Access current document values in custom Sanity input component

Yes! You can absolutely access the current document's properties in your custom input component without making an API call. The solution is to use the useFormValue hook from Sanity.

Here's how to update your AsyncListInput component:

import { useFormValue } from 'sanity'

const AsyncListInput = (props: any) => {
    const { schemaType, renderDefault } = props

    // Access the entire document
    const document = useFormValue([])
    
    // Or access a specific field directly
    const dossierTypeId = useFormValue(['dossierTypeId'])

    // get values from API using dossierTypeId
    const values = /* your API call using dossierTypeId */

    return renderDefault({
        ...props,
        schemaType: { ...schemaType, options: { list: values } },
    })
}

The useFormValue hook takes an array path to the field you want to access:

• useFormValue([]) - returns the entire document
• useFormValue(['dossierTypeId']) - returns just the dossierTypeId field
• useFormValue(['nested', 'field', 'path']) - for deeply nested fields

This is the modern, recommended approach in Sanity Studio v3. In v2, you would have used the withDocument HOC, but that's been replaced with this hook-based approach.

Important note: The component will re-render whenever the field you're watching changes. If you're watching the entire document with useFormValue([]), it will re-render on any document change. For better performance, access only the specific field(s) you need.