zodにも限界がある例

toRawDeep.ts

import { toRaw } from 'vue'
import { z } from 'zod'

/**
 * ```typescript
 * import { ref } from 'vue'
 * const x = ref({ a: { b: 42 } })
 * // const y = structureClone(toRaw(x.value)) // 深いProxy（x.value.a.b）を除去できずに例外が出る
 * const y = structureClone(toRawDeep(x.value)) // OK
 * ```
 */
export const toRawDeep = <T>(ref: T, schema: z.ZodType<T>): T => {
  const raw = toRaw(ref)

  if (Array.isArray(raw)) {
    // return raw.map(toRawDeep) as T // `as`を使いたくないのでzodを使おうとするが…
    return schema.parse(
      raw.map((x) => toRawDeep(x, schema.element())) // schemaがZodArrayであることを正当化できない
    )
  }

  if (raw === null) {
    return null as T
  }

  if (raw === undefined) {
    return undefined as T
  }

  if (typeof raw === 'object') {
    const entries = Object.entries(raw).map(([key, raw]) => [
      key,
      toRawDeep(raw),
    ])
    return Object.fromEntries(entries)
  }

  return raw
}