@helia/car provides import and export methods to read/write Car files to Helia's blockstore.

See the Car interface for all available operations.

By default it supports dag-pb, dag-cbor, dag-json and raw CIDs, more esoteric DAG walkers can be passed as an init option.

Example: Exporting a DAG as a CAR file

import { createHelia } from 'helia'
import { unixfs } from '@helia/unixfs'
import { car } from '@helia/car'
import { CarWriter } from '@ipld/car'
import { Readable } from 'node:stream'
import nodeFs from 'node:fs'

const helia = createHelia({
  // ... helia config
})
const fs = unixfs(helia)

// add some UnixFS data
const cid = await fs.addBytes(fileData1)

// export it as a Car
const c = car(helia)
const { writer, out } = await CarWriter.create(cid)

// `out` needs to be directed somewhere, see the @ipld/car docs for more information
Readable.from(out).pipe(nodeFs.createWriteStream('example.car'))

// write the DAG behind `cid` into the writer
await c.export(cid, writer)
Copy

Example: Importing all blocks from a CAR file

import { createHelia } from 'helia'
import { unixfs } from '@helia/unixfs'
import { car } from '@helia/car'
import { CarReader } from '@ipld/car'
import { Readable } from 'node:stream'
import nodeFs from 'node:fs'

const helia = createHelia({
  // ... helia config
})

// import the car
const inStream = nodeFs.createReadStream('example.car')
const reader = await CarReader.fromIterable(inStream)

await c.import(reader)
Copy