@sanity/migrate/src/fetch-utils/fetchStream.ts

Tooling for running data migrations on Sanity.io projects

import {streamToAsyncIterator} from '../utils/streamToAsyncIterator.js'

export interface FetchOptions {
  init: RequestInit
  url: string | URL
}

interface ErrorResponse {
  error?:
    | string
    | {
        description?: string
        type?: string
      }
  message?: string
}

export class HTTPError extends Error {
  statusCode: number

  constructor(statusCode: number, message: string) {
    super(message)
    this.name = 'HTTPError'
    this.statusCode = statusCode
  }
}

export async function assert2xx(res: Response): Promise<void> {
  if (res.status < 200 || res.status > 299) {
    const jsonResponse = (await res.json().catch(() => null)) as ErrorResponse | null

    let message: string

    if (jsonResponse?.error) {
      if (typeof jsonResponse.error === 'object') {
        message = jsonResponse.error.description
          ? `${jsonResponse.error.type || res.status}: ${jsonResponse.error.description}`
          : `${jsonResponse.error.type || res.status}: ${jsonResponse.message || 'Unknown error'}`
      } else {
        message = `${jsonResponse.error}: ${jsonResponse.message || ''}`
      }
    } else {
      message = `HTTP Error ${res.status}: ${res.statusText}`
    }

    throw new HTTPError(res.status, message)
  }
}

export async function fetchStream({init, url}: FetchOptions) {
  const response = await fetch(url, init)
  await assert2xx(response)
  if (response.body === null) throw new Error('No response received')
  return response.body
}

export async function fetchAsyncIterator(options: FetchOptions) {
  return streamToAsyncIterator(await fetchStream(options))
}