Delete unreferenced assets in Sanity

delete-unused-assets.ts

/*
This migration will delete all unused assets from the targeted Sanity dataset
*/
import { defineQuery } from 'groq'
import { defineMigration, delete_ } from 'sanity/migrate'

const unrefedAssets = defineQuery(`*[_type in ['sanity.imageAsset', 'sanity.fileAsset']] {
    _id,
    'refs': count(*[references(^._id)])
  }[refs == 0][$start..$end]._id`)

function createPager() {
  const size = 50
  const page = {
    start: 0,
    end: size - 1,
  }

  function increment() {
    page.start += size
    page.end += size
  }

  return {
    page,
    increment,
  }
}

export default defineMigration({
  title: 'Delete unused files',

  async *migrate(_, context) {
    const { page, increment } = createPager()

    while (true) {
      const results = await context.client.fetch(unrefedAssets, page)

      if (results.length == 0) {
        break
      }

      for (const id of results) {
        yield delete_(id)
      }

      increment()
    }
  },
})