@helia/car


> Import/export car files from Helia

About

@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

``typescript
import { createHelia } from 'helia'
import { car } from '@helia/car'
import { CID } from 'multiformats/cid'
import nodeFs from 'node:fs'

const helia = await createHelia()
const cid = CID.parse('QmFoo...')

const c = car(helia)
const out = nodeFs.createWriteStream('example.car')

for await (const buf of c.export(cid, {
signal: AbortSignal.timeout(5_000)
})) {
out.write(buf)
}

out.end()
`

Example - Exporting a part of a UnixFS DAG as a CAR file

Here the graph traversal will start at root and include the blocks for
root, /foo, /bar, and all the blocks that make up baz.txt.

If there are other files/directories in the UnixFS DAG under root, they
will not be included.

root will be the only entry in the CAR file roots.

`typescript
import { createHelia } from 'helia'
import { car, UnixFSPath } from '@helia/car'
import { CID } from 'multiformats/cid'
import nodeFs from 'node:fs'

const helia = await createHelia()
const root = CID.parse('QmFoo...')

const c = car(helia)
const out = nodeFs.createWriteStream('example.car')

for await (const buf of c.export(root, {
signal: AbortSignal.timeout(5_000),
traversal: new UnixFSPath('/foo/bar/baz.txt')
})) {
out.write(buf)
}

out.end()
`

Example - Including traversal path above the root in a CAR

The includeTraversalBlocks option will include the traversal blocks in the
CAR when they would otherwise be excluded (for example when the traversal
starts in a parent of the export root).

Here baz is the CID for baz.txt.

The CAR file will include the blocks for parent, /foo, /bar, and
/baz.txt.

baz will be the only entry in the CAR file roots.

`typescript
import { createHelia } from 'helia'
import { car, UnixFSPath } from '@helia/car'
import { CID } from 'multiformats/cid'
import nodeFs from 'node:fs'

const helia = await createHelia()
const parent = CID.parse('QmFoo...')
const baz = CID.parse('QmBar...')

const c = car(helia)
const out = nodeFs.createWriteStream('example.car')

for await (const buf of c.export(baz, {
signal: AbortSignal.timeout(5_000),
traversal: new UnixFSPath(parent, '/foo/bar/baz.txt'),
includeTraversalBlocks: true
})) {
out.write(buf)
}

out.end()
`

Example - Importing all blocks from a CAR file

`typescript
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 = await createHelia({
// ... helia config
})

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

const c = car(helia)
await c.import(reader, {
signal: AbortSignal.timeout(5_000)
})
`

Install

`console
$ npm i @helia/car
`

Browser
``

API Docs

-

License

Licensed under either of

- Apache 2.0, (LICENSE-APACHE / )
- MIT (LICENSE-MIT / )

Contribute

Contributions welcome! Please check out the issues.

Also see our contributing document for more information on how we work, and about contributing in general.

Please be aware that all interactions related to this repo are subject to the IPFS Code of Conduct.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.