certain form fields and how to fix it by properly implementing custom input components using `React.forwardRef`.
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This video is based on the question https://stackoverflow.com/q/70569541/ asked by the user 'Demian' ( https://stackoverflow.com/u/13286402/ ) and on the answer https://stackoverflow.com/a/70574136/ provided by the user 'Saeed Shamloo' ( https://stackoverflow.com/u/11977929/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Why Does React Hook Form Return Undefined on Submit?

When building forms in a Next.js project using TypeScript and React Hook Form, encountering undefined values for fields on form submission can be frustrating. If you find that only some inputs are passing values while others return undefined, you're not alone. This issue often arises from how custom input components are implemented in relation to React Hook Form's requirements. In this post, we will explore this common pitfall and how to resolve it.

The Problem

Consider this log output after submitting your form:

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

In this example, the fields for title, description, and name are returning undefined, while rating is receiving a proper value. Let's break down what's going on and how we can fix it.

The Interface

Your form interface is defined as follows:

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

You want users to enter values for name, title, description, and select a rating, but only the rating is working as expected. The next step is to examine how you're registering your inputs.

The Form Setup

Here's a snippet of your form setup:

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

Here, you have Input and Textarea components using the register method to bind the inputs to the form state. However, if the custom input components aren't properly set up, React Hook Form won't be able to capture their values when the user submits the form.

The Solution: Implementing React.forwardRef

To fix the issue, you need to ensure your custom input components are correctly set up to work with React Hook Form. The solution is to use React.forwardRef in your Input component, as this allows React Hook Form to access the input's ref and manage its state appropriately.

Step-by-Step Implementation

Define the Input Component: Modify your Input component to use React.forwardRef. Here's an updated example:

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

Ensure Props are Passed: This changes how the input component receives and handles props. Ensure that all necessary props, including any others like className or styles, are appropriately passed to the native input element.

Why This Works

Using React.forwardRef allows React Hook Form to directly manage the input's focus and state, ensuring that the values are captured correctly when the form submits. This is crucial because React Hook Form relies on refs to gather data from input fields effectively.

Conclusion

If you've been struggling with undefined values in form submissions using React Hook Form, consider revising your custom input components to use React.forwardRef. This small change can make a significant difference in obtaining accurate form data. By following the outlined steps, you should see all your input values being returned as expected in the console log.

If you have any questions or need further clarification about using React Hook Form with custom components, feel free to ask in the comments below!

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