Sorting content by date in Sanity with a custom script

sanity exec path/to/script.js --with-user-token

import sanityClient from 'part:@sanity/base/client'

const client = sanityClient.withConfig({ apiVersion: '2022-05-06' })

const fetchDocuments = () =>
  client.fetch(`*[DATETIME_FIELD != null && NEW_DATE_FIELD == null][0...100] {_id, _rev, DATETIME_FIELD, NEW_DATE_FIELD}`)

const buildPatches = docs =>
  docs.map(doc => ({
      id: doc._id,
      patch: {
        set: {NEW_DATE_FIELD: doc.DATETIME_FIELD.slice(0, 10)},
        // this will cause the migration to fail if any of the documents has been
        // modified since it was fetched.
        ifRevisionID: doc._rev
      }
    }))

const createTransaction = patches =>
  patches.reduce((tx, patch) => tx.patch(patch.id, patch.patch), client.transaction())

const commitTransaction = tx => tx.commit()

const migrateNextBatch = async () => {
  const documents = await fetchDocuments()
  const patches = buildPatches(documents)
  if (patches.length === 0) {
    console.log('No more documents to migrate!')
    return null
  }
  console.log(
    `Migrating batch:\n %s`,
    patches.map(patch => `${patch.id} => ${JSON.stringify(patch.patch)}`).join('\n')
  )
  const transaction = createTransaction(patches)
  await commitTransaction(transaction)
  return migrateNextBatch()
}

migrateNextBatch().catch(err => {
  console.error(err)
  process.exit(1)
})