Simple migration script that can be run with `sanity exec` in a Sanity Studio

migration.js

// migration.js
/**
 * Run:
 * sanity exec --with-user-token migration.js
 *
 */
import sanityClient from 'part:@sanity/base/client'
const client = sanityClient.withConfig({ apiVersion: '2021-11-10' })
// Patch 1000 at a time
const query = `*[_type == "stream"][0...999]{title, publishedDate, _id, _rev}`

async function migrate() {

  const docs = await client.fetch(query)

  const patches = docs.map((doc) => ({
    id: doc._id,
    patch: {
      set: {
        test: true
      },
    },
    ifRevisionID: doc._rev, // prevent race conditions
  }))

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

  const result = await transactions.commit()
  console.log('Done!')
  console.log(JSON.stringify(result, null, 2))

}
migrate()