How to convert piece CID string to hex bytes

[longfeiWan9]

When submitting storage deal proposal via client contract, we normally need to pass pieceCID in bytes format. But when we prepare data using tools like lighthouse.storage or generate-car, we normally receive pieceCID in string format.

For instance, pieceCID = "baga6ea4seaqkp2pjlh6avlvee6ib2maanav5sc35l5glf3zm6rd6hmfgcx5xeji". How to convert it to bytes format.

[longfeiWan9]

First, you should have the cids library and use it in your JS file const CID = require('cids').

Then you can convert it like the following code.

pieceCID = 'baga6ea4seaqkp2pjlh6avlvee6ib2maanav5sc35l5glf3zm6rd6hmfgcx5xeji'
const cidHexRaw = new CID(pieceCID).toString('base16').substring(1)
const cidHex = "0x00" + cidHexRaw

cidHex is the CID in raw hex format to use when you submit storage deal via client contract.