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Using R2 in a Worker

A demo of how to use R2 in a Worker.

Below is an example Worker that exposes an R2 bucket to the Internet and demonstrates its functionality for storing and retrieving objects.

interface Env {
  MY_BUCKET: R2Bucket
}



function parseRange(encoded: string | null): undefined | { offset: number, length: number } {
  if (encoded === null) {
    return
  }


  const parts = encoded.split("bytes=")[1]?.split("-") ?? []
  if (parts.length !== 2) {
    throw new Error('Not supported to skip specifying the beginning/ending byte at this time')
  }


  return {
    offset: Number(parts[0]),
    end:    Number(parts[1]),
    length: Number(parts[1]) + 1 - Number(parts[0]),
  }

}



function objectNotFound(objectName: string): Response {
  return new Response(`<html><body>R2 object "<b>${objectName}</b>" not found</body></html>`, {
    status: 404,
    headers: {
      'content-type': 'text/html; charset=UTF-8'
    }
  })

}



export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const url = new URL(request.url)
    const objectName = url.pathname.slice(1)


    console.log(`${request.method} object ${objectName}: ${request.url}`)


    if (request.method === 'GET' || request.method === 'HEAD') {
      if (objectName === '') {
        if (request.method == 'HEAD') {
          return new Response(undefined, { status: 400 })
        }


        const options: R2ListOptions = {
          prefix: url.searchParams.get('prefix') ?? undefined,
          delimiter: url.searchParams.get('delimiter') ?? undefined,
          cursor: url.searchParams.get('cursor') ?? undefined,
          include: ['customMetadata', 'httpMetadata'],
        }
        console.log(JSON.stringify(options))


        const listing = await env.MY_BUCKET.list(options)
        return new Response(JSON.stringify(listing), {headers: {
          'content-type': 'application/json; charset=UTF-8',
        }})
      }


      if (request.method === 'GET') {
        const range = parseRange(request.headers.get('range'))
        const object = await env.MY_BUCKET.get(objectName, {
          range,
          onlyIf: request.headers,
        })


        if (object === null) {
          return objectNotFound(objectName)
        }


        const headers = new Headers()
        object.writeHttpMetadata(headers)
        headers.set('etag', object.httpEtag)
        if (range) {
          headers.set("content-range", `bytes ${range.offset}-${range.end}/${object.size}`)
        }
        const status = object.body ? (range ? 206 : 200) : 304
        return new Response(object.body, {
          headers,
          status
        })
      }


      const object = await env.MY_BUCKET.head(objectName)


      if (object === null) {
        return objectNotFound(objectName)
      }


      const headers = new Headers()
      object.writeHttpMetadata(headers)
      headers.set('etag', object.httpEtag)
      return new Response(null, {
        headers,
      })
    }
    if (request.method === 'PUT' || request.method == 'POST') {
      const object = await env.MY_BUCKET.put(objectName, request.body, {
        httpMetadata: request.headers,
      })
      return new Response(null, {
        headers: {
          'etag': object.httpEtag,
        }
      })
    }
    if (request.method === 'DELETE') {
      await env.MY_BUCKET.delete(url.pathname.slice(1))
      return new Response()
    }


    return new Response(`Unsupported method`, {
      status: 400
    })
  }

}