Using the CLI for mutations in Sanity and resolving a permissions issue.

import sanityClient from 'part:@sanity/base/client'
const client = sanityClient.withConfig({
  apiVersion: '2021-11-01',
})


const fetchDocuments = () =>
  client.fetch(`*[_type == 'deal']{_id, title, publishedDate}[0..1]`)

const buildPatches = docs => {
  return docs.map(doc => {
    console.log(doc.title);
    const pubDate = new Date(doc.publishedDate);
    pubDate.setDate( pubDate.getDate() - 60 );
    return {
      id: doc._id,
      patch: {
        set: {
          publishedDate: pubDate
        }
      }
    }
  })
}

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

const commitTransaction = tx => tx.commit()

const migrate = async () => {
  const documents = await fetchDocuments()
  const patches = buildPatches(documents)
  console.log(
    `Migrating batch:\n %s`,
    patches.map(patch => `${patch.id} => ${JSON.stringify(patch.patch)}`).join('\n')
  )
  const transaction = createTransaction(patches)
  return await commitTransaction(transaction)
}

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