How to import documents, and add them as a new item in an array of references with Sanity.io

import.js

/**
 * import.js
 *
 * Install dependencies:
 * yarn add p-queue nanoid
 * or
 * npm i p-queue nanoid && sanity install
 *
 * Run this script with:
 * sanity exec --with-user-token import.js
 */

import client from 'part:@sanity/base/client'
import PQueue from 'p-queue'
import {customAlphabet as generateId, nanoid} from 'nanoid'
import signees from './signees-file.json'

const CATEGORY_ID = 'the-_id-to-your-category-document'

/**
 * We use PQueue do prevent hitting the rate limit.
 * https://www.sanity.io/docs/importing-data
 */
const queue = new PQueue({
  concurrency: 1,
  interval: 1000 / 25
})

/**
 * Loop through the documents, add the signee document,
 * and append it to the category document’s references array
 * https://www.sanity.io/docs/js-client
 */
signees.forEach(async signee => {
  let _id = generateId('1234567890abcdefghijklmnopqrstuvwz', 20)()

  // Add the new document
  await queue.add(() => client.create({
    _id,
    _type: 'signee',
    ...signee
  }).then(doc => console.log(`created ${doc._id}`)))

  // insert a new reference object at the end of the signees array
  await queue.add(() => client.patch(CATEGORY_ID).insert('after', 'signees[-1]', [
    { _key: nanoid(), _type: 'reference', _ref: _id }
  ]).commit().then(result => console.log(`updated ${result._id}`)))
})