@sanity/schema/src/legacy/preview/fallbackPrepare.ts

import {pick} from 'lodash'

import stringify from './JSONStringifyHuman'

const OPTIONS = {
  maxEntries: 2,
  maxDepth: 2,
  maxBreadth: 2,
  ignoreKeys: ['_id', '_type', '_key', '_ref'],
}

export function createFallbackPrepare(fieldNames: any) {
  return (value: any) => ({
    title: stringify(pick(value, fieldNames), OPTIONS),
  })
}