What datatype should I use for an IPFS address hash?

Question

Here is an IPFS hash: QmTfCejgo2wTwqnDJs8Lu1pCNeCrCDuE4GAwkna93zdd7d. According to IPFS docs, they are base58 encoded, and I assume the Qm is metadata (because they all share this).

What is the most effective datatype to store one of these?

Edit: they do not all start with Qm

Answer 1

bytes because they are more than 32 bytes. An IPFS hash:

itself specifies the hash function and length of the hash in the first two bytes of the multihash. In the examples above the first two bytes in hex is 1220, where 12 denotes that this is the SHA256 hash function and 20 is the length of the hash in bytes - 32 bytes.

Source

Although SHA2-256 is 32 bytes and currently the most common IPFS hash, other content could use a hash function that is larger than 32 bytes.

Answer 2

You can store any IPFS hash in bytes32.
You will need cids npm package.

Example:

export function IpfsHashToBytes32(hash: string)
{
    return new CID(hash).toV0().multihash.subarray(2)
}

export function bytes32ToIpfsHash(bytes: Uint8Array)
{
    return new CID(new Uint8Array([18, 32, ...bytes])).toString()
}

First two bytes are hash version prefixes, so you don't need them.