📁 __File — File Validation in nestvalidate()

Applies to nestvalidate() only. validate() does not recurse into nested objects — pass a raw File directly with no wrapper needed.

File objects are JavaScript objects. Without a wrapper, nestvalidate would detect a File as a nested structure and try to recurse into its DOM properties. __File() wraps the file and tells drea: treat this as a single value, not a nested object.

import { __File, CustomClassicModel } from 'drea'

const schema = {
  avatar: [
    {
      rule: (v: File | null) => v instanceof File || v === null,
      errorMsg: 'Please select an image'
    },
    {
      rule: (v: File | null) => v === null || ['image/jpeg','image/png','image/webp'].includes(v.type),
      errorMsg: 'Only JPG, PNG, or WebP accepted'
    },
    {
      rule: (v: File | null) => v === null || v.size <= 6 * 1024 * 1024,
      errorMsg: 'Max file size is 6 MB'
    }
  ]
}

const model = new CustomClassicModel(schema)

// ✅ Wrap with __File before passing to nestvalidate
model.nestvalidate({ avatar: __File(fileFromInput) })

// ✅ null (no file selected) — pass directly, no __File needed
model.nestvalidate({ avatar: null })

File constructor reminder:

// new File(fileBits, fileName, options?)
const file = new File([new ArrayBuffer(2 * 1024 * 1024)], 'photo.jpg', { type: 'image/jpeg' })

Guard: AssertDreaFile(v, 'v') runs inside __File — rejects anything that is not a File instance.

__File('path/to/file.jpg' as any)
// throws ArgumentTypeError: "Expected File instance for 'v', got string"

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