React: Dynamic Dropdowns with Formik - How to Handle Nested Field Arrays?
I've tried everything I can think of but I've been banging my head against this for hours. I'm relatively new to this, so bear with me. I'm working on a personal project and I'm working on a form using Formik and I've run into an scenario with dynamically generating dropdowns based on user selections... The form structure involves nested field arrays, and I'm trying to create a dependent dropdown where the options for the second dropdown are determined by the selection in the first. I've set up my state and handlers correctly, but I'm working with issues with updating the options in the second dropdown when the first dropdown changes. Here's the relevant part of my code: ```javascript import React from 'react'; import { Formik, Field, Form, FieldArray } from 'formik'; const options = { category1: ['Option 1', 'Option 2', 'Option 3'], category2: ['Option A', 'Option B'] }; const MyForm = () => { return ( <Formik initialValues={{ items: [{ category: '', subCategory: '' }] }} onSubmit={values => console.log(values)} > {({ values, setFieldValue }) => ( <Form> <FieldArray name='items'> {({ push, remove }) => ( <div> {values.items.map((item, index) => ( <div key={index}> <Field as='select' name={`items.${index}.category`} onChange={e => { const selectedCategory = e.target.value; setFieldValue(`items.${index}.category`, selectedCategory); setFieldValue(`items.${index}.subCategory`, ''); // reset subCategory }}> <option value=''>Select Category</option> {Object.keys(options).map(option => ( <option key={option} value={option}>{option}</option> ))} </Field> <Field as='select' name={`items.${index}.subCategory`}> <option value=''>Select Subcategory</option> {options[item.category]?.map(sub => ( <option key={sub} value={sub}>{sub}</option> ))} </Field> <button type='button' onClick={() => remove(index)}>Remove</button> </div> ))} <button type='button' onClick={() => push({ category: '', subCategory: '' })}>Add Item</button> </div> )} </FieldArray> <button type='submit'>Submit</button> </Form> )} </Formik> ); }; export default MyForm; ``` The question I'm working with is that when I select a category in the first dropdown, the second dropdown does not update its options correctly. I've checked the console for errors, but there’s nothing. The `options[item.category]` is returning `undefined`, even though I can see the category value in the form state. I'm using Formik version 2.2.6 and React 17.0.2. Any thoughts on what might be going wrong or how I can debug this? Any best practices for handling such dynamic dropdowns effectively would be really helpful too. Thanks! My development environment is Windows. What's the best practice here? For context: I'm using Javascript on macOS. Any help would be greatly appreciated! I'm coming from a different tech stack and learning Javascript. Has anyone else encountered this? Could someone point me to the right documentation?