Accessing document data in custom input components after v2 to v3 migration

import { useFormValue } from 'sanity'

const MyCustomInput = (props) => {
  const document = useFormValue([]) // Empty array returns entire document
  
  // Now you can access any field from the document
  console.log(document._id, document.title, etc.)
  
  return (
    // your component JSX
  )
}

// Access a specific field
const title = useFormValue(['title'])

// Access nested fields
const authorName = useFormValue(['author', 'name'])

// Access document ID
const docId = useFormValue(['_id'])

// Access parent field (if your input is nested)
const { path } = props
const parentPath = path.slice(0, -1)
const parentValue = useFormValue(parentPath)

import { useFormValue } from 'sanity'

const DynamicListInput = (props) => {
  const categoryId = useFormValue(['category']) // Access sibling field
  const [options, setOptions] = useState([])
  
  useEffect(() => {
    if (categoryId) {
      // Fetch options based on category
      fetchOptions(categoryId).then(setOptions)
    }
  }, [categoryId])
  
  return props.renderDefault({
    ...props,
    schemaType: { 
      ...props.schemaType, 
      options: { list: options } 
    }
  })
}